Journal Cover
Acta Astronautica
Journal Prestige (SJR): 0.758
Citation Impact (citeScore): 2
Number of Followers: 420  
 
  Hybrid Journal Hybrid journal (It can contain Open Access articles)
ISSN (Print) 0094-5765
Published by Elsevier Homepage  [3160 journals]
  • The role of body fluid shifts on hindlimb bone loss in tail suspended rats
           using a novel body fluid alteration device
    • Abstract: Publication date: June 2019Source: Acta Astronautica, Volume 159Author(s): Shouhui Wang, Xiao Yang, Min Wang, Yunfei Huang, Dieter Blottner, Lian-Wen Sun, Yu-Bo Fan In space, the mechanical loading of the weight-bearing bone decreases and the body fluid shifts cephalad. However, the correlative researches are rarely reported on how the body fluid shift affects the bone, especially how it affects the weight-bearing bone in space or in bed rest on the ground. In our study, a novel model was designed to investigate the effect of body fluid shifts on the bone loss of the hindlimbs in the tail-suspended rats. The model can keep the rat hindlimb unloaded, and change the distribution of the body fluid by altering rats’ body position. The study was conducted for 21 days. Thirty-six female Sprague-Dawley rats were randomly divided into four groups (n = 9, each): control group (CON), head-down tail-suspension group (HDT), head-horizontal tail-suspension group (HHT), head-up tail-suspension group (HUT). The results indicated that body fluid shifting towards the tail end may inhibit the bone loss of the rat hindlimbs, that means the absence of cephalad body fluid shifting resulted in the positive effect on the bone microstructure parameters and the mechanical properties. The results suggested that the backflow of the body fluid in rat hindlimbs was able to alleviate the disuse osteoporosis in a certain extent.
       
  • ZERODUR® based optical systems for quantum gas experiments
           in space
    • Abstract: Publication date: Available online 22 March 2019Source: Acta AstronauticaAuthor(s): Moritz Mihm, Jean Pierre Marburger, André Wenzlawski, Ortwin Hellmig, Oliver Anton, Klaus Döringshoff, Markus Krutzik, Achim Peters, Patrick Windpassinger, the MAIUS Team Numerous quantum technologies make use of a microgravity environment e.g. in space. Operating in this extreme environment makes high demands on the experiment and especially the laser system regarding miniaturization and power consumption as well as mechanical and thermal stability. In our systems, optical modules consisting of ZERODUR® based optical benches with free-space optics are combined with fiber components. Suitability of the technology has been demonstrated in the successful sounding rocket missions FOKUS, KALEXUS and MAIUS-1. Here, we report on our toolkit for stable optical benches including mounts, fixed and adjustable mirrors as well as polarization maintaining fiber collimators and couplers made from ZERODUR®. As an example, we present the optical modules for the scientific rocket payload of MAIUS-2, a quantum gas experiment performing dual-species atom interferometry with Bose-Einstein condensates. The modules are used on the one hand to stabilize the laser frequencies and on the other hand to distribute, overlap and switch the laser beams. This includes the overlap and joint fiber coupling of beams at 767 nm and 780 nm in the same polarization state to cool and manipulate atoms of both species simultaneously. Future projects include the development of a platform for experiments with cold atoms onboard the International Space Station. The laser system again involves ZERODUR® based optical benches in conjunction with fiber optical components. The experiment is planned as multi-user facility and currently in the design phase. The next step is to build the training, test and flight hardware.
       
  • Numerical analysis of laser-pulse transient ignition of oxygen/methane
           mixtures in rocket-like combustion chamber
    • Abstract: Publication date: Available online 21 March 2019Source: Acta AstronauticaAuthor(s): G. Gargiulo, P.P. Ciottoli, E. Martelli, R. Malpica Galassi, M. Valorani This paper describes a numerical study of the laser-pulse ignition sequence occurring in the combustion chamber of the M3 facility at DLR-Lampoldshausen. Our methodological approach relies on a variable fidelity modeling of the main phenomena of interest. In-house tools are fed with spatially homogeneous, isochoric, forced ignition problems, to derive a simplified methane/oxygen kinetic mechanism. The kernel formation after the laser pulse energy deposition is firstly studied in a one-dimensional framework, so as to test the simplified kinetic mechanism ability to reproduce the ignition behavior. The kernel initiation is also simulated in a two-dimensional mixing layer, to assess the ability of the simplified mechanism to accurately describe both the kernel initiation and its spatial propagation. Both the one- and two-dimensional simulations are carried out by means of a wavelet-based CFD library. Next, a lumped analysis of the events connected with the ignition sequence is carried out by adopting a well-stirred reactor model for the M3 chamber. The numerical results are compared to experiments carried out by DLR-Lampoldshausen, and the discrepancies are discussed. Finally, the whole M3 geometry and ignition sequence are simulated by means of an Unsteady Reynolds-averaged Navier-Stokes (URANS) model under the axi-symmetric flow approximation. The URANS results are compared with the experimental data, showing that URANS axi-symmetric calculation are able to provide a rather accurate picture of the ignition transients. Nevertheless, some issues on the quantitative accuracy of the URANS predictions are found and discussed in detail.
       
  • High-fidelity contingency trajectory design and analysis for NASA's
           near-earth asteroid (NEA) Scout solar sail Mission
    • Abstract: Publication date: Available online 21 March 2019Source: Acta AstronauticaAuthor(s): James Pezent, Rohan Sood, Andrew Heaton Exploratory missions to investigate accessible Near Earth Asteroids (NEAs) can benefit from leveraging dynamics associated with a solar sail-based spacecraft. As a part of this effort, NEA Scout is a solar sail mission designed to propel a 6U CubeSat by harnessing solar radiation pressure from the Sun. The spacecraft will be launched as a secondary payload on NASA's Space Launch System (SLS) Exploration Mission One (EM-1). As the launch of EM-1 has recently been rescheduled for December 2019, alternative target NEAs are identified. Additionally, solar sail-based trajectories for the NEA Scout mission also need to be reevaluated. In this study, high-fidelity trajectories for the NEA Scout mission are investigated for varying launch dates under the assumption of the failure of a critical propulsive maneuver. Furthermore, feasible trajectory solutions are presented for multiple candidate asteroids.
       
  • Flame propagation in weightlessness above the burning surface of material
    • Abstract: Publication date: Available online 21 March 2019Source: Acta AstronauticaAuthor(s): Veronika V. Tyurenkova, Lyuben I. Stamov Numerical simulations of three-dimensional flow of a gas mixture with chemical reactions over a flat thermally destructing material surface are presented. To create an effective numerical model, two ways of determining the heat removal are considered, and a comparison with the analytical solution obtained within the frame of the boundary layer approximation is represented. As an example, the numerical simulations of three-dimensional flow in combustion chamber of hybrid rocket are performed. The temperature maps and molar fraction of fuel within the chamber for different times are shown.
       
  • Non-stationary process of accelerating the measuring probe in the
           laboratory ballistic module
    • Abstract: Publication date: Available online 21 March 2019Source: Acta AstronauticaAuthor(s): M. Yu Sotskiy, V.A. Veldanov, V.V. Selivanov A variant of the technology of dynamic contact sensing of rheological media, including a wired connection for connecting the measuring probe with the recorder, is presented. The results of a series of laboratory experiments with high-speed imaging of the process from the beginning of the movement of the measuring probe and the wire of electrical communication in the starting device to the end of the movement of the probe in the target medium are shown. The process of the impact of the detonation products of the working gas on the probe and on the elements of the measuring assembly is analyzed. Based on the analysis of the evolution of the shape of the electric wire, conditions were determined that ensure the reliability of recording the motion parameters of the measuring probe on the flight path and in the target.
       
  • From multiscale modeling to design of synchronization mechanisms in mesh
           antennas
    • Abstract: Publication date: Available online 21 March 2019Source: Acta AstronauticaAuthor(s): Kangjia Fu, Zhihua Zhao, Gexue Ren, Yong Xiao, Tao Feng, Jungang Yang, Paolo Gasbarri Flexible multibody simulation is supposed to be a promising method for studying the deployment dynamics of large mesh antennas and assisting the design of the related crucial mechanisms. However, fulfilling a full-scale deployment simulation of a mesh antenna is so challenging that it can be rarely found in the literature. In our opinion, the bottleneck of modeling some mesh antennas is dealing with the multiscale physics mainly sourced from the cable-pulley systems that are frequently used to transfer forces for long distance range. A traditional model of a cable-pulley is based on contact method, which involves fine cable mesh, a large amount of contact detection, and small time step for numerical integration, resulting in low calculation efficiency. To cope with this difficulty, we proposed a novel and efficient multiscale method to handle the cable-pulley systems. The basic idea is avoiding the contact detection by separating a cable into two segments: non-contact and contact segments, according to which part of the cable is in contact with the pulley. The non-contact segment is meshed with variable-length elements based on the arbitrary Lagrangian–Eulerian (ALE) formulation. The contact segment is considered an invisible segment to constrain the variable-length cable element on the pulley; its border is dynamically located by the relative configuration between the pulley and the cable. The accuracy and efficiency of the proposed method were confirmed by a numerical example. Then, it was used to evaluate, compare and design the synchronization mechanism in a kind of mesh antenna. The obtained results can directly guide the actual design of mesh antennas, and the proposed multiscale method can be applied to simulating other similar mechanical systems.
       
  • Hardware and GNC solutions for controlled spacecraft re-entry using
           aerodynamic drag
    • Abstract: Publication date: Available online 21 March 2019Source: Acta AstronauticaAuthor(s): Sanny R. Omar, Riccardo Bevilacqua Traditionally, controlled spacecraft re-entries have been conducted using propulsive de-orbit burns which are risky, expensive, and may not be possible for all vehicles. Recently, the miniaturization of technology has ushered in a new class of small satellites (such as CubeSats) that are too small to host thrusters but may require a controlled de-orbit if they contain materials capable of surviving re-entry. For all space vehicles requiring a controlled re-entry, the ability to harness the naturally occurring aerodynamic drag force for orbit control provides a cheaper and more reliable alternative to chemical propulsion.This paper discusses a comprehensive method for drag-controlled re-entry that is applicable to any vehicle capable of modulating its ballistic coefficient. First, a novel guidance generation algorithm efficient enough to run onboard a CubeSat outputs a desired ballistic coefficient profile and corresponding numerically propagated trajectory that if followed, will lead the spacecraft to a desired de-orbit location. This guidance generation algorithm is based on an analytical solution that provides convergence guarantees, ensures rapid performance, and facilitates a controllability analysis. Next, the guidance tracking algorithm utilizes an extended Kalman filter and GPS measurements to estimate the position and velocity of the satellite relative to the guidance. A full state feedback linear-quadratic-regulator (LQR) control strategy is then used to drive the relative position and velocity to zero using solely aerodynamic drag. This paper also discusses a novel retractable drag de-orbit device (D3) that can be attached to existing CubeSat structures and can easily be scaled up for larger satellites. The D3 provides passive three-axis attitude stabilization using aerodynamic and gravity gradient forces and can be repeatedly modulated to perform aerodynamically-based orbital maneuvering and controlled re-entry. The design of the planned 2U CubeSat to test the D3 and control algorithms in flight is also discussed.The re-entry point targeting algorithms were validated through extensive Monte Carlo simulations which included realistic GPS measurement errors and drag force uncertainties. The algorithms were able to guide the satellite to a desired de-orbit location with an average error below 25 km and in all cases, the targeting error was low enough for debris mitigation purposes. The accuracy and reliability of these algorithms coupled with the D3 device that has successfully undergone thermal vacuum, vibration, and fatigue testing provide a cheap, reliable, and comprehensive attitude, orbit, and de-orbit control solution that can be used on large and small space vehicles, possibly replacing conventional propulsion and attitude control systems and making space more accessible to everyone.
       
  • Integration of star pixel coordinates and their time differential
           measurement in satellite stellar refraction navigation
    • Abstract: Publication date: Available online 21 March 2019Source: Acta AstronauticaAuthor(s): Xiaolin Ning, Xiaohan Sun, Wen Chao The refraction apparent height, the stellar refraction angle, and the star pixel coordinates are three kinds of typical celestial measurements used in the stellar refraction navigation system. All three measurements are functions of the current position of the satellite. A new kind of time differential measurement is proposed in this paper, inspired by time differential technology, which is a function of both the position and velocity of satellites. In this paper, the time differential star pixel coordinate measurement is taken as an example to show the acquisition of measurement and the establishment of the measurement model in detail. Simulations show that better navigation performance can be achieved by integrating the typical celestial measurements and their time differential measurement for a low-Earth orbit satellite, regardless of which celestial measurement is used.
       
  • Finite-time stability of an underactuated tethered satellite system
    • Abstract: Publication date: Available online 20 March 2019Source: Acta AstronauticaAuthor(s): Chen Wang, Fan Zhang The tethered satellite system has been extensively studied due to its widespread applications for space missions. However, the tether's oscillation draws back the performance of the system, and furthermore this oscillation is governed by an uncontrollable state. In this paper, an adaptive hierarchical second-order sliding mode control scheme is proposed to suppress the oscillation of space tether, and disturbance as well. Based on the dynamics equations, system energy of the tethered satellite system is further studied. A reference sliding variable is addressed to strengthen the coupling between the controllable and uncontrollable state. The proposed second-order sliding control scheme can suppress the oscillation and disturbance effectively, and meanwhile can weaken the control chattering. The closed-loop stability with the addressed references sliding variable is strictly verified via Lyapunov function. Finally, the proposed controller is verified by numerical simulations of both deployment and retrieval. With the comparison of other control scheme shows that the sub-satellite can be deployed and retrieved quickly and stably under the proposed scheme. Furthermore, the simulations in presence of disturbance prove the robustness of the proposed controller.
       
