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 Subjects -> MATHEMATICS (Total: 867 journals)     - APPLIED MATHEMATICS (69 journals)    - GEOMETRY AND TOPOLOGY (19 journals)    - MATHEMATICS (645 journals)    - MATHEMATICS (GENERAL) (40 journals)    - NUMERICAL ANALYSIS (19 journals)    - PROBABILITIES AND MATH STATISTICS (75 journals) MATHEMATICS (645 journals)                  1 2 3 4 | Last
 Showing 1 - 200 of 538 Journals sorted alphabetically Abakós       (Followers: 3) Abhandlungen aus dem Mathematischen Seminar der Universitat Hamburg       (Followers: 2) Academic Voices : A Multidisciplinary Journal       (Followers: 2) Accounting Perspectives       (Followers: 6) ACM Transactions on Algorithms (TALG)       (Followers: 16) ACM Transactions on Computational Logic (TOCL)       (Followers: 4) ACM Transactions on Mathematical Software (TOMS)       (Followers: 6) ACS Applied Materials & Interfaces       (Followers: 21) Acta Applicandae Mathematicae       (Followers: 1) Acta Mathematica       (Followers: 10) Acta Mathematica Hungarica       (Followers: 2) Acta Mathematica Scientia       (Followers: 5) Acta Mathematica Sinica, English Series       (Followers: 5) Acta Mathematica Vietnamica Acta Mathematicae Applicatae Sinica, English Series Advanced Science Letters       (Followers: 5) Advances in Applied Clifford Algebras       (Followers: 3) Advances in Calculus of Variations       (Followers: 2) Advances in Catalysis       (Followers: 5) Advances in Complex Systems       (Followers: 7) Advances in Computational Mathematics       (Followers: 15) Advances in Decision Sciences       (Followers: 4) Advances in Difference Equations       (Followers: 1) Advances in Fixed Point Theory       (Followers: 5) Advances in Geosciences (ADGEO)       (Followers: 9) Advances in Linear Algebra & Matrix Theory       (Followers: 1) Advances in Materials Sciences       (Followers: 16) Advances in Mathematical Physics       (Followers: 6) Advances in Mathematics       (Followers: 10) Advances in Numerical Analysis       (Followers: 4) Advances in Operations Research       (Followers: 11) Advances in Porous Media       (Followers: 4) Advances in Pure and Applied Mathematics       (Followers: 5) Advances in Pure Mathematics       (Followers: 4) Advances in Science and Research (ASR)       (Followers: 6) Aequationes Mathematicae       (Followers: 2) African Journal of Educational Studies in Mathematics and Sciences       (Followers: 5) African Journal of Mathematics and Computer Science Research       (Followers: 4) Afrika Matematika       (Followers: 1) Air, Soil & Water Research       (Followers: 7) AKSIOMA Journal of Mathematics Education       (Followers: 1) Algebra and Logic       (Followers: 2) Algebra Colloquium       (Followers: 4) Algebra Universalis       (Followers: 2) Algorithmic Operations Research       (Followers: 5) Algorithms       (Followers: 9) Algorithms Research       (Followers: 1) American Journal of Biostatistics       (Followers: 9) American Journal of Computational and Applied Mathematics       (Followers: 3) American Journal of Mathematical Analysis American Journal of Mathematics       (Followers: 7) American Journal of Operations Research       (Followers: 5) American Mathematical Monthly       (Followers: 6) An International Journal of Optimization and Control: Theories & Applications       (Followers: 7) Analele Universitatii Ovidius Constanta - Seria Matematica       (Followers: 1) Analysis       (Followers: 2) Analysis and Applications       (Followers: 1) Analysis and Mathematical Physics       (Followers: 4) Analysis Mathematica Annales Mathematicae Silesianae Annales mathématiques du Québec       (Followers: 4) Annales UMCS, Mathematica       (Followers: 1) Annales Universitatis Paedagogicae Cracoviensis. 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 CEAS Space Journal   [SJR: 0.221]   [H-I: 5]   [0 followers]  Follow         Hybrid journal (It can contain Open Access articles)    ISSN (Print) 1868-2510 - ISSN (Online) 1868-2502    Published by Springer-Verlag  [2329 journals]
• Design, integration and preliminary results of the IXV Catalysis
experiment
• Authors: Alan Viladegut; F. Panerai; O. Chazot; T. Pichon; P. Bertrand; C. Verdy; C. Coddet
Pages: 141 - 151
Abstract: The CATalytic Experiment (CATE) is an in-flight demonstration of catalysis effects at the surface of thermal protection materials. A high-catalytic coating was applied over the baseline ceramic material on the windward side of the intermediate experimental vehicle (IXV). The temperature jump due to different catalytic activities was detected during re-entry through measurements made with near-surface thermocouples on the windward side of the vehicle. The experiment aimed at contributing to the development and validation of gas/surface interaction models for re-entry applications. The present paper summarizes the design of CATE and its integration on the windward side of the IXV. Results of a qualification campaign at the Plasmatron facility of the von Karman Institute for Fluid Dynamics are presented. They provided an experimental evidence of the temperature jump at the low-to-high catalytic interface of the heat shield under aerothermal conditions relevant to the actual IXV flight. These tests also gave confidence so that the high-catalytic patch would not endanger the integrity of the vehicle and the safety of the mission. A preliminary assessment of flight data from the thermocouple measurements shows consistency with results of the qualification tests.
PubDate: 2017-06-01
DOI: 10.1007/s12567-016-0136-2
Issue No: Vol. 9, No. 2 (2017)

