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  Subjects -> AERONAUTICS AND SPACE FLIGHT (Total: 101 journals)
Showing 1 - 30 of 30 Journals sorted alphabetically
Acta Astronautica     Hybrid Journal   (Followers: 265)
Advances in Space Research     Full-text available via subscription   (Followers: 305)
Aeronautica     Open Access   (Followers: 20)
Aerospace     Open Access   (Followers: 37)
Aerospace and Electronic Systems, IEEE Transactions on     Hybrid Journal   (Followers: 177)
Aerospace Science and Technology     Hybrid Journal   (Followers: 283)
AIAA Journal     Full-text available via subscription   (Followers: 697)
Air Force Magazine     Full-text available via subscription   (Followers: 7)
Air Medical Journal     Hybrid Journal   (Followers: 2)
Aircraft Engineering and Aerospace Technology     Hybrid Journal   (Followers: 137)
American Journal of Space Science     Open Access   (Followers: 103)
Annual of Navigation     Open Access   (Followers: 19)
Artificial Satellites : The Journal of Space Research Centre of Polish Academy of Sciences     Open Access   (Followers: 16)
ASTRA Proceedings     Open Access  
Aviation     Hybrid Journal   (Followers: 9)
Aviation Psychology and Applied Human Factors     Hybrid Journal   (Followers: 13)
Aviation Week     Full-text available via subscription   (Followers: 210)
Aviation, Space, and Environmental Medicine     Full-text available via subscription   (Followers: 7)
Canadian Aeronautics and Space Journal     Full-text available via subscription   (Followers: 25)
CEAS Aeronautical Journal     Hybrid Journal   (Followers: 26)
Chinese Journal of Aeronautics     Open Access   (Followers: 14)
Ciencia y Poder Aéreo     Open Access  
Control Systems     Hybrid Journal   (Followers: 86)
Cosmic Research     Hybrid Journal   (Followers: 2)
COSPAR Colloquia Series     Full-text available via subscription   (Followers: 6)
Egyptian Journal of Remote Sensing and Space Science     Open Access   (Followers: 19)
Elsevier Astrodynamics Series     Full-text available via subscription   (Followers: 2)
Fatigue of Aircraft Structures     Open Access   (Followers: 10)
Frontiers in Aerospace Engineering     Open Access   (Followers: 10)
Frontiers in Astronomy and Space Sciences     Open Access   (Followers: 8)
Giroskopiya i Navigatsiya     Open Access  
Gyroscopy and Navigation     Hybrid Journal   (Followers: 180)
IEEE Aerospace and Electronic Systems Magazine     Full-text available via subscription   (Followers: 118)
IEEE Transactions on Circuits and Systems I: Regular Papers     Hybrid Journal   (Followers: 21)
International Journal of Aeroacoustics     Hybrid Journal   (Followers: 27)
International Journal of Aerodynamics     Hybrid Journal   (Followers: 17)
International Journal of Aerospace Engineering     Open Access   (Followers: 63)
International Journal of Aerospace Innovations     Full-text available via subscription   (Followers: 17)
International Journal of Aerospace Sciences     Open Access   (Followers: 21)
International Journal of Applied Geospatial Research     Hybrid Journal   (Followers: 2)
International Journal of Aviation Management     Hybrid Journal   (Followers: 5)
International Journal of Aviation Psychology     Hybrid Journal   (Followers: 11)
International Journal of Aviation Technology, Engineering and Management     Full-text available via subscription   (Followers: 4)
International Journal of Crashworthiness     Hybrid Journal   (Followers: 7)
International Journal of Flow Control     Full-text available via subscription   (Followers: 5)
International Journal of Hypersonics     Full-text available via subscription   (Followers: 4)
International Journal of Micro Air Vehicles     Full-text available via subscription   (Followers: 7)
International Journal of Satellite Communications Policy and Management     Hybrid Journal   (Followers: 6)
International Journal of Space Science and Engineering     Hybrid Journal   (Followers: 4)