  • Pillow talk—Curating delight for astronauts
    • Abstract: Publication date: Available online 20 March 2019Source: Acta AstronauticaAuthor(s): Tibor S. Balint, Chang Hee Lee In a not so distant future, human explorers will venture farther away from the Earth. To enable long duration space missions, we need to advance space habitat designs beyond today's technological solutions, focusing on the astronauts' basic physiological and psychological needs. In addition, we must design for the crew's wellbeing and comfort, while reducing stress and enhancing their privacy. This goal can be addressed by designers and artists, who are skilled to lead facilitated conversations, create mockups, prototypes, and boundary objects, with curated affordances that respond to astronaut needs. One of the simplest examples of an artifact that provides comfort to a user is a pillow. At first glance, the meaning of a pillow in zero gravity is not obvious. Yet, exploring it deeper, the space environment also opens possibilities for experimentations and conversations around a reimagined space pillow artifact, with broadened affordances, while also supporting vitruvian delight. For example, stimulating the limbic brain through the sensory system (including touch, olfaction, hearing, vision, and taste) reduces stress. In this paper we discuss our design process, which includes our rationale to select this unlikely artifact as a representative boundary object. We discuss the ideation process on form and function, from head support to attachments to the habitat's wall. We explore the materiality and aesthetics of the outer skin layer, and curated interactivity options through soundscape, light, and smell. Our first-generation artifact acts as a proof of concept with a subset of all possible affordances. It is a forward looking search, in line with second-order cybernetics, where the outcomes inform us towards the development of subsequent space pillow versions. We use this boundary object to initiate a conversation about facilitated interactions between objects inside space habitats and the crew, and exemplify how artistic and designerly processes can contribute to space exploration. We also discuss the need to address higher-level astronaut needs on long duration spaceflight, through an artifact that provides an emotional connection and bridge between the space travelers and their terrestrial home. During this process we also expect to broaden our concepts to other artifacts inside space habitats with user interactions and curated autonomy in support of discovery, learning, relaxation, comfort and wellbeing. By choosing a pillow as a focal point of this project, we are hoping to engage artists, designers, and space architects to reframe the discourse around space exploration, and to broaden today's technology-driven human space exploration paradigm.
       
  • Bionics design and dynamics analysis of space webs based on spider
           predation
    • Abstract: Publication date: Available online 20 March 2019Source: Acta AstronauticaAuthor(s): Boting Xu, Yueneng Yang, Ye Yan, Bin Zhang A new bionic space debris removal device, inspired by the spider predation, is designed in this paper, which consists of flexible webs, central hub, traction mass and rotating mechanism. Firstly, the concept of bionic space debris removal and corresponding system design are described in detail. Secondly, the dynamic models of spin deployment and collision are derived and foumulated respectively. Thirdly, a finite element analysis is presented to simulate the dynamic characteristics of the spinning webs deployment process. In addition, a finite element model of the webs is developed for structural modal analysis. Finally, a number of collision simulation analysis are carried out using finite element method and propagation of small disturbances along the tether are demonstrated via numerical simulations. The simulation results effectively reflect that the motion characteristics of the large deformation and large displacement in the process of capturing the target. Furthermore, it show that the proposed novel bionic flexible web can meet design requirements for a space debris removal system.
       
  • Altitude estimation for a celestial navigation system based on infrared
           Earth measurement
    • Abstract: Publication date: Available online 20 March 2019Source: Acta AstronauticaAuthor(s): Bin Gou, Yong-mei Cheng, Anton H.J. de Ruiter The navigation stars captured by the star sensor are far away from the spacecraft; this creates a strong similarity among star images at similar locations, attitudes but different altitudes, and renders the celestial navigation system (CNS) unable to measure the spacecraft altitude. This paper proposes a spacecraft altitude estimation method for the CNS based on infrared Earth measurement. An infrared Earth sensor first determines the Earth observation vector between the spacecraft and the Earth center relative to the inertial frame. The geographic distance between the Earth center and the Earth edge in the infrared Earth image is then calculated. Finally, the spacecraft altitude is estimated based on the triangle relationship between the spacecraft location, the Earth center, and the infrared Earth image's Earth edge relative to the inertial frame. Simulation results illustrate that the proposed method is extremely effective in high-accuracy altitude estimation. Compared to high-altitude missions with different altitudes, the altitude estimation accuracy is limited into 0.4% of the true altitude.
       
  • Experimental verification and comparison of different tailoring models for
           spacecraft electronics thermal cycling tests
    • Abstract: Publication date: Available online 17 March 2019Source: Acta AstronauticaAuthor(s): Xin-Yan Ji, Guo-Qing Liu, Jing Wang, Xiao-Ning Yang, Shu-Hong Xiang, Yan-Qiang Bi Thermal cycling tests (TCT) have been widely used for performance demonstration and reliability validation of the spacecraft electronics. The integrated tailoring model can provide customized testing conditions of TCT for different spacecraft electronics, which is different with the traditional unified tailoring model in MIL-STD-1540. Considering the influence of welding material, defect degrees and test levels, experimental verification had been done on solder samples. The evaluation indicators including test cost, simulation bias and simulation accuracy have been defined and compared between two different tailoring methods. The results show that for Sn/Pb solder samples, the testing effects of the two tailoring methods are the same. But for other materials solder samples, the integrated method can be used to achieve better environmental stress screening with lower cost than the traditional method. Such as the SAC solder, the simulation accuracy is increased by 0–10%, and the testing cost is decreased by 0–7%.
       
  • Propagation of strong shock waves in a non-ideal gas
    • Abstract: Publication date: Available online 17 March 2019Source: Acta AstronauticaAuthor(s): Amit Tomar, Rajan Arora, Antim Chauhan We studied the problem of converging cylindrical and spherical strong shock waves collapsing at the axis/center of symmetry for a non-ideal gas with constant density. We have applied the perturbation series technique which provides us a global solution to the implosion shock wave problem yielding the results of Guderley's local self-similar solution, which is valid only in the vicinity of the axis/center of implosion. We analyzed the flow parameters by expanding the solution in powers of time and found the similarity exponents as well as the corresponding amplitudes in the vicinity of the shock-collapse. The flow parameters and the shock trajectory have been drawn in the region extending from the piston to the center of collapse for different values of adiabatic coefficient and the non-ideal parameter.
       
  • Aeroheating reduction for blunt body using aerodome jet
    • Abstract: Publication date: Available online 16 March 2019Source: Acta AstronauticaAuthor(s): Qihao Qin, Jinglei Xu A novel thermal protection concept that combines the aerodome and cooling nitrogen is introduced for aeroheating reduction in high-speed flights. Study involves the fluid–thermal interaction between the blunt body and surrounding fluid. After detailed grid and time step verification and numerical validation with available experimental results, the influence of jet pressure and jet distance on the aeroheating reduction performance are analyzed comprehensively. Results indicate that the advantages of the novel combination of aerodome and cooling nitrogen over the conventional opposing jet are mainly embodied in the following three aspects. Firstly, the stability of both the aerodome-jet and the flow field structure can be ensured in wide ranges of flight speed and jet pressure, due to the existence of aerodome. Secondly, on the premise of providing overall thermal protection for the blunt body, emphasis is placed on the direct and continuous cooling of the front part of the blunt body where severe aeroheating occurs. Thirdly, the thermal protection performance can be improved without sacrificing the drag reduction performance by selecting a suitable set of jet pressure and jet distance.
       
  • Extended time-delay autosynchronization method for libration control of
           electrodynamic tether using Lorentz force
    • Abstract: Publication date: Available online 16 March 2019Source: Acta AstronauticaAuthor(s): Yu-wei Yang, Hong Cai It is well known that the libration motion of the electrodynamic tether is unstable. Libration control of the electrodynamic tether system using the Lorentz force produced by current in the tether is studied. In the libration dynamic equation, the Lorentz force is virtually divided into two parts. One part takes the role of keeping the essential function of the electrodynamic tether system. The other part takes the role of controlling the libration motion. The control scheme of the Lorentz force is based on the extended time-delay autosynchronization method. In this scheme, the control current which is the control parameter is determined by real-time states of libration and angular velocities for delay time of previous periods. The validity of the control scheme proposed in this study is confirmed by numerical simulations in the case of circular orbit, elliptical orbit, orbit in the equatorial plane and noises existing in measuring the states of libration. The results show that the perturbed libration motions converge to the periodic solution with time growing in examples of circular orbit, elliptical orbit, and noises existing. The perturbed libration motion converges to an approximate periodic orbit in the example of equatorial orbit. The control current is in a reasonable range during the process of control, and converges to zero in the end. The curve of the current in the tether is continuous and smooth which can be easily achieved in an actual system.
       
  • Atmosphere composition control during long-duration space missions
    • Abstract: Publication date: Available online 16 March 2019Source: Acta AstronauticaAuthor(s): G.Yu. Grigor'iev, A.S. Lagutin, Sh.Sh. Nabiev, A.A. Vasiliev, O.I. Orlov, L.N. Mukhamedieva, A.A. Pakhomova, A.V. Rodin, V.M. Semenov, D.B. Stavrovskii, M.G. Golubkov A concept and strategy of the monitoring of chemical composition of the atmosphere in manned spacecrafts applicable during long-term and interplanetary flights are considered. The suggested concept and strategy are applicable for the life support system in spacecraft, which includes a system of gas composition support, a water supply system, a system of sanitary and hygienic support, a food supply system and a thermal control system. Major risk factors related with changes of the atmosphere composition during interplanetary space missions are evaluated.An advanced design of the analytical complex is described for the control of air quality in manned spacecraft's taking into account these risk factors. The simultaneous use of several methods of gas analysis is proposed together with partial overlapping of the set of substances to be detected with regard to the substances of particular (critical) importance. Application of such gas control system will provide a tool for the analyzing of a wide range of substances and will ensure the analysis of the atmosphere even in case of the failure of some of its parts.
       
  • Selective Laser Melting of a 1U CubeSat structure. Design for Additive
           Manufacturing and assembly
    • Abstract: Publication date: Available online 15 March 2019Source: Acta AstronauticaAuthor(s): Alberto Boschetto, Luana Bottini, Marco Eugeni, Valerio Cardini, Gabriel Graterol Nisi, Francesco Veniali, Paolo Gaudenzi The aerospace industry has used Additive Manufacturing (AM) since its beginnings in the ‘80s because of its unique capabilities. The present work shows a re-designing and the manufacturing via AM of the structural sub-system of a CubeSat from the nanosatellite class. Specifically, a 1U CubeSat design proposal has been developed according to Design for Additive Manufacturing (DFAM) guidelines, considering the consolidation of the parts for reducing and/or avoiding the assembly issues. A configuration made of only two parts has been successfully fabricated via Selective Laser Melting (SLM) technology. AM capabilities allowed to integrate a hinge mechanism in the design, making the resulting structure an already-assembled one. Moreover, the design exhibits snap-fit features in order to get rid of fasteners. The increased complexity of the parts due to the integration of the additional snap-fit features results in no manufacturing issues due to the AM capability to manage shape complexity. This work points AM out as a key technology allowing for a drastic reduction of the part count for a mechanical system, taking Design for Assembly (DFA) guidelines to the extreme. It underlines the need to consider AM-related constrains already in the design phase, such as the clearance and the shape of the hinge and the snap joint matching SLM specific constraints such as support structures design and removal planning, part orientation in the building platform, and hollowing out for powder removal.
       
  • Geostationary station-keeping with electric propulsion in full and failure
           modes
    • Abstract: Publication date: Available online 14 March 2019Source: Acta AstronauticaAuthor(s): Lincheng Li, Jingrui Zhang, Yanyan Li, Shuge Zhao This paper focuses on geostationary satellites with an electric propulsion system and develops two efficient station-keeping strategies in full and failure modes. High-precision mean orbital elements are calculated by an estimator and used as the inputs of two control strategies. In the full mode, an optimization-based maneuver planner, which requires the computations of future orbits, is proposed to achieve long-term minimum-fuel station-keeping. In the failure mode, a fault detection algorithm is designed to diagnose the thruster failure and compute the orbital deviation caused by faulted thruster. Subsequently, a real-time control law as well as a threshold function is formulated to produce the on-off commands of electric thrusters, which correct the orbital deviation. Finally, numerical simulations are made to validate the accuracy and efficiency of two strategies.
       
  • High-frequency electromagnetic radiation affecting moving conductive
           screens
    • Abstract: Publication date: Available online 14 March 2019Source: Acta AstronauticaAuthor(s): M.N. Smirnova, V.V. Tyurenkova, S.N. Kosinov, V.F. Nikitin Protection of on board electronic devises subjected to high-frequency electromagnetic emission is a crucial problem of Space flight safety. The present paper contains the results of theoretical investigation of the effects of high frequency electromagnetic radiation on a moving conductive screen. Methods are developed and results are presented aimed at evaluating conductive screen protective properties depending on thermophysical and electromagnetic properties of material, radiation intensity and frequency, as well as relative velocity of the radiation source and the target.
       
  • Numerical study of a novel monolithic heat exchanger for electrothermal
           space propulsion
    • Abstract: Publication date: Available online 14 March 2019Source: Acta AstronauticaAuthor(s): F. Romei, A. Grubisic Fully-coupled multiphysics simulations are applied to investigate a number of candidate heat exchanger materials in the Super-High Temperature Additively-Manufactured Resistojet (STAR) thruster. Two mission applications are considered: a low earth orbit (LEO) primary propulsion application and a secondary reaction control system (RCS) application of an all-electric geostationary (GEO) telecommunications platform. High-temperature operation provides a significant increase in specific impulse over the state-of-the-art Xenon-resistojets. Inconel 718 is investigated for moderate-performance for LEO applications, while pure tantalum and pure rhenium are examined for the extreme temperature high-performance GEO application. Simulations determine the attainable performance including heat transfer, Navier-Stokes continuum flow and Joule heating physics in both transient and steady state. Nozzle efficiency, heat exchanger efficiency, electrical characteristics and other key performance indicators are explored.
       