• Laser optics in space failure risk due to laser induced contamination
• Authors: D. Kokkinos; H. Schroeder; K. Fleury-Frenette; M. P. Georges; W. Riede; G. Tzeremes; P. Rochus
Pages: 153 - 162
Abstract: In this paper, a study of the evolution and morphology of UV laser-induced contamination (LIC) on optical surfaces due to hydrocarbons will be presented. LIC is a major hazard for lasers that operate in vacuum conditions. Recent studies have shown that the manufacturing method and cleaning of optical components can significantly mitigate LIC growth but never stop it completely. To better understand and model the evolution of LIC the deposition rate and transmission decay were observed via a CCD camera that measured laser induced fluorescence (LIF) and energy detectors, respectively. The affected sites were observed using Atomic Force Microscopy (AFM) and Phase Shift Interferometry (PSI). The LIC affected area diameters obtained by different experimental conditions were then compared with the theoretical prediction derived by the model. Very good agreement between this empirical model and the experimental results was found for the relevant parameter regimes under investigation. A novel methodology to determine the possibility of permanent optical damage due to LIC produced thermal effects is also discussed.
PubDate: 2017-06-01
DOI: 10.1007/s12567-016-0137-1
Issue No: Vol. 9, No. 2 (2017)

• Survey on the implementation and reliability of CubeSat electrical bus
interfaces
• Authors: Jasper Bouwmeester; Martin Langer; Eberhard Gill
Pages: 163 - 173
Abstract: This paper provides results and conclusions on a survey on the implementation and reliability aspects of CubeSat bus interfaces, with an emphasis on the data bus and power distribution. It provides recommendations for a future CubeSat bus standard. The survey is based on a literature study and a questionnaire representing 60 launched CubeSats and 44 to be launched CubeSats. It is found that the bus interfaces are not the main driver for mission failures. However, it is concluded that the Inter Integrated Circuit (I2C) data bus, as implemented in a great majority of the CubeSats, caused some catastrophic satellite failures and a vast amount of bus lockups. The power distribution may lead to catastrophic failures if the power lines are not protected against overcurrent. A connector and wiring standard widely implemented in CubeSats is based on the PC/104 standard. Most participants find the 104 pin connector of this standard too large. For a future CubeSat bus interface standard, it is recommended to implement a reliable data bus, a power distribution with overcurrent protection and a wiring harness with smaller connectors compared with PC/104.
PubDate: 2017-06-01
DOI: 10.1007/s12567-016-0138-0
Issue No: Vol. 9, No. 2 (2017)