International Journal of Space Structures     Full-text available via subscription   (Followers: 6)
International Journal of Space Technology Management and Innovation     Full-text available via subscription   (Followers: 5)
International Journal of Sustainable Aviation     Hybrid Journal   (Followers: 1)
International Journal of Turbo & Jet-Engines     Hybrid Journal   (Followers: 3)
Journal of Aeronautical Materials     Open Access   (Followers: 2)
Journal of Aeronautics & Aerospace Engineering     Open Access   (Followers: 9)
Journal of Aerospace Engineering     Full-text available via subscription   (Followers: 54)
Journal of Aerospace Engineering & Technology     Full-text available via subscription   (Followers: 8)
Journal of Aerospace Information Systems     Full-text available via subscription   (Followers: 3)
Journal of Aerospace Technology and Management     Open Access   (Followers: 2)
Journal of Aircraft     Full-text available via subscription   (Followers: 177)
Journal of Airline and Airport Management     Open Access   (Followers: 7)
Journal of Astrobiology & Outreach     Open Access   (Followers: 1)
Journal of Aviation Technology and Engineering     Open Access   (Followers: 9)
Journal of Guidance, Control, and Dynamics     Full-text available via subscription   (Followers: 110)
Journal of Konbin     Open Access  
Journal of Navigation     Hybrid Journal   (Followers: 175)
Journal of Propulsion and Power     Full-text available via subscription   (Followers: 337)
Journal of Space Weather and Space Climate     Open Access   (Followers: 19)
Journal of Spacecraft and Rockets     Full-text available via subscription   (Followers: 487)
Journal of Spatial Science     Hybrid Journal   (Followers: 2)
Journal of the American Helicopter Society     Full-text available via subscription   (Followers: 3)
Journal of the Astronautical Sciences     Hybrid Journal   (Followers: 3)
Journal of Wind Engineering and Industrial Aerodynamics     Hybrid Journal   (Followers: 5)
Life Sciences in Space Research     Hybrid Journal  
MAD - Magazine of Aviation Development     Open Access  
Microgravity Science and Technology     Hybrid Journal  
New Space     Hybrid Journal   (Followers: 2)
Nonlinear Dynamics     Hybrid Journal   (Followers: 5)
npj Microgravity     Open Access  
Population Space and Place     Hybrid Journal   (Followers: 3)
Problemy Mechatroniki. Uzbrojenie, lotnictwo, inżynieria bezpieczeństwa / Problems of Mechatronics. Armament, Aviation, Safety Engineering     Open Access  
Proceedings of the Human Factors and Ergonomics Society Annual Meeting     Hybrid Journal   (Followers: 7)
Proceedings of the Institution of Mechanical Engineers Part G: Journal of Aerospace Engineering     Hybrid Journal   (Followers: 40)
Progress in Aerospace Sciences     Full-text available via subscription   (Followers: 68)
Propulsion and Power Research     Open Access   (Followers: 23)
REACH - Reviews in Human Space Exploration     Full-text available via subscription  
Recent Patents on Space Technology     Full-text available via subscription   (Followers: 1)
Research & Reviews : Journal of Space Science & Technology     Full-text available via subscription   (Followers: 6)
RocketSTEM     Free  
Russian Aeronautics (Iz VUZ)     Hybrid Journal   (Followers: 23)
Space and Polity     Hybrid Journal   (Followers: 3)
Space Policy     Hybrid Journal   (Followers: 24)
Space Research Today     Full-text available via subscription   (Followers: 40)
Space Safety Magazine     Free   (Followers: 40)
Space Science Reviews     Hybrid Journal   (Followers: 87)
SpaceNews     Free   (Followers: 500)
Transport and Aerospace Engineering     Open Access   (Followers: 5)
Transportmetrica A : Transport Science     Hybrid Journal   (Followers: 4)
Unmanned Systems     Hybrid Journal   (Followers: 1)
Вісник Національного Авіаційного Університету     Open Access   (Followers: 1)
Вестник УГАТУ     Open Access  