  • Penetration mode effect on thermal protection system by opposing jet
    • Abstract: Publication date: Available online 13 March 2019Source: Acta AstronauticaAuthor(s): Jie Huang, Wei-Xing Yao, Zhi-Ping Jiang The effect of the penetration mode on the thermal protection system by opposing jet is studied in this paper. The results show that the opposing jet not only pushes the bow shock away from the blunt body and reduces the shock intensity, but also directly cools the blunt body by the low-temperature jet gas. Therefore, the opposing jet can significantly reduce the aerodynamic heating of the blunt body. When the total pressure ratio of the opposing jet is less than critical value, the opposing jet presents the long penetration mode. When the total pressure ratio is greater than critical value, the opposing jet presents the short penetration mode. The critical total pressure ratio gradually decreases with the increase of diameter of the opposing jet. Increasing the total pressure ratio and diameter of the opposing jet can improve the thermal control efficiency of the opposing jet, and increasing diameter of the opposing jet can also reduce the drag coefficient. However, the drag coefficient increases abruptly when the penetration mode changes.
       
  • Study on the damping capacity of a fluidic baffle under different
           injection conditions
    • Abstract: Publication date: Available online 13 March 2019Source: Acta AstronauticaAuthor(s): Wooseok Song, Jongkwon Lee, Jaye Koo Passive control methods have been widely used to decrease the intensity of combustion instability, and a structural baffle injector has been applied in liquid rocket-engine development. However, the development cost of a structural baffle injector increases because the thrust of a liquid rocket engine should increase as the weight increases. The objective of this paper is to analyze the damping capacity of a fluidic baffle injector using a dissimilar injector arrangement. In this study, a cold-flow test was conducted to observe the effect of using a fluidic baffle injector, and a pulse gun was adopted to generate the pressure wave. A gas-centered swirl coaxial injector and a shear coaxial injector were used to inject the bipropellant. Gaseous nitrogen and liquid water were used for the bipropellant. In addition, multi injectors and a pulse gun were used to compare the effects of a gas-centered swirl coaxial injector and a shear coaxial injector, each acting as the fluidic baffle, on the spray intensity under different conditions. When the gas-centered swirl coaxial injector was used as the fluidic baffle injector, the amplitude increase rate increased as the momentum flux ratio decreased. However, the shear coaxial injector obstructed the pressure-wave propagation. Therefore, the shear coaxial injector was a better fluidic baffle injector than the gas-centered swirl coaxial injector.
       
  • Effects of particle size on two-phase flow loss in aluminized solid rocket
           motors
    • Abstract: Publication date: Available online 13 March 2019Source: Acta AstronauticaAuthor(s): Ziyan Li, Ningfei Wang, Baolu Shi, Shipeng Li, Rongjie Yang This study investigates the two-phase flow loss in aluminized solid rocket motor (SRM) by addressing the effects of particle size. A simplified axisymmetric 2D numerical simulation model is developed to simulate the flow field of the SRM, in which the two-phase flow consists of seeded inert Al2O3 particles and burned gas. The numerical model is verified by lab-scale SRM tests. The results show that the numerical simulation predicts SRM performance accurately when quantitatively capture the true particle size. Based on numerical simulations over a broad range of particle diameters, the effects of particle size on the gaseous phase and particle velocity distributions, particulate trajectories, and the thrust coefficient are systematically examined. It is found that with the same mass content of inert particles the two-phase flow loss decreases with increasing particle size.
       
  • Nutation damping and spin orientation control of tethered space debris
    • Abstract: Publication date: Available online 12 March 2019Source: Acta AstronauticaAuthor(s): Xin Sun, Rui Zhong As a preliminary of an active debris removal process, the attitude motion control of the debris need to be carried out to ensure security of following operations. The tethered space system is one of the most attractive methods for active debris removal missions. However, the tether tension becomes the only input to manipulate the attitude motion of the debris, causing a highly underactuated problem. Fortunately, the fully attitude stabilization of the debris is not a prerequisite for a secure deorbit operation. As long as the nutation of the debris is not so violent that makes the tether winds, the towing process can be applied continually, which is a significant advantage of the tether method. In this paper, a switched tension control law is presented to damp the nutation of the debris. Only two constant tension values are needed in the control method. Under the assumption that the tether direction is fixed in the inertia frame, the bounded stability of the control algorithm is proved based on the Barbalat's Lemma, and an asymptotic stability can be achieved for an asymmetrical debris symmetrically captured. Numerical simulations with tether libration considered are carried out to show the capability of the control method.
       
  • Investigation of ignition characteristics in a kerosene fueled supersonic
           combustor
    • Abstract: Publication date: Available online 12 March 2019Source: Acta AstronauticaAuthor(s): Ye Tian, Shunhua Yang, Baoguo Xiao, Fuyu Zhong, Jialing Le Ignition characteristics of a kerosene fueled supersonic combustor has been numerically and experimentally investigated in the present paper. Flame luminosity images and wall pressure measurements are used for better understanding the ignition and combustion characteristics, air throttling is used to enhance ignition in the combustor. The results are obtained under the inflow condition of Ma number 2.0, total pressure 1.0 MPa and total temperature 1100 K which corresponds to Ma4.5 flight condition. When the ER (Equivalence Ratio) of kerosene is 0.19, the kerosene cannot be ignited at all only by the spark plug. When the flux ratio of air throttling (the ratio of mass flux of air throttling to mass flux of the inflow air) is 9.1%, a small part of kerosene can be ignited, but the flame is blown off soon. When the throttling air flux ratio is increased to 13.7% or 24.5%, the kerosene can be ignited successfully, and the combustion is stable and intense. Cold room temperature liquid kerosene can be ignited successfully by the spark plug with the aid of the throttling air.
       
  • Dual-arm coordinated capturing of an unknown tumbling target based on
           efficient parameters estimation
    • Abstract: Publication date: Available online 12 March 2019Source: Acta AstronauticaAuthor(s): Jianqing Peng, Wenfu Xu, ErZheng Pan, Lei Yan, Bin Liang, Ai-guo Wu A malfunctioned satellite or other space debris is generally non-cooperative and tumbling, bringing great challenge to capture and remove it. In this paper, we propose a dual-arm coordinated capturing method based on efficient parameters estimation. Firstly, the dynamics model of a tumbling target is deduced in details. Its motion characteristics are then analyzed. Secondly, we design an efficient Hybrid Kalman Filter (HKF) by combining Extended Kalman Filter (EKF) with Unscented Kalman Filter (UKF). It effectively overcomes the shortcoming of low accuracy of EKF and long iteration time of UKF, and improves the speed and accuracy of the Kalman Filter iteration algorithm. Two movement cases of an uncontrolled target are considered: one is rotation around the principal axes of inertia; the other is rotation around arbitrary axes. Thirdly, the estimated motion and inertia parameters are used to plan the trajectories of a dual-arm space robot to capture the tumbling target. Finally, the simulation environment is created and the proposed method is verified. The simulation results show that the proposed HKF algorithm can estimate the attitude quaternion, angular velocity, and the inertia tensor (including Ixx, Iyy, Izz, Ixy, Ixz and Iyz) with higher accuracy (compared to EKF) and lower computation cost (compared to UKF); the planned trajectories of the dual-arm space robot are effectively for tumbling target capturing.Graphical abstractImage 1
       
  • Visibility optimization of satellite constellations using a hybrid method
    • Abstract: Publication date: Available online 12 March 2019Source: Acta AstronauticaAuthor(s): Chao Han, Shengzhou Bai, Sihang Zhang, Xinwei Wang, Xiaohui Wang For the visibility optimization problem of satellite constellations, this paper presents an efficient hybrid optimization method taking multiple constraints into account. To reduce the time needed for the optimization, the satellite constellation is assumed to have a specific configuration. The optimization includes two steps. The first step searches for optima over a large scale, while the second step is designed to obtain the accurate optimal solution based on the result of the first-step optimization. Based on the analysis of the coverage performance function, a linear adaptive population method is proposed for the first step. When compared with the traditional optimization method, calculation time can be efficiently reduced while ensuring an accurate optimization. Several numerical simulations are conducted for validation. It proves to be a practical choice for engineering applications.
       
  • A novel approach for design and analysis of volume-improved
           osculating-cone waveriders
    • Abstract: Publication date: Available online 12 March 2019Source: Acta AstronauticaAuthor(s): Li-li Chen, Xiao-long Deng, Zheng Guo, Zhong-xi Hou, Wen-kai Wang A novel design methodology for waverider is proposed based on the conical flow field, named volume-improved osculating-cone waveriders. The new waverider is generated through three given curves, including flow capture curve, inlet capture curve, and curve of the center of exit shock. To meet more design requirements, the curve of the center of exit shock, which can be flexibly designed, is newly introduced to generate configurations with different properties and performances. The feasibility and effectiveness of the method have been verified by computational fluid dynamics (CFD) simulation. The discrepancies between the volume-improved osculating-cone waverider and conventional waveriders are numerically analyzed in detail. The results demonstrate that the new waverider takes the advantage of the volumetric efficiency with little loss of performance compared to the conventional waveriders in design conditions. Furthermore, the results of the off-design conditions show excellent aerodynamic performance as the conventional waverider. Moreover, for bluntness with a radius of 10 mm, the new waverider synthetically owns higher viscous lift-to-drag ratio and greater volumetric efficiency than conventional configurations at 0° angle of attack. Therefore, the novel approach is useful to design the hypersonic waverider vehicle.
       
  • Attitude control of Low Earth Orbit satellites by reaction wheels and
           magnetic torquers
    • Abstract: Publication date: Available online 9 March 2019Source: Acta AstronauticaAuthor(s): G. Avanzini, E.L. de Angelis, F. Giulietti, N. Serrano The purpose of this paper is the design and the performance analysis of a control technique that allows simultaneous attitude control and angular momentum management for a Low Earth Orbit satellite equipped with a set of three magnetic actuators and three reaction wheels. A Proof of global asymptotic stability is derived for a control law driving a rigid spacecraft towards a prescribed, yet generic attitude fixed in the orbit frame. An analytical technique allowing for control gain selection is also proposed, which provides optimal convergence performance for the proposed controller, as demonstrated by means of Monte Carlo simulations. Robustness to external disturbances is finally evaluated within a realistic implementation scenario.
       
  • The shock environment prediction of satellite in the process of
           satellite-rocket separation
    • Abstract: Publication date: Available online 9 March 2019Source: Acta AstronauticaAuthor(s): Hongda Zhao, Zhiwei Hao, Wei Liu, Jifeng Ding, Yi Sun, Qiuhua Zhang, Yizhi Liu This paper mainly discusses the shock environment prediction of the satellite in the process of satellite-rocket separation. At first, the field near to the shock source (near-field) that contains the pyrotechnic separation nut, satellite joint and rocket joint is researched with separation shock experiment and explicit dynamic code LS-DYNA. And then, the satellite model (far-field) is introduced. The force curve at the interface of satellite joint and the adjacent angle steel in vertical direction is extracted and used as the input of shock environment of satellite. Furthermore, the shock environment of the bottom panel and the side panel of the satellite in the flexure direction are computed by Virtual Mode Synthesis Simulation (VMSS). The results are compared with the ones of Finite Element Method (FEM). At last, the deficiencies of VMSS on the shock environment prediction of the satellite panel in the extension and shear directions are revealed since they do not contain enough modal number. The completed shock environment prediction method proposed in this paper is expected to provide a reference for the rapid and accurate computation of the shock environment at the initial stage of satellite structure design.
       
  • Acceleration of a 2D unsteady Euler solver with GPU on nested Cartesian
           grid
    • Abstract: Publication date: Available online 9 March 2019Source: Acta AstronauticaAuthor(s): Feng Wei, Liang Jin, Jun Liu, Feng Ding, Xinping Zheng Graphics processing unit (GPU) parallel computation is used to accelerate a solver, which computes the 2D unsteady compressible Euler equation discretized with the finite-volume method on a nested Cartesian grid. In this solver, a second-order accurate upwind scheme is adopted, with explicit time-stepping by using the third-order total-variation-diminishing Runge–Kutta method. An improved parallel strategy is implemented, and through dealing with a test case on a three-level nested Cartesian grid, speedup ratios of 9.98–14.04 are achieved respectively at different grid sizes. Furtherly, through a numerical experiment, the relation between the kernel performance and the execution configuration at different grid sizes is examined by monitoring and analyzing the performance indicators. Moreover, approaches to improve kernel performances are explored.
       
  • Two-photon absorption laser induced fluorescence with various laser
           intensities for density measurement of ground state neutral xenon
    • Abstract: Publication date: Available online 8 March 2019Source: Acta AstronauticaAuthor(s): Kiyoshi Kinefuchi, Yoshio Nunome, Shinatora Cho, Ryudo Tsukizaki, Tat Loon Chng Electrostatic plasma thrusters such as ion engines and Hall thrusters commonly use xenon as a propellant and several measurement techniques for xenon ions and metastable neutrals have been applied to evaluate the characteristics of the thrusters. Although density measurements of ground state neutral xenon can provide crucial information on the ionization characteristics and help explain charge exchange phenomenon, much less research is available due to its technical difficulty. Two-photon absorption laser induced fluorescence is promising because it allows access to ground state xenon atoms by using around 220–260 nm wavelength lasers which have become more readily available lately. In this study, observation of the fluorescence following two-photon excitation from a room temperature (cold) xenon gas cell is conducted with 249 and 252 nm wavelength excitation at xenon pressures of 0.1 and 10 Torr. The fluorescence signals are obtained against a wide range of laser intensities, and the resulting fluorescence response comprises of a few regimes – weak-excitation, saturation, and an intermediate regime. The natural lifetime and quenching rate are evaluated by analyzing the fluorescence decay, and the result is consistent with published literature. Finally, actual application to ground tests of Hall thrusters is discussed based on the experimental results, especially with respect to their fluorescence responses.
       