• The TICTOP nozzle: a new nozzle contouring concept
• Authors: Manuel Frey; Konrad Makowka; Thomas Aichner
Pages: 175 - 181
Abstract: Currently, mainly two types of nozzle contouring methods are applied in space propulsion: the truncated ideal contour (TIC) and the thrust-optimized parabola (TOP). This article presents a new nozzle contouring method called TICTOP, combining elements of TIC and TOP design. The resulting nozzle is shock-free as the TIC and therefore does not induce restricted shock separation leading to excessive side-loads. Simultaneously, the TICTOP nozzle will allow higher nozzle wall exit pressures and hence give a better separation margin than is the case for a TIC. Hence, this new nozzle type combines the good properties of TIC and TOP nozzles and eliminates their drawbacks. It is especially suited for first stage application in launchers where flow separation and side-loads are design drivers.
PubDate: 2017-06-01
DOI: 10.1007/s12567-016-0139-z
Issue No: Vol. 9, No. 2 (2017)

• The TUBIN nanosatellite mission for wildfire detection in thermal infrared
• Authors: Merlin F. Barschke; Julian Bartholomäus; Karsten Gordon; Marc Lehmann; Klaus Brieß
Pages: 183 - 194
Abstract: The increasing number of wildfires has significant impact on the Earth’s climate system. Furthermore, they cause severe economic damage in many parts of the world. While different land and airborne wildfire detection and observation systems are in use in some areas of the world already, spaceborne systems offer great potential regarding global and continuous observation. TUBIN is a proof-of-concept mission to demonstrate the capabilities of a nanosatellite carrying lightweight infrared microbolometer arrays for spaceborne detection of wildfires and other high-temperature events. To this end, TUBIN carries two infrared microbolometers complemented by a CMOS imager. The TUBIN space segment is based on the TUBiX20 nanosatellite platform of Technische Universität Berlin and is the first mission that implements the full-scale attitude determination and control system of TUBiX20. Thereby, the TUBIN mission will demonstrate the platform’s ability to support a challenging Earth observation mission.
PubDate: 2017-06-01
DOI: 10.1007/s12567-016-0140-6
Issue No: Vol. 9, No. 2 (2017)

• A critical review of nanotechnologies for composite aerospace structures
• Authors: Vassilis Kostopoulos; Athanasios Masouras; Athanasios Baltopoulos; Antonios Vavouliotis; George Sotiriadis; Laurent Pambaguian
Pages: 35 - 57
Abstract: The past decade extensive efforts have been invested in understanding the nano-scale and revealing the capabilities offered by nanotechnology products to structural materials. Integration of nano-particles into fiber composites concludes to multi-scale reinforced composites and has opened a new wide range of multi-functional materials in industry. In this direction, a variety of carbon based nano-fillers has been proposed and employed, individually or in combination in hybrid forms, to approach the desired performance. Nevertheless, a major issue faced lately more seriously due to the interest of industry is on how to incorporate these nano-species into the final composite structure through existing manufacturing processes and infrastructure. This interest originates from several industrial applications needs that request the development of new multi-functional materials which combine enhanced mechanical, electrical and thermal properties. In this work, an attempt is performed to review the most representative processes and related performances reported in literature and the experience obtained on nano-enabling technologies of fiber composite materials. This review focuses on the two main composite manufacturing technologies used by the aerospace industry; Prepreg/Autoclave and Resin Transfer technologies. It addresses several approaches for nano-enabling of composites for these two routes and reports latest achieved results focusing on performance of nano-enabled fiber reinforced composites extracted from literature. Finally, this review work identifies the gap between available nano-technology integration routes and the established industrial composite manufacturing techniques and the challenges to increase the Technology Readiness Level to reach the demands for aerospace industry applications.
PubDate: 2017-03-01
DOI: 10.1007/s12567-016-0123-7
Issue No: Vol. 9, No. 1 (2017)