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Journal Cover CEAS Aeronautical Journal
  [SJR: 0.499]   [H-I: 6]   [26 followers]  Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 1869-5582
   Published by Springer-Verlag Homepage  [2335 journals]
  • State estimation for reactive Euler equation by Kalman Filtering
    • Authors: Jan- Simon Schäpel; Sascha Wolff; Philipp Schulze; Phillip Berndt; Rupert Klein; Volker Mehrmann; Rudibert King
      Abstract: Abstract In this article, we present a state estimation method for an approximately constant volume combustion process. This is an Unscented Kalman Filter used to estimate quantities which are of interest for the combustion process inside the considered combustion tube, i.e., the pressure, velocity and temperature field. This algorithm relies only on a small number of discrete pressure measurements along the combustion tube. The proposed methods are applied in numerical simulations to demonstrate their effectiveness. In a one-dimensional simulator, the flow field in the tube is described by the one-dimensional Euler equations with chemical source terms. To keep the computational effort on a manageable level, the Kalman Filter is built based on a reduced model. Thus, the model reduction for the Euler equations in combination with chemical kinetics is another focus of this contribution.
      PubDate: 2017-01-18
      DOI: 10.1007/s13272-016-0229-9
       
  • Numerical investigation of the vortex roll-up from a helicopter blade tip
           using a novel fixed-wing adaptation method
    • Authors: Antoine Joulain; Damien Desvigne; David Alfano; Thomas Leweke
      Abstract: Abstract This contribution relates to the simulation of the flow around the tip of a helicopter rotor blade in hovering flight conditions. We here propose a new methodology of framework adaptation, using a comprehensive rotor code and high-fidelity numerical simulations. We construct an equivalent fixed-wing configuration from a rotating blade, in which centrifugal and Coriolis forces are neglected. The effect of this approximation on the solution is analyzed. The method is validated by a detailed comparison with wind tunnel data from the literature, concerning aerodynamic properties and tip vortex roll-up. This validation also includes variations of the pitch angle and rotational speed, up to transonic tip velocities. Compared to previously published methods of framework adaptation, the new hybrid method is found to reproduce more accurately the flow around a rotating-blade tip.
      PubDate: 2017-01-07
      DOI: 10.1007/s13272-016-0234-z
       
  • Time-domain output error system identification of iced aircraft
           aerodynamics
    • Authors: Christoph Deiler
      Abstract: Abstract A \(\Delta\) -model approach to characterize changed aircraft dynamics due to icing is analytically derived and its parameters are estimated. The model extension is formulated as a separate module in the aircraft flight mechanics simulation and can be used in existing simulation models. The application of the output error method in time domain allows to satisfactorily match model outputs and measurements as well as calculated aerodynamic derivatives. Using available flight data of a light business jet with different ice accumulation cases provided by EMBRAER, model parameters of the \(\Delta\) -model are determined and interpreted pertaining to the aerodynamic degradation caused by icing. The results show good promise that the combination of modeling approach and estimation technique could be applicable to extend existing simulator models providing a basis for pilot training under icing conditions.
      PubDate: 2017-01-04
      DOI: 10.1007/s13272-016-0231-2
       
  • Design methodology for trailing-edge high-lift mechanisms
    • Authors: David Zaccai; Francesco Bertels; Roelof Vos
      Pages: 521 - 534
      Abstract: Abstract A new methodology has been developed that integrates the preliminary wing design with trailing edge high-lift systems and accounts for three-dimensional flap kinematics. The high-lift system in the developed application includes the kinematic synthesis of four common mechanisms (dropped-hinge, four-bar, link-track and hooked-track) and a preliminary actuation architecture. The paper details how each of these mechanisms is synthesized based on a set of intuitive input requirements such as gap and overlap dimensions in landing and take-off configuration. A SimMechanics multi-body mechanism model is generated to obtain the internal loads of the mechanism and actuation torque. The mechanisms and actuating drive train are structurally sized, leading to a determination of system weight and power consumption. A weight measurement of the outboard hooked-track mechanism of a VFW-614 flap has been compared to a modeled hooked-track mechanism by using the proposed method. This resulted in a 13 % underestimation of the mechanism weight, which was attributed to modeling simplifications, sizing assumptions and a crude aerodynamic load estimation. A comparison study between the four different mechanism types to be applied on a Boeing 777 wing, shows that the method can give the designer valuable insight in the gap/overlap behavior of the flap during deployment as well as an initial estimation of the difference in required fairing size, mechanism weight, and actuation power between the four mechanisms.
      PubDate: 2016-12-01
      DOI: 10.1007/s13272-016-0202-7
      Issue No: Vol. 7, No. 4 (2016)
       