  • Search-based method optimization applied to bi-impulsive orbital transfer
    • Abstract: Publication date: Available online 7 March 2019Source: Acta AstronauticaAuthor(s): Mohammad Sanatifar, Roberto Capuzzo-Dolcetta In this paper optimal bi-impulse orbital transfer between coplanar and non-coplanar elliptical orbits has been considered. First, an efficient algorithm based on grid search method has been developed to find the global solution of the impulsive orbital transfer. There are three independent parameters in this algorithm: i) the angular position of the point on the initial orbit where the first impulse is applied to, ii) the angular position of the point on the final orbit where the second impulse is applied to and, iii) the argument of periapsis of the transfer orbit. The other parameters can be obtained from these three parameters in both coplanar and non-coplanar cases. The algorithm is able to obtain the global optimal solution for any arbitrary initial and final elliptical orbits. Second, the algorithm is employed to solve an extensive set of numerical examples, including coplanar and non-coplanar, co-axial and non-co-axial orbits of different shape and energy. This comprehensive set of examples allows disentangling the roles of each relevant orbital parameter in the evaluation of the optimal transfer. Finally, the numerical results are employed to achieve a very precise fitting function which is helpful onboard calculation and mission design.
       
  • Drag and heat flux reduction induced by the pulsed counterflowing jet with
           different waveforms on a blunt body in supersonic flows
    • Abstract: Publication date: Available online 7 March 2019Source: Acta AstronauticaAuthor(s): Rui-rui Zhang, Wei Huang, Li Yan, Zheng Chen, R. Moradi The drag and heat flux reduction characteristics plays a very important role in the conceptual design phase and engineering realization of the aerospace vehicle. In the current study, the flow field properties around a blunt body with three different pulsed counterflowing jets in the supersonic flow with the freestream Mach number being 3.98 are investigated numerically. In this paper, there are three different kinds of pulsed jets with the sinusoidal, triangular and rectangular waveforms are established, and the periods of the pulsed jets are all set to be T = 1.0 ms. The jet nozzle is placed at the nose of the blunt body. In the numerical investigation, an axisymmetric numerical simulation model of the counterflowing jet on the supersonic vehicle nose-tip is established, and the two-dimensional axisymmetric Reynolds-averaged Navier-Stokes (RANS) equations coupled with the two equation k-ω shear stress transport (SST) turbulence model are employed. The wall Stanton number distributions, as well as the surface static pressures, are extracted from the flow field structures in order to evaluate the drag and heat flux reduction characteristics. Further, the influence of the pulsed jet waveform on the drag and heat flux reduction is analyzed based on the wall Stanton number and surface pressure distributions. The obtained results show that the variations of the wall Stanton number and surface pressure distributions induced by the pulsed jet with the same period but different waveforms, all have an obvious periodicity and hysteresis phenomenon. At the same time, it is found that the drag and heat flux reduction under the triangular wave has the best effect, and the pulsed jet with the triangular wave has a better comprehensive performance than the other two waveforms.
       
  • Evaluation of aerospike for drag reduction on a blunt nose using
           experimental and numerical modeling
    • Abstract: Publication date: Available online 7 March 2019Source: Acta AstronauticaAuthor(s): Mohamad Kazemi Esfeh, Seyed Mohamad Tajalli, Pengfei Liu The modification of high-speed flight vehicles by adding a spike attached to the stagnation point yields a complex flow-field full of interesting details. The purpose of this work is to contribute to the following two aspects. First, to analyze the interaction between oblique shock, separation shock and reattachment shock to explain the mechanism of drag reduction caused by the spike. Second, to assess the impact of varying the spike length (L/D = 0.5, 1.0 and 1.5), angle-of-attack (up to 10°) and Mach number (up to 3) on the level of drag reduction. The results reveal that, by comparing with the un-spiked blunt nose, the maximum drag reduction is 42% for L/D = 1.0 at α = 0°. For higher angles-of-attack, the spike is found to have little benefits in reducing the drag. Moreover, the efficiency of the spike in reducing drag and increasing lift depends largely on spike length. However, the spike length does not influence the aerodynamic coefficients when it exceeds the value of the blunt-body diameter ratio (L/D = 1.0).
       
  • Factor structure and validation of the mental health checklist (MHCL) for
           use in isolated, confined and extreme environments
    • Abstract: Publication date: Available online 7 March 2019Source: Acta AstronauticaAuthor(s): Joanne L. Bower, Mitzi S. Laughlin, Christopher Connaboy, Richard J. Simpson, Candice A. Alfano Although human psychological risks gravely threaten the safety and success of future Mars missions, current knowledge of the mental health problems most likely to manifest during long duration space exploration (LDSE) is surprisingly inadequate. Previous research conducted during spaceflight and in analog settings has produced discrepant, sometimes contradictory findings and relied on measures that have not been validated for use in extreme environments, where the number, intensity, and duration of stressors exceed typical human experience. We therefore developed the Mental Health Checklist (MHCL) based on subject matter interviews and comprehensive literature reviews. In study one, exploratory and confirmatory factor analyses resulted in 3 reliable subscales (positive adaptation, poor self-regulation, and anxious apprehension) explaining 53% of the total variance. In study two, we examined the reliability and convergent validity of the MHCL in large sample of participants stationed in Antarctica. Findings suggest the MHCL to have acceptable psychometric properties for use in extreme settings. We encourage other researchers to incorporate the MHCL in future studies, including spaceflight research, and to examine its sensitivity for capturing intra-individual symptom changes over time.
       
  • Effects of rapid depressurisation on the structural integrity of common
           foodstuffs
    • Abstract: Publication date: Available online 6 March 2019Source: Acta AstronauticaAuthor(s): Charles S. Cockell, Scott McLaughlin In preparation for the eventual manufacture and storage of food in space, we conducted a set of experiments to determine the effect of a rapid catastrophic depressurisation on a range of common foodstuffs. The experiment tested the hypothesis that rapid depressurisation would cause explosive destruction or boiling of stored foodstuffs. We tested 18 types of fruit, 18 types of vegetables, 4 types of nuts, 4 types of fish, 10 types of raw and prepared meat, chicken eggs, 9 types of cheese and 8 other foods including rice and lentils. They were exposed to depressurisation from atmospheric pressure to 6 mb in 5.67 min to simulate a rapid depressurisation event on Mars. We found most of the tested produce to be robust against depressurisation. No explosive rupture or failure was observed in any of the tested items. Introduction of cuts into the produce resulted in localised bubbling, for example in tomatoes, and bubbling was observed at the site of bruising, for example in bananas and pears. At pressures greater than ∼30 mb we attribute this to outgassing and below this pressure to a combination of outgassing and boiling and we present a general model to describe these findings. Raw meat (such as ham), fish (such as salmon) and some cheeses (such as Mozzarella) bubbled at their surfaces, causing the surface to dry. The most profound changes were observed in sausages, haggis and chicken in which air expanded beneath the skins, stretching the skin and causing wrinkling when repressurisation occurred, although the overall integrity of the food was not altered. We conclude that a rapid depressurisation event in a food storage unit would not cause catastrophic physical disruption of food. However, secondary protection inside closed containers is advisable for fish, raw and prepared meats, fruits and vegetables with observable bruising or damage, to protect against drying during a depressurisation event. Our data show the potential for low pressure storage of food.
       
  • Experimental study and numerical simulation of chemiluminescence emission
           during the self-ignition of hydrocarbon fuels
    • Abstract: Publication date: Available online 6 March 2019Source: Acta AstronauticaAuthor(s): A.M. Tereza, S.P. Medvedev, V.N. Smirnov The time evolution of the chemiluminescence emission signals of CH*, OH*, C2*, and CO2* during the self-ignition of a number of the simple hydrocarbons is studied. The experiments are performed behind reflected shock waves over a temperature range of 1100–1900 K at a pressure of ∼1 bar. The effects of fuel-to-oxidizer equivalence ratio and the structure of the hydrocarbon molecule on the time profiles of the signals for each of the emitters are examined. A detailed kinetic mechanism for describing the emission signals from CH*, OH*, C2*, and CO2* recorded during the self-ignition of hydrocarbons is developed. To make the simulations more rigorous and reliable, the NASA thermodynamic polynomials for C2*, and CO2* were calculated based on the respective rotational and vibrational parameters given in the literature. Numerical simulations satisfactorily reproduce the measured time profiles of the signals from the studied emitters.
       
  • Statistical behavior of shear layers of reactive oxygen/kerosene spray
    • Abstract: Publication date: Available online 6 March 2019Source: Acta AstronauticaAuthor(s): Songyi Choi, Junsun Ahn, Jaye Koo Reactive gaseous oxygen/kerosene spray was visualized by a shadowgraph imaging technique in a lab-scale rocket engine combustor. Dynamic behaviors of inner and outer shear layer were observed morphologically and analyzed quantitatively by image processing. Correlation methods were used to statistically analyze dynamic behaviors of each shear layer and interaction between two shear layers. Relationship between shear layer dynamics and combustion flow-field was investigated by analyzing periodicity of jet-core length, lump-detachment, and luminous flame intensity. The results of correlation and frequency analysis show that dominant frequency of behaviors and interaction of shear layers is 270 Hz and the degree of correlation becomes stronger along the flow direction. The dominant frequency of core length variation and luminous flame formation is around 270 Hz and, which is the same as that of behaviors and interaction of shear layers. This proposes that the surface behaviors and interaction of the inner and outer jets in the upstream affect the downstream combustion flow-field.
       
  • Research of the explosive formation of a compact element for meteoroids
           fragments and space debris modelling
    • Abstract: Publication date: Available online 6 March 2019Source: Acta AstronauticaAuthor(s): V.V. Selivanov, S.V. Fedorov, Ya M. Nikolskaya, S.V. Ladov X-ray research of particles formed during the explosion of a shaped charge with steel liner of the combined hemisphere-cylinder shape with a jet-forming part of a degressive (decreasing from top to base) thickness and a cylindrical part is carried out. It was experimentally confirmed that the transition from the constant to the degressive thickness of the hemispherical part of the liners allows to increase the velosity of the head section of the material formed during its compression by the jet flow of the material, which is cut off during the collapse of the cylindrical part of the liner. The velosity of a steel compact non-gradient element recorded in experiments for tested variants of a shaped charge was 7.8 … 8.6 km/s, which, within the permissible experimental errors, corresponds to the results of previously performed numerical calculations and approximately 30% higher than the speed of the corresponding element obtained using constant thickness.
       
  • Articulated linkage arms based reliable capture device for janitor
           satellites
    • Abstract: Publication date: Available online 6 March 2019Source: Acta AstronauticaAuthor(s): Junwoo Choi, Jinwon Jung, Dongkyu Lee, Byungkyu Kim As the number of operational satellites in orbit has dramatically increased, orbiting space debris has become a serious problem. To solve this problem, de-orbiter studies have been conducted to eliminate space debris and inactive satellites. Other studies have proposed the use of janitor satellites which capture and deorbit inactive satellites. This study further develops the janitor satellite idea and proposes a specific capture device design to retrieve space debris and obsolete orbiting devices. In order to capture a wide range of target objects with various sizes and shapes securely, the proposed design features articulated arms consisting of a series of jointed segments. Each segment in the arm structure is a different length, which allows the device to capture targets of different sizes. The device linkages are driven by two motors pulling on a Kevlar cord, and a latching mechanism is employed as a redundant component in the event the Kevlar cord loses tension, ensuring continuous operation. A static analysis is performed to determine the motor power for capture device and force requirements for latching mechanism. Based on the results of theoretical analysis, the capture device is fabricated, and functional tests are carried out. In addition, the reliability of the capture device is investigated based on reliability analysis using one-shot device evaluation method. As a result, device reliability rate was calculated as 0.999841. Conclusively, more than 20 times deployment and capturing experiments are successfully performed.
       
  • Autonomous navigation for GPS using inter-satellite ranging and relative
           direction measurements
    • Abstract: Publication date: Available online 6 March 2019Source: Acta AstronauticaAuthor(s): Feng Yu, Zhen He, Na Xu This paper proposes a new method utilizing both inter-satellite ranging and relative direction measurements to realize autonomous ephemeris update of navigation satellites. The relative direction from one satellite to another is determined by utilizing a normal star sensor. A GPS satellite is equipped with a beacon which can produce a light beam. The light beacon is of sufficient apparent magnitude to be imaged by the star sensor mounted on the following GPS satellite in the same orbital plane. Only the software of star sensor needs to be improved to detect the stars and the light beacon simultaneously. Firstly, the light power consumption is analyzed, and the station keeping requirements are derived from the geometrical relationship between the light beam angle and orbit phase error. Secondly, a preprocessing procedure utilizing the Gauss-Newton iteration method is developed to determine the relative direction by using all the visible stars in the field-of-view of star sensor. Thirdly, an extended Kalman filter is developed to estimate the positions of all the GPS satellites by using both the ranging and the relative direction measurements. Finally, numerical simulations are executed to verify the validity of the proposed method.
       
  • Periodic and quasi-periodic orbit design based on the center manifold
           theory
    • Abstract: Publication date: Available online 28 February 2019Source: Acta AstronauticaAuthor(s): Yuki Akiyama, Mai Bando, Shinji Hokamoto This paper proposes a new numerical method for finding libration point orbits in the vicinity of collinear libration points in the circular restricted three-body problem. The main advantage of this method is that it requires neither an initial guess nor complex algebraic manipulations for finding both quasi-periodic and periodic orbits. The proposed method consists of two steps: center manifold design and differential correction. The first step provides a quasi-periodic orbit parametrized by a single parameter vector. In the second step, the parameter vector in the first step is used to obtain an exact periodic orbit. This method is applied to find periodic and quasi-periodic orbits in the Sun-Earth restricted three-body problem around the L1 and L2 libration points.
       