• Influence of hydrogen temperature on the stability of a rocket engine
combustor operated with hydrogen and oxygen
• Authors: Stefan Gröning; Justin Hardi; Dmitry Suslov; Michael Oschwald
Pages: 59 - 76
Abstract: Since the late 1960s, low hydrogen injection temperature is known to have a destabilising effect on rocket engines with the propellant combination hydrogen/oxygen. Self-excited combustion instabilities of the first tangential mode have been found recently in a research rocket combustor operated with the propellant combination hydrogen/oxygen with a hydrogen temperature of 95 K. A hydrogen temperature ramping experiment has been performed with this research combustor to analyse the impact of hydrogen temperature on the self-excited combustion instabilities. The temperature was varied between 40 and 135 K. Contrary to past results found in literature, the combustor was found to be stable at low hydrogen temperatures while increased oscillation amplitudes of the first tangential mode were found at higher temperatures of around 100 K and above, which is consistent with previous observations of instabilities in this combustor. Further analysis shows that hydrogen temperature has a strong impact on the combustion chamber resonance frequencies. By varying the hydrogen injection temperature, the frequency of the first tangential mode is shifted to coincide with the second longitudinal resonance frequency of the liquid oxygen injector. Excitation of combustion chamber pressure oscillations was observed during such events.
PubDate: 2017-03-01
DOI: 10.1007/s12567-016-0130-8
Issue No: Vol. 9, No. 1 (2017)

• Beacons for supporting lunar landing navigation
• Authors: Stephan Theil; Leonardo Bora
Pages: 77 - 95
Abstract: Current and future planetary exploration missions involve a landing on the target celestial body. Almost all of these landing missions are currently relying on a combination of inertial and optical sensor measurements to determine the current flight state with respect to the target body and the desired landing site. As soon as an infrastructure at the landing site exists, the requirements as well as conditions change for vehicles landing close to this existing infrastructure. This paper investigates the options for ground-based infrastructure supporting the onboard navigation system and analyzes the impact on the achievable navigation accuracy. For that purpose, the paper starts with an existing navigation architecture based on optical navigation and extends it with measurements to support navigation with ground infrastructure. A scenario of lunar landing is simulated and the provided functions of the ground infrastructure as well as the location with respect to the landing site are evaluated. The results are analyzed and discussed.
PubDate: 2017-03-01
DOI: 10.1007/s12567-016-0132-6
Issue No: Vol. 9, No. 1 (2017)

• Green micro-resistojet research at Delft University of Technology: new
options for Cubesat propulsion
• Authors: A. Cervone; B. Zandbergen; D. C. Guerrieri; M. De Athayde Costa e Silva; I. Krusharev; H. van Zeijl
Pages: 111 - 125
Abstract: The aerospace industry is recently expressing a growing interest in green, safe and non-toxic propellants for the propulsion systems of the new generation of space vehicles, which is especially true in the case of Cubesat micro-propulsion systems. Demanding requirements are associated to the future missions and challenges offered by this class of spacecraft, where the availability of a propulsion system might open new possibilities for a wide range of applications including orbital maintenance and transfer, formation flying and attitude control. To accomplish these requirements, Delft University of Technology is currently developing two different concepts of water-propelled micro-thrusters based on MEMS technologies: a free molecular micro-resistojet operating with sublimating solid water (ice) at low plenum gas pressure of less than 600 Pa, and a more conventional micro-resistojet operating with liquid water heated and vaporized by means of a custom designed silicon heating chamber. In this status review paper, the current design and future expected developments of the two micro-propulsion concepts is presented and discussed, together with an initial analysis of the expected performance and potential operational issues. Results of numerical simulations conducted to optimize the design of the heating and expansion slots, as well as a detailed description of the manufacturing steps for the conventional micro-resistojet concept, are presented. Some intended steps for future research activities, including options for thrust intensity and direction control, are briefly introduced.
PubDate: 2017-03-01
DOI: 10.1007/s12567-016-0135-3
Issue No: Vol. 9, No. 1 (2017)