  • Impact of pulsed jet actuators on aircraft mass and fuel consumption
    • Authors: Francesco G. A. Bertels; Reinier van Dijk; Reno Elmendorp; Roelof Vos
      Pages: 535 - 549
      Abstract: Abstract Pulsed jet actuators (PJAs) are one of the candidate technologies to be integrated in Fowler flaps to increase the maximum lift coefficient of transport aircraft in the landing configuration. The total system consists of the actuators plus sensors, a piping system to supply pressurized air and a (redundant) power and communication system to provide actuator control. In this paper, it is investigated what increase in the maximum lift coefficient is required to justify the added weight and power off-takes that accompany the integration of pulsed jet actuators. This is done by making an automated design process for the overall aircraft, the piping assembly system, and the electrical wiring interconnection system. These last two sub-systems rely on KBE techniques that automate dimensioning and performance evaluation. A test case is specified that encompasses the design of a typical single-aisle mid-range aircraft with and without the PJA system installed. It is concluded that the introduction of the PJA system requires at least an increase in maximum lift coefficient of 0.2 to justify the increase in system mass and power off-takes. Furthermore, it is shown that if the maximum lift coefficient increases with 0.4, only small reductions in maximum take-off weight (−0.3 %) and operating empty weight (−0.6 %) can be expected, while the total fuel burn remains virtually constant.
      PubDate: 2016-12-01
      DOI: 10.1007/s13272-016-0201-8
      Issue No: Vol. 7, No. 4 (2016)
       
  • Investigation of a simplified aerodynamic modelling technique for noise
           predictions using FW–H propagation
    • Authors: Jianping Yin; Berend G. van der Wall; Gunther A. Wilke
      Pages: 551 - 566
      Abstract: Abstract This paper addresses the influence of the elastic rotor blade deformation and the aerodynamic interference from the fuselage on the rotor aerodynamics, including rotor noise characteristics. A BO105 main rotor/fuselage configuration is chosen for the numerical simulations. An unsteady aerodynamic code based on free wake three-dimensional panel method (UPM) is used to account for nonlinear effects associated with the mutual interference between main rotor and fuselage. Airbus Helicopters’ (formerly: Eurocopter) rotor code (HOST) is coupled with this aerodynamic code (UPM) to account for the effect of elastic blade deformation. The effect of the fuselage is simulated using two fuselage models in aerodynamic code, (1) potential theory in the form of a panelized fuselage and (2) an analytic fuselage influence formulation derived from isolated fuselage simulation. The advantage of (2) is in its computational efficiency. The aerodynamic modelling is then coupled with an aero-acoustic post-processing tool based on the Ffowcs-Williams–Hawkings (FW–H) approach for evaluating the noise propagation to the far-field. This toolchain is then evaluated in different flight conditions to assess the usability of this approach in the design process. In descending flight, the acoustic prediction is completed at a very mature level, as the blade vortex interaction is well captured. In climb, the major noise peak is underpredicted, while the overall directivity agreement is well matched. In forward flight, due to a phase shift in the airloads prediction, parts of the loading noise directivity are not well captured. The onset of transonic effects further degrades the results obtained at the front of the rotor. For the investigated flight cases, the analytical fuselage formulation brought very similar results to the panelized fuselage model, therefore proving its worthiness for further accelerating the simulation in these flight conditions.
      PubDate: 2016-12-01
      DOI: 10.1007/s13272-016-0208-1
      Issue No: Vol. 7, No. 4 (2016)
       
  • Fiber-reinforced polymers with integrated shape memory alloy actuation: an
           innovative actuation method for aerodynamic applications
    • Authors: M. Hübler; S. Nissle; M. Gurka; U. Breuer
      Pages: 567 - 576
      Abstract: Abstract This contribution focuses on the application potential of active fiber-reinforced polymer (FRP) structures with integrated shape memory alloy (SMA) elements for new aerodynamic functions. The advantages of hybrid SMA FRP structures are highlighted, and promising application concepts are discussed. To illustrate the applicability of the technology, the developed manufacturing, design, and control approaches are presented. Main focus is the development of a new concept for an active aerodynamic airfoil and the realization of a hardware demonstrator. Beginning with the idea of an adaptive airfoil, able to bear an application relevant down force at a relatively high deflection, the design process starts with an evaluation of different actuation concepts. An SMA-powered cantilever is a part of the profile itself. Applying the finite-element method with a suitable model for the active hybrid material, an effective selection of material and design is possible. After manufacturing and assembling of the active hybrid airfoil, a comparison of experimental results and simulation is the first proof of success. Finally, the installation of an integrated hardware setup with power source, control, and the active hybrid structure, demonstrating actuation on demand, verifies the potential and the distinct advantages of the new approach using SMA FRP structures.
      PubDate: 2016-12-01
      DOI: 10.1007/s13272-016-0209-0
      Issue No: Vol. 7, No. 4 (2016)
       