  • Numerical study of ways to prevent side loads in an over–expanded rocket
           nozzles during the launch stage
    • Abstract: Publication date: Available online 28 February 2019Source: Acta AstronauticaAuthor(s): I.E. Ivanov, I.A. Kryukov The paper aims to study an issues of ensuring the safe launch of spacecraft. The phenomenon of a turbulent boundary layer separation from the rocket engine nozzle wall intensively studied in the overexpansion mode that is realized at the start–up stage at sea–level. The emergence of the so–called restricted flow separation leads to the side loads on the wall of the nozzle, the shaking the structure and the destruction of the engine. The conditions for the realization of restricted or free shock separation in the thrust–optimized contoured nozzles of rocket engines are studied numerically. A hysteresis was obtained when changing the type of separation at the stages of increasing and decreasing pressure at the nozzle inlet with the same ambient pressure. Two ways of controlling the transition from one type of separation to another one were studied numerically. The numerical simulation of separated flow in a model nozzle with a back cone shaped extension was carried out. The numerical results confirm that in the nozzle with the large back cone the restricted shock separation can arise and this result appears to be in agreement with experiment.
       
  • Spacecraft orbit around two fixed bodies
    • Abstract: Publication date: Available online 28 February 2019Source: Acta AstronauticaAuthor(s): M. Kobayashi, K. Yamada Being the simplest case in the three-body problem, the motion of a test particle in the field of two fixed bodies was first considered by Euler in 1760. In celestial mechanics, it represents the motion of a spacecraft that is attracted by two celestial bodies fixed in space and do not influence each other. The motion of the spacecraft is influenced by the gravitational forces of these two fixed bodies. Although the scenario of having two centers fixed in inertial space is not practical, some orbits could be applied in actual missions. This paper considers the above situation with a focus on closed orbits around a body such as a dumbbell-shaped asteroid or a binary body. The aim of this study is to demonstrate a robust method to obtain these orbits. Two types of conceivable motion around two fixed bodies are considered: an elliptic orbital motion and an 8-shaped motion. This paper analyzes the characteristics of these motions, where the mass ratio of the celestial bodies and the distance between them are taken as parameters.
       
  • Observability analysis and autonomous navigation for two satellites with
           relative position measurements
    • Abstract: Publication date: Available online 28 February 2019Source: Acta AstronauticaAuthor(s): Yong Li, Ai Zhang The autonomous navigation of multi-satellite systems using only on-board measurements is a fundamental task in many space missions. The main purpose of this study is to establish new methods for the autonomous orbit determination of a dual satellite system using relative position measurements only. A novel concept, k-order local weak observability, is proposed. Based on unperturbed Kepler orbit dynamics and J2-perturbed orbit dynamics respectively, sufficient and necessary conditions of k-order local weak observability are mathematically proved for the autonomous navigation system. Observability-based modified EKF, modified UKF, and modified SDREF are presented and used as navigation algorithms. Simulation results illustrate the performance of the developed navigation algorithms in comparison with the traditional EKF, UKF, and SDREF.
       
  • Modeling the equations of state using a flamelet approach in LRE-like
           conditions
    • Abstract: Publication date: May 2019Source: Acta Astronautica, Volume 158Author(s): Pasquale Eduardo Lapenna, Giuseppe Indelicato, Rachele Lamioni, Francesco Creta In this study, we investigate the averaging and modeling of real fluid equations of state (EoS) used in the context of numerical simulations of flows under conditions relevant to liquid rocket engine (LRE) thrust chambers. Direct numerical simulation (DNS) data of supercritical and transcritical mixing are used, in an a-priori fashion, to glean insight on the effect of averaging the EoS in the context of Reynolds averaged Navier Stokes (RANS). The widely employed no-model approach for the EoS, which neglects residual effects, is shown to generate large errors under transcritical conditions due to the extreme non-linearity of the pseudo-boiling processes. Further a-priori analysis, performed by filtering the DNS data in a large eddy simulation (LES) context, shows that highly resolved LES mitigates such sub grid scale errors. We discuss such EoS modeling related issues in the context of flamelet based turbulent combustion approaches and low Mach number assumptions, under which they acquire an unambiguous thermodynamic consistency. We show a-posteriori that a steady laminar flamelet formulation, implemented in a low Mach number unsteady RANS solver, is capable of correctly capturing the characteristic flow field and structure of a reference liquid oxygen (LOx) - gaseous methane (GCH4) cryogenic flame at supercritical pressure.
       
  • Evaluation of the grid convergence for a rocket combustion chamber with a
           porous injector
    • Abstract: Publication date: May 2019Source: Acta Astronautica, Volume 158Author(s): Victor P. Zhukov, Klaus P. Heinrich A study of the grid convergence was carried out in order to quantify the mesh impact on simulations of rocket combustion chambers performed using the averaged Navier–Stokes equations. The present work is a continuation of previous studies on simulations of rocket combustion chambers with the porous injector head API-68. Turbulence is modelled by the SST turbulence model; turbulent combustion is modelled using the extended eddy-dissipation model. The grid convergence study is carried out for two injector configurations (one injector in the middle of the injector head and one injector near the sidewall) on five meshes for each configuration. Results of the work show that the dependences of the flame length and wall heat flux on mesh spacing are described well by a parabola. Using the found dependence on mesh spacing, spatial discretization errors have been evaluated. Analysis of the results shows that a reasonable accuracy of modelling can be reached using the current computational fluid dynamic model at a mesh spacing of around 30 μm in the flame area.
       
  • Complex numerical-experimental investigations of combustion in model
           high-speed combustor ducts
    • Abstract: Publication date: May 2019Source: Acta Astronautica, Volume 158Author(s): Mikhail Ivankin, Alexey Nikolaev, Vladimir Sabelnikov, Anna Shiryaeva, Vadim Talyzin, Vladimir Vlasenko Fast technologies for numerical simulation of high-speed flows in ducts, developed in TsAGI, are described. The examples are presented of the application of experimental data, obtained at T-131 wind tunnel, for validation of the developed numerical technologies: 1) validation of 2.5D and 3D calculations of flow in the elliptic combustor with hydrogen supersonic combustion that was studied within HEXAFLY-INT international project; 2) validation of 2D and 2.5D calculations of flow in high-speed model combustor duct with step-like expansion. Preparation of new series of experiments, oriented on validation of turbulent combustion models, is described.
       
  • Iron oxide as solid propellant catalyst: A detailed characterization
    • Abstract: Publication date: May 2019Source: Acta Astronautica, Volume 158Author(s): F. Maggi, S. Dossi, C. Paravan, L. Galfetti, R. Rota, S. Cianfanelli, G. Marra Hematite represents the most common burning rate modifier used in propellant production. The tuning of burning rate is obtained even for amounts ranging below 1 wt% of the total composition. Different studies have evidenced a role in ammonium perchlorate dissociation while there are not enough literature documents to clearly support or oppose its capability to enhance binder decomposition. The acceptance of such ingredient in an industrial environment is based mostly on the verification of few parameters, relevant to catalytic action (namely, particle size, specific surface area). The complexity of the iron oxide family shows a wide set of features, neglected in standard quality check but important for a detailed characterization. Such properties assist in defining a unique fingerprint of the material and can be used for detailed identification of batch-to-batch reproducibility, for new supplier qualification, or for improvement of basic knowledge. The present paper is an extract of a detailed characterization activity performed on different batches of nominally identical propellant-grade hematite. Reported results show peculiar properties of the ingredients and characterization methodologies specifically employed for the scope, proposing an end-to-end batch analysis for full ingredient back-trace capability in the supply chain.
       
  • Accelerated ageing of micron- and nano-sized aluminum powders: Metal
           content, composition and non-isothermal oxidation reactivity
    • Abstract: Publication date: May 2019Source: Acta Astronautica, Volume 158Author(s): Christian Paravan, Alberto Verga, Filippo Maggi, Luciano Galfetti Nano-sized Al (nAl) is an attractive candidate for the performance enhancement of current solid propellant formulations, and its characteristics are relevant for the development of innovative solid fuels for hybrid rocket propulsion. Nano-sized Al powders feature a higher reactivity than their micron-sized counterpart. While desirable for effective energy conversion during the combustion, this characteristic yields possible powder storage issues. This paper investigates the ageing behavior of air-passivated nAl powders under two different relative humidity conditions (RH) of 80% and 10%. Fresh and aged powders are characterized by active metal content determination (CAl), electron microscopy, X-ray diffraction, and thermal analysis. The marked sensitivity of nAl (40 nm) to ageing is testified by a nearly full CAl loss in just 24 h (with RH = 80%). Under the same condition, the conventional 30 μm-counterpart loses only 13% of the original active metal content in a time of 336 h.
       
  • Preliminary tests on thermal ignition of ADN-based liquid monopropellants
    • Abstract: Publication date: May 2019Source: Acta Astronautica, Volume 158Author(s): Marius Wilhelm, Michele Negri, Helmut Ciezki, Stefan Schlechtriem Preliminary tests on thermal ignition with ADN-based liquid monopropellants FLP-106 and LMP-103S have been conducted using two thermal ignition methods. Investigated thermal ignition methods were based on a pilot flame igniter and a glow plug. Results indicated that ADN-based propellants offer different behavior compared to conventional monopropellants. At first the propellants needed to be conditioned by evaporating the water portion. In this phase the heat transfer from the igniters to the propellant played a major role for the ignition time delay. After evaporation of the water the propellant decomposition could be initiated. It was found that with thermal igniters the internal energy feedback from decomposing propellant portions was insufficient to condition newly injected propellant portions upstream. An external heat feedback is necessary to sustain water evaporation and hence propellant combustion. While tests with a pilot flame igniter and a cylindrical combustion chamber were not successful, glow plug ignition showed satisfying decomposition and ignition behavior. With the conducted preliminary thermal ignition tests a profound knowledge could be gained concerning propellant ignition behavior of FLP-106 and LMP-103S. Furthermore similarities and differences of both propellants could be analyzed and allow improvement of thermal ignition methods for future research activities.
       
  • A MultiPhase Dynamic-VoF solver to model primary jet atomization and
           cavitation inside high-pressure fuel injectors in OpenFOAM
    • Abstract: Publication date: May 2019Source: Acta Astronautica, Volume 158Author(s): F. Piscaglia, F. Giussani, A. Montorfano, J. Hélie, S.M. Aithal This paper describes the development of a dynamic two-phase Volume-of-Fluid (VOF) solver to study the physics of the primary jet breakup and flow transients induced by the nozzle geometry during the injector opening event in high-pressure injection using the OpenFOAM technology. The dynamic solver has been extended to support second-order discretization in time for moving mesh problems with automatic topology changes. The solver extension includes curvature effect in the interface tracking. Phase change at the interface was modeled using the Schnerr and Sauer model. While the solver is compatible with any kind of turbulence model, turbulence effect have been treated using Large-Eddy Simulations (LES). Detailed numerical studies are presented to demonstrate the conservation preservation property and accuracy of the solver. Code validation was performed by comparing numerical results with experiments on a Continental XL 3.0 6-hole prototype injector. Finally, limits of applicability of the cavitation model with a two-phase solver for the simulation of internal nozzle flows of injectors are discussed.
       
  • Development of an intrusive technique for particles collection in rockets
           plume
    • Abstract: Publication date: May 2019Source: Acta Astronautica, Volume 158Author(s): Stefania Carlotti, Filippo Maggi, Alessandro Ferreri, Luciano Galfetti, Riccardo Bisin, Dominik Saile, Ali Gülhan, Christopher Groll, Tobias Langener An intrusive technique for particles capturing in supersonic-high temperature flows to be used in solid rocket motors plume characterization is proposed. A supersonic probe for the collection of the condensed combustion products in the proximity of the rocket nozzle has been designed to handle a progressive deceleration and cooling down of the exhaust gas, aiming at preserving liquid particles from break-up. A quasy-1D gas dynamics software (POLIRocket-V2) based on the Shapiro method and normal shock wave theory, supported by a CFD investigation using the DLR TAU code, was employed for the feasibility and the design study. Preliminary cold flow tests have been performed in the VMK supersonic vertical wind tunnel at DLR in relevant flow conditions. A proofs of concept of the probe working principle and the collection methodology were studied.
       
  • Numerical simulation of radiation in high altitude solid propellant rocket
           plumes
    • Abstract: Publication date: May 2019Source: Acta Astronautica, Volume 158Author(s): Quentin Binauld, Jean-Michel Lamet, Lionel Tessé, Philippe Rivière, Anouar Soufiani Models and computational schemes are presented to simulate the flow field and radiation in solid propellant rocket plumes at high altitude. Different models are developed to calculate plume radiation induced by both the gas and the dispersed phase of alumina particles. Simulations were made to reproduce a 110 km altitude rocket plume and comparisons with experimental data on the plume radiance are presented. Influence of different physical processes on the simulation of the plume flow field and radiation is discussed, such as alumina phase change, scattering and the coupling of radiation with the two-phase flow.
       
  • Design of a film cooled dual-bell nozzle
    • Abstract: Publication date: May 2019Source: Acta Astronautica, Volume 158Author(s): Ralf Stark, Chloé Génin, Christian Mader, Dietmar Maier, Dirk Schneider, Michael Wohlhüter The design of a film cooled dual-bell nozzle is presented. The nozzle is part of a thrust chamber assembly that adopts an existing LOX/GH2 thrust chamber. The dual-bell base nozzle, including the gaseous hydrogen cooling film injection, is a downscaled redesign of an already tested film cooled TIC nozzle. Future hot flow tests at the test facility P8 will study the impact of a ROF variation and a cooling film mass flow variation on the operation mode transition of the dual-bell. For this reason, a homogeneous hot flow and cooling film distribution are mandatory. To meet those demands, extensive numerical studies were performed and design optimizations were derived. The test specimen will be operated under sea level conditions.
       