• HEOSAT: a mean elements orbit propagator program for highly elliptical
orbits
• Authors: Martin Lara; Juan F. San-Juan; Denis Hautesserres
Abstract: The algorithms used in the construction of a semi-analytical propagator for the long-term propagation of highly elliptical orbits (HEO) are described. The software propagates mean elements and include the main gravitational and non-gravitational effects that may affect common HEO orbits, as, for instance, geostationary transfer orbits or Molniya orbits. Comparisons with numerical integration show that it provides good results even in extreme orbital configurations, as the case of SymbolX.
PubDate: 2017-05-12
DOI: 10.1007/s12567-017-0152-x

• Developments of high frequency and intensity stabilized lasers for space
gravitational wave detector DECIGO/B-DECIGO
• Authors: Aru Suemasa; Ayumi Shimo-oku; Ken’ichi Nakagawa; Mitsuru Musha
Abstract: In Japan, not only the ground-based gravitational wave (GW) detector mission KAGRA but also the space GW detector mission DECIGO (DECi-hertz Interferometer Gravitational wave Observatory) and its milestone mission B-DECIGO have been promoted. The designed strain sensitivity of DECIGO and B-DECIGO are δL/L < 10−23. Since the GW detector requires high power and highly-stable light source, we have developed the light source with high frequency and intensity stability for DECIGO and B-DECIGO. The frequency of the Yb-doped fiber DFB lasers are stabilized to the iodine saturated absorption at 515 nm, and the intensity of the laser at 1 Hz (observation band) is stabilized by controlling the pump source of an Yb-doped fiber amplifier. The intensity of the laser at 200 kHz (modulation band) is also stabilized using an acousto-optic modulator to improve the frequency stability of the laser. In the consequences, we obtain the frequency stability of δf = 0.4 Hz/√Hz (in-loop) at 1 Hz, and the intensity stability of δI/I = 1.2 × 10−7/√Hz (out-of-loop) and δI/I = 1.5 × 10−7/√Hz (in-loop) at 1 Hz and 200 kHz, respectively.
PubDate: 2017-04-21
DOI: 10.1007/s12567-017-0151-y

• Exploratory numerical experiments with a macroscopic theory of interfacial
interactions
• Authors: D. Giordano; P. Solano-López; J. M. Donoso
Abstract: Phenomenological theories of interfacial interactions are founded on the core idea to model macroscopically the thin layer that forms between media in contact as a two-dimensional continuum (surface phase or interface) characterised by physical properties per unit area; the temporal evolution of the latter is governed by surface balance equations whose set acts as bridging channel in between the governing equations of the volume phases. These theories have targeted terrestrial applications since long time and their exploitation has inspired our research programme to build up, on the same core idea, a macroscopic theory of gas–surface interactions targeting the complex phenomenology of hypersonic reentry flows as alternative to standard methods in aerothermodynamics based on accommodation coefficients. The objective of this paper is the description of methods employed and results achieved in the exploratory study that kicked off our research programme, that is, the unsteady heat transfer between two solids in contact in planar and cylindrical configurations with and without interface. It is a simple numerical-demonstrator test case designed to facilitate quick numerical calculations but, at the same time, to bring forth already sufficiently meaningful aspects relevant to thermal protection due to the formation of the interface. The paper begins with a brief introduction on the subject matter and a review of relevant literature within an aerothermodynamics perspective. Then the case is considered in which the interface is absent. The importance of tension (force per unit area) continuity as boundary condition on the same footing of heat-flux continuity is recognised and the role of the former in governing the establishment of the temperature-difference distribution over the separation surface is explicitly shown. Evidence is given that the standard temperature-continuity boundary condition is just a particular case. Subsequently the case in which the interface is formed between the solids is analysed. The coupling among the heat-transfer equations applicable in the solids and the balance equation for the surface thermodynamic energy more conveniently formulated in terms of the surface temperature is discussed. Results are illustrated and commented for planar and cylindrical configuration; they show unequivocally that the thermal-protection action of the interface turns out to be driven exclusively by thermophysical properties of the solids and of the interface; accommodation coefficients are not needed. Future work of more fluid-dynamics nature is mentioned in the concluding section.
PubDate: 2017-04-10
DOI: 10.1007/s12567-017-0148-6