  • Analysis of dry-spot behavior in the pressure field of a liquid composite
           molding process
    • Authors: D. Bertling; R. Kaps; E. Mulugeta
      Pages: 577 - 585
      Abstract: Abstract Due to industrial automation of liquid composite molding processes and increasing geometrical complexity of composite components, dry-spots from flow front junctions have become increasingly difficult to avoid. The impact and behavior of voids (microscopic or small macroscopic gas entrapments) during preform impregnation is well known, but no attention is given to dry-spots (large macroscopic gas entrapments). Experiments show that formation of a dry-spot in an early stage of an injection process does not necessarily lead to scrap parts. Therefore, simulation-based predictions of dry-spots are no sufficient condition for identification of unsuitable injection strategies. In this paper, the resolution mechanisms of dry-spots under controlled process conditions are investigated and the resulting findings of fundamental formation- and dispersion-mechanisms are presented.
      PubDate: 2016-12-01
      DOI: 10.1007/s13272-016-0207-2
      Issue No: Vol. 7, No. 4 (2016)
       
  • Handling qualities evaluation of an automatic slung load stabilization
           system for rescue hoist operations
    • Authors: D. Nonnenmacher; M. Jones
      Pages: 587 - 606
      Abstract: Abstract The Handling Qualities (HQs) of a helicopter can be adversely affected through the presence of an externally slung load. Helicopter stability margins may be reduced, due to the additional dynamics of the load system, which can subsequently increase pilot workload, and reduce the operational envelope. An Automatic Load Damping System (ALDS) has been designed and has been successfully tested in flight. This system, alongside slung load scenarios, has been implemented within a piloted simulation in DLR’s Air Vehicle Simulator. In this article, the results from a simulated test campaign to observe the influence of the stabilization system on the vehicle HQs are presented. The system is assessed using three Mission Task Elements, modified for hoist operations. Results show that a conflict between pilot control and commanded inputs from the ALDS can cause unstable slung load oscillations and degradation in HQs in hover. However, it is shown that when the stabilization system is used only when required, both the HQs of the helicopter are conserved, and load oscillations are reduced. The results in this paper are intended to motivate future flight tests using DLR’s Active Control Technology/Flying Helicopter Simulator.
      PubDate: 2016-12-01
      DOI: 10.1007/s13272-016-0211-6
      Issue No: Vol. 7, No. 4 (2016)
       
  • Multiscale virtual testing: the roadmap to efficient design of composites
           for damage resistance and tolerance
    • Authors: C. S. Lopes; C. González; O. Falcó; F. Naya; J. LLorca; B. Tijs
      Pages: 607 - 619
      Abstract: Abstract This paper proposes a novel approach to the determination of the mechanical behaviour of composite materials up to failure using numerical and experimental techniques in parallel. A bottom-up multiscale virtual testing strategy is presented to take into account the physical mechanisms of deformation at different length scales on the behaviour of the composite. Starting from the microscale, the contributions of the basic constituents, microstructure and loading conditions to the mechanical response are considered in a rigorous way. This hierarchical multiscale approach describes systematically the material behaviour at different length scales from ply to laminate to component level, allowing the determination of ply properties, laminate characteristics and structural response. Additionally, this approach easily allows consideration of changes in properties of the constituents (fibre, matrices), fibre architecture or laminate lay-up and provides fast predictions of their influences on the macroscopic behaviour of composite structures. Hence, this approach constitutes a promising tool to provide significant efficiency gains in the design, testing and certification of composite aircraft structures.
      PubDate: 2016-12-01
      DOI: 10.1007/s13272-016-0210-7
      Issue No: Vol. 7, No. 4 (2016)
       