  • Transition of combustion instability in hybrid rocket by swirl injection
    • Abstract: Publication date: May 2019Source: Acta Astronautica, Volume 158Author(s): Jungeun Kim, Changjin Lee A series of experimental tests was conducted to investigate the effect of swirl injection on the combustion instability in hybrid rocket using combustion visualization technique. As a result, swirl injection seems to modify two main physical processes responsible for the initiation of LFI. First one is the transition of coupling status between two fluctuations of combustion pressure (p') and heat release (q') of 500 Hz band. The transition of p' and q' to negative coupling seems to be a crucial modification for stabilizing the combustion. Another noticeable effect of swirl injection is the gradual increase in the peak frequency of pressure oscillation from its initial value of around 20 Hz–50 Hz band, which is caused by the thermal lag, as the swirl intensity increases. Also, POD (Proper Orthogonal Decomposition) analysis was done to understand flow response to the swirl injection near the fuel surface. The analysis of temporal behavior of mode 1 and 2 suggested that the swirl injection with proper intensity not only suppress the generation of p' of 500 Hz band but induces a shift of low frequency peaks of 20 Hz band by adjusting the turbulent structures in boundary layer. And the shift of low frequency peaks seems to be another contributing factor for combustion stabilization.
       
  • Optical analysis of the liquid layer combustion of paraffin-based hybrid
           rocket fuels
    • Abstract: Publication date: May 2019Source: Acta Astronautica, Volume 158Author(s): Anna Petrarolo, Mario Kobald, Stefan Schlechtriem Liquefying hybrid rocket fuels (e.g. paraffin) enable higher regression rates due to the presence of an unstable melt layer on the fuel surface during combustion, which causes entrainment of liquid droplets into the oxidizer gas flow. In order to better understand the mechanism responsible for the droplets entrainment, the combustion behaviour of paraffin-based hybrid rocket fuels in combination with gaseous oxygen (GOX) was investigated in the framework of this research. Tests were performed in a 2D slab burner configuration at atmospheric conditions. High-speed videos were recorded and analysed with two different decomposition techniques, applied to the scalar field of the flame luminosity (the flame front is assumed to follow the liquid layer). The fuel slab composition and configuration and the oxidizer mass flow have been varied in order to study the influence of these parameters on the liquid layer instability process. The main focus of the research is to understand the relation between the unstable waves which enable the droplets entrainment process and the regression rate. The results show that the combustion is dominated by periodic, wave-like structures for all the analysed fuels. The frequencies and the wavelengths characterizing the liquid melt layer depend on the fuel viscosity and geometry and on the oxidizer mass flow. Moreover, a dependency of the regression rate on the most excited frequencies and longitudinal wavelengths was found. This is important to better understand the relation between the increased regression rate and the onset and development of the entrainment process, which is connected to the amplification of longitudinal unstable waves caused by the high velocity gas flow over the fuel surface.
       
  • Experimental and numerical methods for radiative wall heat flux
           predictions in paraffin–based hybrid rocket engines
    • Abstract: Publication date: May 2019Source: Acta Astronautica, Volume 158Author(s): Giuseppe Leccese, Daniele Bianchi, Francesco Nasuti, Keith Javier Stober, Pavan Narsai, Brian Joseph Cantwell The paper is intended to present both experimental and numerical approaches for estimating the heat exchange through thermal radiation towards the walls of lab–scale paraffin–based thrust chambers. Two firing tests of a lab–scale gaseous–oxygen/paraffin–wax hybrid rocket engine have been performed to apply such methods. In particular, the radiative wall heat flux has been evaluated by both spectroscopic measurements and discrete transfer method computations. Details of such approaches are given together with results achieved. The significant gap between experimental and numerical estimations suggested further investigations of influencing processes, whose main outcomes and lessons learned are critically discussed.
       
  • Experimental investigation of the hydrogen peroxide – solid
           hydrocarbon hypergolic ignition
    • Abstract: Publication date: May 2019Source: Acta Astronautica, Volume 158Author(s): David A. Castaneda, Benveniste Natan The hypergolic ignition of a solid hydrocarbon fuel with hydrogen peroxide has been achieved by embedding catalyst particles into the fuel. Sodium borohydride can enhance ignition of the solid fuel upon contact with 90% hydrogen peroxide. Ignition delay times were measured in drop-on-solid tests at atmospheric and elevated pressure conditions and qualitative descriptions of the hypergolic behavior are given. The results demonstrate that the ignition of the hydrocarbon matrix used (polyethylene) is feasible, especially at high pressures. Ignition delay times of less than 10 ms were observed at atmospheric conditions and less than 5 ms at pressures above 0.5 MPa. Additional tests were performed employing radial oxidizer injection over a hollow cylindrical surface, proving the viability of the concept.
       
  • Effects of heat treatments to inner liner material, thermal barrier
           coating, and outer shell material on lifetime of a combustion chamber
    • Abstract: Publication date: May 2019Source: Acta Astronautica, Volume 158Author(s): Toshiya Kimura, Shin-ich Moriya, Masaharu Takahashi Key factors were investigated to extend the lifetime of a combustion chamber of a large thrust rocket engine. Two-dimensional finite element simulations were conducted to estimate creep damage and low cycle fatigue damage to the inner liner of a combustion chamber wall. In these simulations, the effects of difference of heat treatments to the inner liner material, heat shield by a thermal barrier coating, and thermal expansion of the outer shell on lifetime were examined. It was found that heat shield by a thermal barrier coating had the largest effect in extension of the lifetime though the effect depended on the physical characteristic of the inner liner material. Expansion or contraction of the outer liner during combustion affects the restriction of the inner liner resulting in the extension of the lifetime. By combination of these effects, the lifetime can be extended up to about a factor of 10 longer than that of a combustion chamber without any effects.
       
  • Liquid hydrogen tests of a sub-scale launcher upper stage feed line
           evaporation cooler
    • Abstract: Publication date: May 2019Source: Acta Astronautica, Volume 158Author(s): Armin Isselhorst, Dmitry Suslov, Jörg Riccius Propellant conditioning is a challenge for the development of cryogenic upper stages with re-ignitable main-engines. The VINCI engine needs for its operation propellant under specific conditions w.r.t. pressure and temperature to avoid cavitation inside the propellant pumps. After long ballistic phases the temperature of the propellant can increase to the respective saturation temperature of the tank pressure due to radiative solar heating. By means of the proposed feed line evaporation cooler 1stly the usual release of the tank pressure for thermally conditioning the propellant and 2ndly the follow-on re-pressurization of the tank with Helium can be avoided. Furthermore, this feedline evaporation cooler allows cooling only the propellant amount that is actually consumed by the engine. In this paper the design of the EC test unit, the LH2 test bench and respective results of the tests performed with LH2 will be presented in order to demonstrate the technology's capability and readiness. Additionally, a possible design and assembly on the A6 upper stage propulsion module is suggested.
       
  • XXI century tower: Laser orbital debris removal and collision avoidance
    • Abstract: Publication date: May 2019Source: Acta Astronautica, Volume 158Author(s): Max Calabro, Loïc Perrot A tall “tower” may have many useful applications in scientific domain: energy production, telecommunications, and entertainment. Sometimes space towers are proposed for an easier access to space such as the Thoth project culminating to an altitude of more than 20 km. Nevertheless, access to space is not the most promising use of a high-altitude tower, among them is the orbital debris removal, major point to keep a safe access to space. Ground based laser has been studied several times, laser on-board of a satellite also (chaser), but never a laser at the top of a tower.Such a solution may combine the advantages of the ground based system (i.e. maintenance, power supply, vast number of debris sightings, versatility) and of the space based system. Nevertheless, building a tall tower is a huge investment and must be profitable, but multiple applications of this tower may be envisaged such to have a good return of investment and so, the others potential utilisation may generate a bulk of revenues. As a driver, this tower supporting a powerful laser can be assimilated to a weapon and so must be kept under international control on the European territory.
       
  • On ground validation of debris removal technologies
    • Abstract: Publication date: May 2019Source: Acta Astronautica, Volume 158Author(s): P. Colmenarejo, M. Graziano, G. Novelli, D. Mora, P. Serra, A. Tomassini, K. Seweryn, G. Prisco, J. Gil Fernandez The goal of the activity On-ground Validation of Debris Removal Technologies, ORCO, has been to investigate and mature the complex couplings between the different control systems (GNC including image processing and robotics) for autonomous rigid capture between an active chaser vehicle and a cooperative/non-cooperative target, and derive the required algorithms and perform a HW-in-the-loop end-to-end demonstration. The prototyped solution is tested in the most realistic conditions obtainable on ground, including also the dynamics of the system as well as the relative visual based navigation system. The on-ground validation and integration is performed taking advantage of the GMV platform-art© dynamic test facility located in Madrid, Spain, with the addition of the hardware provided by the partners: robotic system from CBK (Poland) and visual system from TSD (Italy).
       
  • Contact dynamic models of space debris capturing using a net
    • Abstract: Publication date: May 2019Source: Acta Astronautica, Volume 158Author(s): Minghe Shan, Jian Guo, Eberhard Gill Contact dynamic models for active debris capturing using a net are presented and analyzed using numerical simulations. The contact dynamics are based on two methods: the penalty-based method and the impulse-based method. Both methods apply contact detection algorithms based on the Axis-Aligned Bounding Box. The impulse-based method is, for the first time, being used in a net capturing scenario. Strengths and weaknesses of both models are compared and discussed. Moreover, the results from numerical simulations of target capturing are presented and analyzed to evaluate the effectiveness of the contact dynamic models. It is found that the average difference of bullet trajectories obtained by two models can be restricted within 6% when it compares with the dimension of the net.
       
  • SRM plume: A candidate as space debris braking system for Just-In-Time
           Collision avoidance maneuver
    • Abstract: Publication date: May 2019Source: Acta Astronautica, Volume 158Author(s): A. Jarry, C. Bonnal, C. Dupont, S. Missonnier, L. Lequette, F. Masson A possible system suited for Just-In Time Collision Avoidance (JCA) is a cloud injected in a sub-orbital trajectory by a sounding rocket that will drag down the passing object because of the local higher density. The sudden deceleration experienced by the debris will after a few revolutions ensure a consistent deviation from its nominal trajectory and therefore will permit a safe reduction of any collision risk with other objects. This article first introduces a feasibility study of such a system, using as baseline an SRM and then enlarges the study to an enhanced system.
       
  • SPOOK - A comprehensive Space Surveillance and Tracking analysis tool
    • Abstract: Publication date: May 2019Source: Acta Astronautica, Volume 158Author(s): Oscar Rodriguez Fernandez, Jens Utzmann, Urs Hugentobler Space Surveillance and Tracking (SST) is the ability to detect and predict the movement of space debris in orbit around the Earth. SPOOK (SPace Object Observations and Kalman filtering) is a versatile and highly configurable software tool developed by Airbus, for the detection, cataloguing and orbit prediction analysis of Earth orbiting objects. It provides an integrated framework for all the activities related with SST sensor architecture simulation. Throughout this paper, the functionalities of the tool are described and examples of different simulation scenarios are provided.
       
  • Examination of spacecraft anomalies provides insight into complex space
           environment
    • Abstract: Publication date: May 2019Source: Acta Astronautica, Volume 158Author(s): Darren McKnight Spacecraft operations are affected by a variety of natural and manmade features that create significant ambiguity as to root cause determination for many anomalies and failures of satellites. The natural space environment comprises dynamic radiation, energetic atomic particles, and particulates (micrometeoroids and orbital debris) that vary temporally and spatially across relevant Earth orbits. Some of the failure mechanisms are further obfuscated by intricate local interactions, the fact that failures are often the result of more than one environmental effect, and lack of diagnostic sensors onboard spacecraft. At the same time, manmade influences on spacecraft anomalies and failures include design, manufacture, integration/installation, parts quality, testing completeness, and operations. These manmade aspects of the anomaly/failure attribution process are equally daunting as much of the relevant information is either not collected or not widely distributed for a variety of reasons. This paper details these dimensions of the anomaly/failure attribution process and provides data from a variety of operational examples to illustrate quantitative and specific actions to enhance the anomaly/failure attribution process short-term and long-term.
       
  • Dynamical evolution of space debris in the vicinity of GNSS regions
    • Abstract: Publication date: May 2019Source: Acta Astronautica, Volume 158Author(s): E.D. Kuznetsov, E.A. Avvakumova Dynamical evolution of space debris in the vicinity of orbits of the global navigation satellite systems: GLONASS, GPS, BeiDou, and Galileo was studied for a time span of 240 years. Time intervals space debris objects reach the regions of motion of navigation satellites were estimated. Initial orbits of the objects were chosen in the GNSS orbit regions as well as 450–1100 km above with respect to nominal semi-major axes of the navigation orbits. The results depend significantly on the orbital plane position. The objects pass through the GNSS region due to long period oscillations of eccentricities and inclinations of orbits, which are caused by dependency of inclination on luni-solar resonances and radiation pressure.
       
  • Sensitivity analysis of launch activities in Low Earth Orbit
    • Abstract: Publication date: May 2019Source: Acta Astronautica, Volume 158Author(s): Gian Luigi Somma, Hugh G. Lewis, Camilla Colombo This work aims to investigate the response of the low Earth orbit environment to the change in number and distribution of new launches and to understand the effects of the size and post-mission lifetime of a large constellation of spacecraft. The analysis presented in this paper were carried out using MISSD, Model for Investigating control Strategies for Space Debris, a multi-shell, and multi-species source-sink statistical model able to simulate the injection, removal and interaction of six type of objects up to an altitude of 2000 km. The results suggest that multiple regions experience a sensible increment in the orbital density when slightly increasing the launch activity for the next 200 years. Recently, many private companies expressed their interest in putting large constellations of satellites at 1100–1300 km altitude. However, results show that the launch of just six additional spacecraft per year in this region increased the spatial density by an amount equal to the projection over 200 years of today's most crowded region. Results also show that the increase in the orbital population and collision risk caused by the presence of large constellations could be mitigated using a high level of post-mission disposal compliance, reliable deorbit mechanisms and reducing thepost-mission lifetime to 5 years.
       