• Wavefront error measurement of the concave ellipsoidal mirrors of the
METIS coronagraph on ESA Solar Orbiter mission
• Authors: P. Sandri
Abstract: The paper describes the alignment technique developed for the wavefront error measurement of ellipsoidal mirrors presenting a central hole. The achievement of a good alignment with a classic setup at the finite conjugates when mirrors are uncoated cannot be based on the identification and materialization at naked eye of the retro-reflected spot by the mirror under test as the intensity of the retro-reflected spot results to be ≈1E−3 of the intensity of the injected laser beam of the interferometer. We present the technique developed for the achievement of an accurate alignment in the setup at the finite conjugate even in condition of low intensity based on the use of an autocollimator adjustable in focus position and a small polished flat surface on the rear side of the mirror. The technique for the alignment has successfully been used for the optical test of the concave ellipsoidal mirrors of the METIS coronagraph of the ESA Solar Orbiter mission. The presented method results to be advantageous in terms of precision and of time saving also when the mirrors are reflective coated and integrated into their mechanical hardware.
PubDate: 2017-04-09
DOI: 10.1007/s12567-017-0150-z

• Complex optical interference filters with stress compensation for space
applications
• Authors: Thomas Begou; Hélène Krol; Dragan Stojcevski; Fabien Lemarchand; Michel Lequime; Catherine Grezes-Besset; Julien Lumeau
Abstract: We present hereafter a study of complex bandpass optical interference filters with central wavelengths ranging in blue region or in the near infrared. For these applications, the required functions are particularly complex as they must present a very narrow bandwidth as well as a high level of rejection over a broad spectral range. Moreover, these components must have a good flatness meaning that the stress induced by the different layers has to be taken in account in the filter design. We present a thorough study of these filters including their design, fabrication using Plasma Assisted Reactive Magnetron Sputtering (PARMS) and characterization. Excellent agreement between experimental and theoretical spectral performances associated with a final sag of 326 and 13 nm, and uniformity from −0.05 to 0.10 and −0.10 to 0.20% are demonstrated for the two manufactured filters.
PubDate: 2017-04-07
DOI: 10.1007/s12567-017-0149-5

• Editorial
• Authors: Hansjörg Dittus
PubDate: 2017-02-09
DOI: 10.1007/s12567-017-0146-8

• Thanks to our Reviewers of the CEAS Space Journal
• PubDate: 2017-01-31
DOI: 10.1007/s12567-017-0144-x

• Cooperative rendezvous between two spacecraft under finite thrust
• Authors: Weiming Feng; Biao Wang; Kun Yang; Di Zhao
Abstract: Dynamic equations of orbital elements of a modified vernal equinox for a far-distance cooperative rendezvous between two spacecraft were set up in this paper. The process of the far-distance cooperative rendezvous was optimized by a hybrid algorithm combining particle swarm optimization and differential evolution. The convergent costate vectors were obtained and set as the initial values of sequential quadratic programming to search for precise solutions, and the results proved to be stable and convergent. It can be seen from the results that the flight time of the cooperative rendezvous would be largely saved the amplitude of the thrust would be increased if the other conditions are fixed, and the fuel consumption would not be increased. However, the flight time would no longer decrease when the amplitude of the thrust reaches a certain value. In the last section of this paper, cooperative rendezvous and active–passive rendezvous were compared and analyzed, showing the advantages of cooperative rendezvous when the initial conditions are the same.
PubDate: 2017-01-31
DOI: 10.1007/s12567-017-0145-9

• Analysis of the laser ignition of methane/oxygen mixtures in a sub-scale
rocket combustion chamber
• Authors: Michael Wohlhüter; Victor P. Zhukov; Joachim Sender; Stefan Schlechtriem
Abstract: The laser ignition of methane/oxygen mixtures in a sub-scale rocket combustion chamber has been investigated numerically and experimentally. The ignition test case used in the present paper was generated during the In-Space Propulsion project (ISP-1), a project focused on the operation of propulsion systems in space, the handling of long idle periods between operations, and multiple reignitions under space conditions. Regarding the definition of the numerical simulation and the suitable domain for the current model, 2D and 3D simulations have been performed. Analysis shows that the usage of a 2D geometry is not suitable for this type of simulation, as the reduction of the geometry to a 2D domain significantly changes the conditions at the time of ignition and subsequently the flame development. The comparison of the numerical and experimental results shows a strong discrepancy in the pressure evolution and the combustion chamber pressure peak following the laser spark. The detailed analysis of the optical Schlieren and OH data leads to the conclusion that the pressure measurement system was not able to capture the strong pressure increase and the peak value in the combustion chamber during ignition. Although the timing in flame development following the laser spark is not captured appropriately, the 3D simulations reproduce the general ignition phenomena observed in the optical measurement systems, such as pressure evolution and injector flow characteristics.
PubDate: 2016-12-27
DOI: 10.1007/s12567-016-0143-3

• Propulsive jet simulation with air and helium in launcher wake flows
• Authors: Sören Stephan; Rolf Radespiel
Abstract: The influence on the turbulent wake of a generic space launcher model due to the presence of an under-expanded jet is investigated experimentally. Wake flow phenomena represent a significant source of uncertainties in the design of a space launcher. Especially critical are dynamic loads on the structure. The wake flow is investigated at supersonic ( $$M=2.9$$ ) and hypersonic ( $$M=5.9$$ ) flow regimes. The jet flow is simulated using air and helium as working gas. Due to the lower molar mass of helium, higher jet velocities are realized, and therefore, velocity ratios similar to space launchers can be simulated. The degree of under-expansion of the jet is moderate for the supersonic case ( $$p_\mathrm{e}/p_\infty \approx 5$$ ) and high for the hypersonic case ( $$p_\mathrm{e}/p_\infty \approx 90$$ ). The flow topology is described by Schlieren visualization and mean-pressure measurements. Unsteady pressure measurements are performed to describe the dynamic wake flow. The influences of the under-expanded jet and different jet velocities are reported. On the base fluctuations at a Strouhal number, around $$\mathrm{St}_D \approx 0.25$$ dominate for supersonic free-stream flows. With air jet, a fluctuation-level increase on the base is observed for Strouhal numbers above $$\mathrm{St}_D \approx 0.75$$ in hypersonic flow regime. With helium jet, distinct peaks at higher frequencies are found. This is attributed to the interactions of wake flow and jet.
PubDate: 2016-12-24
DOI: 10.1007/s12567-016-0142-4

• Erratum to: Verification and validation of a parallel 3D direct simulation
Monte Carlo solver for atmospheric entry applications
• Authors: Paul Nizenkov; Peter Noeding; Martin Konopka; Stefanos Fasoulas
PubDate: 2016-11-22
DOI: 10.1007/s12567-016-0141-5

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