  • Dimensional and scale analysis applied to the preliminary assessment of
           the environment criticality of large constellations in LEO
    • Abstract: Publication date: May 2019Source: Acta Astronautica, Volume 158Author(s): Luciano Anselmo, Carmen Pardini Several analytical expressions, based on reasonable simplifying assumptions, were developed for the assessment of the environment criticality of large constellations and huge numbers of small satellites in low Earth orbit. They can provide preliminary quantitative answers to difficult questions, with no need of complex models and computations. Moreover, a specific figure of merit was introduced for gauging the environment criticality of new large constellations: the collision rate percentage increase. Because several systems might be operated at the same time, an alert threshold of no more than 10% per single constellation seemed a wise suggestion. Finally, several quantitative examples and the associated results were presented and discussed.
       
  • Features of space solar power station control system
    • Abstract: Publication date: May 2019Source: Acta Astronautica, Volume 158Author(s): G.T. Yermoldina, B.T. Suimenbayev, V.K. Sysoev, Zh.B. Suimenbayeva The article is devoted to the creation of a control system for the orbital segment of a space solar power station and the main principles of its creation. The simulation of the functioning of a demonstrational space solar power station operating in an elliptical orbit with the energy transfer in low orbit sections has been conducted and a high-precision control of the spacecraft at low altitudes has been considered. The result of the performed studies is the computational confirmation of the capabilities of the measuring, calculation and orientation to provide the required accuracy of the spacecraft orientation for demonstrating the energy transfer from orbit to the receiver system. The obtained results give grounds for the construction of a demonstrational space solar power station in the low orbit.
       
  • New strategy to preliminary design space launch vehicle based on a
           dedicated MDO platform
    • Abstract: Publication date: May 2019Source: Acta Astronautica, Volume 158Author(s): C. Dupont, A. Tromba, S. Missonnier This paper presents the methodology and the optimization strategy applied by Bertin Technologies for over 10 years to perform space launch vehicle design and implemented by using the property software platform HADES V15.0. The problem formulation consists of finding the best launch vehicle concept i.e. the one minimizing launch cost while satisfying technical, mission and architecture constraints (payload mass on final orbit, number of stages, propulsive technologies …). The strategy is based on a Multidisciplinary Design Feasible (MDF) approach coupled with the use of Genetic Algorithms (GA) for global optimization, and Gradient-Based Algorithms for final tuning and results refining. The HADES V15.0 platform provides the associated software environment, integrating a number of technical and economic modules consistently interconnected within a system optimization loop. The main disciplines taken into account in the platform are related to the launcher's propulsion, structure, aerodynamics, trajectory optimization and costs. The use of an integrated platform for multi-objective and multi-disciplinary optimization enables an efficient process and quick optimization. This methodology is particularly well fitted to the design of a small space launch vehicle, allowing to take into account the multidisciplinary nature of such a complex system and to manage the inherent sensitivity for this kind of vehicle. This platform was used specifically to design Bertin Technologies' cost-effective expandable Space Launch Vehicle (SLV) for Microsatellites, ROXANE, and to design the space launch vehicle in the H2020 ALTAIR project.
       
  • Active slosh control and damping - Simulation and experiment
    • Abstract: Publication date: May 2019Source: Acta Astronautica, Volume 158Author(s): Martin Konopka, Francesco De Rose, Hans Strauch, Christina Jetzschmann, Nicolas Darkow, Jens Gerstmann Future reignitable cryogenic upper stages perform long ballistic coasting phases in earth orbit. During those coasting phases, the tanks are loaded with liquid propellants and propellant sloshing occurs due to external disturbances or attitude change maneuvers. The sloshing propellant motion induces reaction forces and torques acting on the space vehicle structure, e.g. rocket upper stages. To keep the upper stage at the desired target attitude, the guidance, navigation, and control (GNC) algorithm commands thruster firings to counter the fluid forces. At ArianeGroup (AG), the Final Phase Simulator FiPS aims at simulating the coupling between fluid mechanics, GNC, and rigid body dynamics. To validate the coupling of GNC with linear lateral water sloshing, on ground experiments at the German Aerospace Center's Hexapod sloshing facility were performed. It was demonstrated that the developed control algorithm is able to damp the linear lateral sloshing within 4 s. FiPS simulations of the open and closed loop sloshing experiments showed that the experimental forces are matched with an uncertainty of less then 5% for open loop phases. For closed-loop phases the simulations match the experimental damping intervals with an accuracy of better than 5% and the force amplitude with an accuracy of about 20%.
       
  • Beacon advertising in an IEEE 802.15.4e TSCH network for space launch
           vehicles
    • Abstract: Publication date: May 2019Source: Acta Astronautica, Volume 158Author(s): Ines Khoufi, Pascale Minet, Badr Rmili Which wireless technology is able to meet the requirements of space launch vehicles in terms of latency, throughput and robustness' The IEEE 802.15.4e amendment has been designed to meet such requirements. More specifically, the Time Slotted Channel Hopping (TSCH) mode has been designed for industrial automation, process control and equipment monitoring. In this paper, we focus on the time needed by a joining node to detect beacons advertising the TSCH network. An Enhanced beacon is a TSCH frame that contains information on synchronization, channel hopping and timeslot used in the advertised network. However, the advertising policy is left unspecified by the IEEE 802.15.4e standard and is under the responsibility of a layer upper than the MAC one. Since beacons are broadcast, they are lost in case of collisions.The main problem is how to avoid such collisions'In this paper, we propose a Deterministic Beacon Advertising Algorithm, called DBA. The goal of DBA is to ensure that beacons are transmitted on all frequencies used by the TSCH network, regularly and without collision. With DBA, the exact value for the maximum time for a joining node to detect a beacon can be computed easily. We use the NS3 Simulator to evaluate this time as well as the number of message losses, considering different network topologies (star or multihop). We compare the performance of DBA with that of two algorithms existing in the state of the art.
       
  • Multi-channel wireless sensor network for Heavy-Lift Launch Vehicles
    • Abstract: Publication date: May 2019Source: Acta Astronautica, Volume 158Author(s): Gerard Chalhoub, Marie-Caroline Deux, Badr Rmili, Michel Misson A typical new generation Heavy-Lift Launch Vehicle (HLV) has more than 600 sensors on board. More than 80% of these sensors are used for non-critical operational and technological data. This data is sent to the ground launching controllers allowing them to supervise, in real time or a posteriori, information concerning the state of the HLV and the progress of the launching operation. Sensors are traditionally connected to a concentrator entity using cables. The concentrator is a special node in charge of collecting data that is generated by sensors and transmit it to the ground controllers unit. The use of wireless technology to interconnect sensor nodes with the concentrator would allow an ease of deployment and a weight gain which will help achieve assembly time reduction and a gain in terms of generated power. Nevertheless, of-the-shelf wireless technologies cannot guarantee a wired equivalent reliability in terms of packet delivery ratio or end-to-end delay. Indeed, when transmitting over wireless communication links it is challenging to find a solution that avoids data loss especially in high data rate scenarios. This is essentially due to the nature of the wireless medium that is very sensitive to the surrounding environment and to the possible simultaneous multiple accesses to the medium by the different sensor nodes. In this paper, we propose a wireless solution based on the physical layer of IEEE 802.15.4 standard in the 2.4 GHz frequency band that enhances packet delivery ratio under an acceptable end-to-end delay threshold during all phases of the launching operation. The proposal is a multi-channel and multi-hop protocol that allows sensors that are deployed close to the interstage of the HLV to communicate with a multi-radio interface concentrator node. Simulation results show promising performance in terms of packet delivery rate and end-to-end delay.
       
  • On-board spacecraft relative pose estimation with high-order extended
           Kalman filter
    • Abstract: Publication date: May 2019Source: Acta Astronautica, Volume 158Author(s): Francesco Cavenago, Pierluigi Di Lizia, Mauro Massari, Alexander Wittig This paper analyzes the real-time relative pose estimation and attitude prediction of a tumbling target spacecraft through a high-order numerical extended Kalman filter based on differential algebra. Indeed, in the differential algebra framework, the Taylor expansion of the phase flow is automatically available once the spacecraft dynamics is integrated and thus the need to write and integrate high-order variational equations is completely avoided making the presented solution easier to implement. To validate the technique, the ESA's e.deorbit mission, involving the Envisat satellite, is used as reference test case. The developed algorithms are implemented on a BeagleBone Black platform, as representative of the limited computational capability available on onboard processors. The performance is assessed by varying the measurement acquisition frequency and processor clock frequency, and considering various levels of uncertainties. A comparison among the different orders of the filter is carried out.
       
  • Systematic performance-oriented guidance tuning for descent & landing on
           small planetary bodies
    • Abstract: Publication date: May 2019Source: Acta Astronautica, Volume 158Author(s): Pedro Simplício, Andrés Marcos, Eric Joffre, Mattia Zamaro, Nuno Silva Descent & landing (D&L) on small planetary bodies are scientifically rewarding exploration missions but they are technically challenging due to the complex and poorly-known environment around those bodies. The standard guidance synthesis approach considers nominal conditions and applies optimal control theory to obtain guidance law gains, followed by intensive verification and validation. In this article, it is shown that the standard approach may yield gains that are not optimal once dispersions (and/or other optimality metrics) are taken into account and a tuning approach is then proposed based on a priori methodological system assessment. The proposed approach employs systematic high-fidelity simulations to generate trade-off maps. These maps can be generated by on ground operators based on the best estimated conditions and uploaded to the spacecraft as it approaches the target. The proposed systematic guidance tuning and resulting maps also provide a valuable understanding of the system dynamics towards the application of other industry-oriented tools such as structured ℋ∞ optimisation. It is shown that the proposed tuning enables propellant consumption reductions of around 40% compared to state-of-practice gain selections.
       
  • Robust relative navigation for spacecraft rendezvous using differential
           drag
    • Abstract: Publication date: May 2019Source: Acta Astronautica, Volume 158Author(s): S. Chocron, D. Choukroun This work is concerned with the development of relative navigation filters processing relative position measurements of two satellites that perform rendezvous via differential drag only along low Earth orbits. The filters are developed in the Leader Hill frame with an emphasis on differential drag uncertainty modeling. Embedding the atmosphere density daily high variability in a bitopic uncertainty yields a novel robust H∞ filter of the six relative motion states. For comparison two Kalman filters matched to other atmosphere density models are developed. Furthermore the navigation are embedded in a realistic guidance navigation and attitude control and determination architecture (GNC/ADC) for nanosatellites. The proposed test case features two nanosatellites at 300 km altitude switching from positive to negative differential drag modes via 3D rigid body rotation. The 3D attitude control system involves three reactions wheels and three magnetorquers. The satellites inertial attitudes are estimated using three rate gyroscopes and coarse vector measurements. The proposed GNC/ADC scheme is tested in a high fidelity simulation environment. With 1 m relative position measurement accuracy and 10° attitude pointing accuracy the steady-state along track navigation errors are 4 m, 7 m, and 8 m (RMS) for the H∞ filter and the Kalman filters, respectively. The H∞ filter also shows quicker convergence and lesser sensitivity to the atmosphere density high variability. The two satellites succeed in closing an initial along track separation distance from 7500 m down to 250 m within 10 orbits, while the final radial deviation is about 10 m.
       
  • The control optimization of low-orbit spacecraft with electric ramjet
    • Abstract: Publication date: May 2019Source: Acta Astronautica, Volume 158Author(s): Alexander S. Filatyev, Olga V. Yanova The problem of optimal control by the thrust vector of the spacecraft with electric ramjet to change the orbital parameters is considered. Optimal control is determined by solving the problem on the conditional maximum of the local (at the current point) impact of the perturbing acceleration on the functional, assuming the perturbations' smallness compared to gravity. An approximate synthesis of the optimal thrust vector is obtained. The investigation results are given depending on the available capacity of the power source, parameters of the spacecraft with electric ramjet and initial orbit.
       
  • A three-step decomposition method for solving the minimum-fuel
           geostationary station keeping of satellites equipped with electric
           propulsion
    • Abstract: Publication date: May 2019Source: Acta Astronautica, Volume 158Author(s): Clément Gazzino, Denis Arzelier, Luca Cerri, Damiana Losa, Christophe Louembet, Christelle Pittet In this paper, a control scheme is elaborated in order to perform the station keeping of a geostationary satellite equipped with electric propulsion while minimizing the fuel consumption. The use of electric thrusters imposes to take into account some additional non linear and operational constraints that make the overall station keeping optimal control problem difficult to solve directly. That is why the station keeping problem is decomposed in three successive control problems. The first one consists in solving a classical optimal control problem with an indirect method initialized by a direct method without enforcing the thrusters operational constraints. Starting from this non feasible solution for the genuine problem, the thrusters operating constraints are incorporated in the second problem, whose solution produces a feasible but non optimal control profile via two different ways. Finally, the third optimizes the commutation times thanks to a method borrowed to the switched systems theory. Simulation results on a realistic example validate the benefit of this particular control scheme in the reduction of the fuel consumption for the geostationary station keeping problem.
       
  • Formation flying along unstable Libration Point Orbits using switching
           Hamiltonian structure-preserving control
    • Abstract: Publication date: May 2019Source: Acta Astronautica, Volume 158Author(s): Seungyun Jung, Youdan Kim Orbits for spacecraft formation flight along an unstable orbit are designed. The Hamiltonian structure-preserving (HSP) control is used to stabilize the motion of the spacecraft. Using a simple switching control strategy, the size of a circular orbit relative to a nominal trajectory can be systematically designed. To perform station-keeping of a spacecraft, the proposed HSP control is repeatedly applied. The nonlinear stability of the controller is also analyzed using Lagrange-Dirichlet criterion. To demonstrate the performance of the proposed switching HSP controller, a numerical simulation is performed for the formation flight of the spacecraft in Earth-Moon system's L2 halo orbit.
       
  • IFC - Publication Information
    • Abstract: Publication date: May 2019Source: Acta Astronautica, Volume 158Author(s):
       
  • Effect of tangential swirl air inlet angle on the combustion efficiency of
           a hybrid powder-solid ramjet
    • Abstract: Publication date: Available online 19 March 2019Source: Acta AstronauticaAuthor(s): Yihua Xu, Rui Jia, Humberto Medina, Haijun Sun A new ramjet configuration using powder and solid fuel as propellant is investigated, namely, hybrid powder-solid ramjet (HPSR). Boron particles were used as the powder in this study. In order to improve combustion efficiency of boron and simplify the engine structure, a tangential swirl air inlet is adopted on the HPSR. Ignition model based on the multi-layer oxide structure and Global reaction combustion model of boron particles, the Lagrangian particle trajectory model and the realizable k-ε turbulence model were implemented to calculate three-dimensional two-phase flow and combustion in the HPSR with the different tangential air inlet angles (0°,5°, 10°, 15°, 20°, 25°). The effects of tangential air inlet angles on the ignition and combustion of boron were analyzed. The results show that when the tangential swirl air inlet angle is 10°, the combustion efficiency of boron particles and the total combustion efficiency of engine are the highest; the temperature distribution in the second combustion chamber is uniform, and the ignition distance of particles is small, for the HPSR configuration tested.
       
  • HMGB1 mediated autophagy protects glioblastoma cells from carbon-ion beam
           irradiation injury
    • Abstract: Publication date: Available online 19 March 2019Source: Acta AstronauticaAuthor(s): Runhong Lei, Liben Yan, Yulin Deng, Jin Xu, Tuo Zhao, M. Umer Farooq Awan, Qiang Li, Guangming Zhou, Xiao Wang, Hong Ma The present study investigated autophagy changes and the expression of HMGB1 in human glioblastoma cells, responding to carbon-ion beam irradiation (35 keV/μm, 80.55 MeV/u). U251 cells were irradiated with carbon-ion beams and cell proliferation was measured by counting the number of living cells. The expression of Light Chain 3 beta (LC3B), Beclin 1, high-mobility-group box 1 (HMGB1), pro-form caspase-3 and Cellular FLICE-like inhibitory protein (c-FLIP) was analyzed by western blotting. Caspase enzyme activity was determined via a caspase cleavage based florescent substrate commercial Kit. Living cell counting demonstrated a time- and dose-dependent cell death in U251 cells. The expression of LC3B and Beclin 1 revealed that, a high level of autophagy was induced 24 h after irradiation with 1 Gy carbon ions and then decreased in a time- and dose-dependent manner. The expression of the whole HMGB1 showed a well correlation with the dynamic autophagic level. Cytoplasmic HMGB1 maintained autophagy was concluded. Enzyme-Linked Immuno Sorbent Assay (ELISA) measurement found that, HMGB1 was released into the extracellular space in a time- and dose-dependent manner. Lower intracellular HMGB1 levels correlated with decreased autophagy as measured by the expression of LC3B. Decreased expression of pro-form caspase-3 and c-FLIP as well as the increased caspase enzyme activity indicated that apoptosis was induced by carbon-ion beam irradiation. Inhibition of HMGB1 release from the area of intracellular to that of extracellular significantly increased cell survival. In summary, carbon-ion beam irradiation could elevate autophagy and HMGB1 expression efficiently, which would protect the cells from programmed cell death via inducing autophagy. Apoptosis as measured by expression of caspase activities increased as the dose increased, which was accompanied with decreased levels of LC3B and HMGB1.
       
  • Including analytically reduced chemistry (ARC) in CFD applications
    • Abstract: Publication date: Available online 13 March 2019Source: Acta AstronauticaAuthor(s): Anne Felden, Perrine Pepiot, Lucas Esclapez, Eleonore Riber, Bénédicte Cuenot Reacting numerical simulations today are often based on either fitted global reaction schemes, comprised of a few empirical reactions, or pre-tabulated laminar flame solutions computed with detailed chemistry. Although both methods can accurately predict global quantities such as laminar flame speed and burnt gas composition, they have significant limitations. In particular, neither are able to directly and adequately describe the complexity of pollutant chemistry. In the context of reducing harmful emissions of the next generation of aeronautical combustors, however, including these needed additional kinetic details in combustion simulations is becoming essential. Direct integration of detailed chemistry in accurate turbulent combustion models is not a viable option in the foreseeable future, because of excessive computational demands and numerical stiffness. In this context, Analytically Reduced Chemistry (ARC) represents an attractive compromise between accuracy and efficiency, and is already employed in relatively complex Direct Numerical Simulations (DNS) and Large Eddy Simulations (LES). ARCs are knowledge-based compact mechanisms retaining only the most relevant kinetic information as extracted directly, and without fitting, from detailed chemical models using specialized reduction techniques (important species identification through graph search, lumping of species with similar features, short-living species identification, etc.). In recent years, several multi-step efficient and automated reduction tools have been developed, enabling the easy generation of ARCs with minimum input and knowledge from the user. The main objective of this paper is to present a review of ARCs for fuels ranging from methane to aviation kerosene surrogates, recently derived with such a multi-step automated reduction tool: YARC. Information about the applicability and range of validity of each derived mechanism are given, along with further references. Each one was specifically derived to be convenient to use in CFD; in particular, the stiffness was regarded as a key factor and the final number of transported species never exceeds thirty. In a final section, the great potential of the methodology is illustrated in a multi-phase, reactive LES application where the fuel is a real multi-component transportation fuel. To that end, an ARC based on a Jet A described by the novel Hybrid Chemistry (HyChem) approach is coupled with the Dynamically Thickened Flame LES (DTFLES) model and directly integrated into the LES solver AVBP. A Lagrangian spray description is used. Results are compared to experimental data in terms of temperature and major species (CO2, H2O, CO, NO) mass fractions, leading to very satisfying results.
       
  • Aluminium droplets combustion and SRM instabilities
    • Abstract: Publication date: Available online 12 March 2019Source: Acta AstronauticaAuthor(s): Olivier Orlandi, Mathieu Plaud, Franck Godfroy, Severine Larrieu, Nathalie Cesco This paper presents the effects of the combustion of aluminium droplets in the context of solid propulsion. A focus is made on the specific case of pressure oscillations. After a brief presentation of the characteristics of aluminium combustion, interaction with the acoustics of the motor is introduced. The unsteady phenomenon referred to as ‘ITHAC’ is studied through the analysis of the “Stelis Calypso” test firing. The results show that aluminium combustion is the driving mechanism that leads to a strong instability of several bars. This analysis is supported by numerous two-phase flow simulations that prove the role of aluminium droplets in the triggering of instability characterised by high pressure oscillation levels. A second instability is also addressed. Solid rocket motors are subject to surface vortex shedding (SVS) for which pressure oscillation levels can drastically be modified by aluminium droplets combustion. Depending on the motor geometry and particles size, combustion increases or dampens the hydrodynamic instability and can be considered as an explanation to the pressure oscillations observed during tests of aluminised propellants.
       
  • Microwave resonator method for measuring transient mass gasification rate
           of condensed systems
    • Abstract: Publication date: Available online 12 March 2019Source: Acta AstronauticaAuthor(s): V. Zarko, V. Perov, A. Kiskin, D. Nalivaichenko The paper presents preliminary results on developing new contactless method for measuring transient mass gasification rate of condensed systems. The method is based on recording the forward power gain coefficient of microwave signal induced by the variation of tested material mass in the microwave gage of a resonator type. The gage design provides measurements of the gasification rate of a bored sample in conditions of intense gas blowing through. According to estimations the temporal resolution of the gage is not less than 1 ms and calculated spatial resolution comprises about few microns for the sample with outer diameter of 17 mm and bore diameter of 10 mm.
       
  • Numerical Simulation of Turbulent Boundary Layers with Foreign Gas
           Transpiration using OpenFOAM
    • Abstract: Publication date: Available online 12 March 2019Source: Acta AstronauticaAuthor(s): Daniel Prokein, Jens von Wolfersdorf Transpiration cooling in combination with porous high-temperature materials is a promising technique for thermal protection of highly-loaded aerospace applications. In this study, we present a modified OpenFOAM solver which is applied to the simulation of a turbulent channel flow with boundary layer blowing. Different models for porous wall injection of air, argon, and helium into a main flow of air are proposed and evaluated. Subsequently, same and foreign gas transpiration is simulated for cold and heated main flow conditions and the results are compared to experimental data and correlations from literature. A very good overall agreement is found for velocity and temperature boundary layer profiles as well as the dimensionless parameters for wall shear stress and heat transfer.
       
  • Development of catalytic materials for decomposition of ADN-based
           monopropellants
    • Abstract: Publication date: Available online 12 March 2019Source: Acta AstronauticaAuthor(s): Corentin Maleix, Pierre Chabernaud, Rachid Brahmi, Romain Beauchet, Yann Batonneau, Charles Kappenstein, Martin Schwentenwein, Robert-Jan Koopmans, Sebastian Schuh, Carsten Scharlemann Hydrazine (N2H4), one of the widest used liquid monopropellant is to be replaced by “greener” propellants based on ammonium dinitramide (ADN, NH4+N(NO2)2-), such as LMP-103S and FLP-106 within the framework of the Horizon 2020 Rheform project. While hydrazine can rely on a catalytic technology based on conventional materials such as γ-Al2O3 (due to the adiabatic decomposition temperature of about 900–1000 °C), LMP-103S and FLP-106 require catalyst support materials that can withstand higher temperatures (about 1650 °C and 1900 °C, respectively) and exhibit a sufficient porosity and resistance to sintering. On these terms, among the various candidates for catalyst support, monolith-shaped supports were investigated.
       
  • A model for solid propellant burning fluctuations using mesoscale
           simulations
    • Abstract: Publication date: Available online 12 March 2019Source: Acta AstronauticaAuthor(s): Stany Gallier, Mathieu Plaud The combustion of composite solid propellants shows velocity fluctuations which are expected to have marked effects on turbulence or aeroacoustic instabilities. In this work, we propose a specific propellant boundary condition that models such fluctuations using a spectral synthetic turbulence approach. In order to feed this model with reliable input data, we consider mesoscale direct simulations of propellant combustion. This new propellant boundary condition is implemented in a CFD flow solver and applied to a real lab-scale motor. Simulations show that burning fluctuations can trigger aeroacoustic instabilities, in better agreement with experiments.
       
  • Smoke oxide particles formation at the burning surface of condensed
           systems
    • Abstract: Publication date: Available online 12 March 2019Source: Acta AstronauticaAuthor(s): Valery A. Babuk, Nikita L. Budnyi Main positions of the mathematical model of smoke oxide particles (SOPs) formation at the burning surface of condensed system are developed. The model includes description of SOPs formation during burning of non-agglomerating metal in gas phase near surface of the burning condensed system, and during burning of metal of agglomerating particles on the surface of skeleton layer. Results and perspectives of using the model are considered for two different condensed systems (based on active binder and based on ammonium nitrate), which produce SOPs mostly during the development of one of the mentioned mechanisms. A comparison of numerical and experimental results has allowed to make a conclusion about their satisfactory agreement. An analysis of the model allows to create a base for its future improvement and application.
       
  • Radio frequency attenuation by a rocket plume using diffraction theory and
           finite element modeling
    • Abstract: Publication date: Available online 12 March 2019Source: Acta AstronauticaAuthor(s): Éva Dieudonné, Abelin Kameni, Lionel Pichon, David Monchaux Radio frequency communication between the space launcher and the mission control are unusually disturbed by the exhaust plume present in rocket engines. This paper presents the computation of radio wave propagation through the exhaust plume. Thus, frequency-domain finite element method and time-domain discontinuous Galerkin method are implemented for computations in case of a ground domain experiment. Numerical results compared to those obtained from ground experiment show good approximation of the propagation through the plasma over a wide frequency band. For the launcher in flight, an asymptotic method is proposed and has the advantage to give a fast evaluation of the scattering solution. In this case, the exhaust plume area is considered as a perfectly conducting trapezium whose parameters are extracted from the distribution of the plasma permittivity. Results related to the asymptotic method appear to be in good agreement with results based on the full wave approaches.
       
  • Formation of solid residues in combustion of boron-containing solid
           propellants
    • Abstract: Publication date: Available online 12 March 2019Source: Acta AstronauticaAuthor(s): Sergey A. Rashkovskiy Boron-containing solid propellants are promising propellants for ducted rockets. The experimental data show that combustion of boron-containing propellants is accompanied by an intense conglomeration of the boron particles near the burning surface. As a result, the boron particles conglomerates which are the branched coral structures composed of sintered boron particles are formed in combustion of boron-containing solid propellants. This results in decrease in combustion efficiency of ducted rockets. To calculate the ignition and combustion of a conglomerate in the secondary combustor of a ducted rocket, it is necessary to know the size, structure and shape of the boron particle conglomerates that can significantly affect these processes. In this paper, we consider a model and a method for calculating the boron particles conglomeration in combustion of the boron-containing solid propellants. The process of the boron particles conglomeration is considered as a result of competition between two main processes: the formation of adhesive bonds between the contacting boron particles and rupture of these bonds under the action of the aerodynamic detached force from the side the flow of gaseous combustion products of solid propellant. The criterion of formation of residues (slag) on the burning surface of boron-containing propellants is considered. It is shown that depending on the propellant burning rate law, two different types of propellants with different conglomeration behavior can exist. The results of calculations of the boron particles conglomeration which demonstrate the slag formation are shown.
       
 
 
JournalTOCs
School of Mathematical and Computer Sciences
Heriot-Watt University
Edinburgh, EH14 4AS, UK
Email: journaltocs@hw.ac.uk
Tel: +00 44 (0)131 4513762
Fax: +00 44 (0)131 4513327
 
Home (Search)
Subjects A-Z
Publishers A-Z
Customise
APIs
Your IP address: 34.229.97.16
 
About JournalTOCs
API
Help
News (blog, publications)
JournalTOCs on Twitter   JournalTOCs on Facebook

JournalTOCs © 2009-