  • Characteristic flight speeds in bats
    • Authors: R. D. Bullen; N. L. McKenzie; A. P. Cruz-Neto
      Pages: 621 - 643
      Abstract: Abstract We present empirical data on flight speed for 30 species of Australian bats representing seven families. These data show five characteristic level flight speeds: ‘minimum’ (V min), ‘best efficiency’ (V eff), ‘most common’ (V mode), ‘maximum cruise’ (V mcr) and ‘maximum spurt’ (V msp). Next, we calculate V min, V eff, ‘maximum aerobic’ (V ae), ‘sustainable anaerobic’ (V san ) and ‘maximum anaerobic’ (V man) flight speeds using a published quasi-steady model. Model predictions were within 0.5 m s−1 of the empirical values for all five characteristic speeds given adequate samples. Model fidelity was cross-checked using flight speed data published for other Old and New World species.
      PubDate: 2016-12-01
      DOI: 10.1007/s13272-016-0212-5
      Issue No: Vol. 7, No. 4 (2016)
       
  • Decision-making for unmanned aerial vehicle operation in icing conditions
    • Authors: S. F. Armanini; M. Polak; J. E. Gautrey; A. Lucas; J. F. Whidborne
      Pages: 663 - 675
      Abstract: Abstract With the increased use of unmanned aerial systems (UAS) for civil and commercial applications, there is a strong demand for new regulations and technology that will eventually permit for the integration of UAS in unsegregated airspace. This requires new technology to ensure sufficient safety and a smooth integration process. The absence of a pilot on board a vehicle introduces new problems that do not arise in manned flight. One challenging and safety-critical issue is flight in known icing conditions. Whereas in manned flight, dealing with icing is left to the pilot and his appraisal of the situation at hand; in unmanned flight, this is no longer an option and new solutions are required. To address this, an icing-related decision-making system (IRDMS) is proposed. The system quantifies in-flight icing based on changes in aircraft performance and measurements of environmental properties, and evaluates what the effects on the aircraft are. Based on this, it determines whether the aircraft can proceed, and whether and which available icing protection systems should be activated. In this way, advice on an appropriate response is given to the operator on the ground, to ensure safe continuation of the flight and avoid possible accidents.
      PubDate: 2016-12-01
      DOI: 10.1007/s13272-016-0215-2
      Issue No: Vol. 7, No. 4 (2016)
       
  • Multidisciplinary design and aerodynamic assessment of an agile and highly
           swept aircraft configuration
    • Authors: C. M. Liersch; K. C. Huber; A. Schütte; D. Zimper; M. Siggel
      Pages: 677 - 694
      Abstract: Abstract The characteristics of highly swept aircraft configurations have been studied in a series of consecutive research projects in DLR for more than 15 years. Currently, the investigations focus on the generic SACCON UCAV configuration, which was specified in a common effort together with the NATO STO/AVT-161 task group. This paper is the first one in a series of articles presenting the SACCON-related research work within DLR. First, the article describes the conceptual design studies being performed for this aircraft configuration. At this point the question is raised, whether the simple aerodynamic methods used within conceptual design can be applied to such type of aircraft configurations with sufficient accuracy. Thus, the second part of this article provides a comparison of the aerodynamic characteristics of the SACCON configuration predicted by low- and high-fidelity aerodynamic methods, as well as some results from wind tunnel experiments.
      PubDate: 2016-12-01
      DOI: 10.1007/s13272-016-0213-4
      Issue No: Vol. 7, No. 4 (2016)
       
  • Identification of rotor wake inflow finite-state models for flight
           dynamics simulations
    • Authors: Massimo Gennaretti; Riccardo Gori; Jacopo Serafini; Felice Cardito; Giovanni Bernardini
      Abstract: Abstract The aim of this work is the development of dynamic, finite-state modelling of wake inflow generated by kinematic perturbations of rotors in steady flight conditions. Extracted from responses of high-fidelity aerodynamic solvers, it is suited for flight dynamics applications. A three-step identification procedure is proposed: (1) evaluation by a high-fidelity solver of the wake inflow due to harmonic perturbations of rotor kinematics, (2) determination of the corresponding inflow coefficient transfer functions, and (3) rational approximation of the transfer functions. Wake inflow models related to rotor loads (like the well-known Pitt–Peters model) are obtained, as well, as by-products of that proposed. Considering aerodynamic simulations provided by a solver based on a boundary element method for potential flows, the numerical investigation presents the validation of the proposed finite-state wake inflow modelling, along with the examination of identified models related to rotor loads, for a rotor in steady flight conditions subject to arbitrary perturbations.
      PubDate: 2016-12-22
      DOI: 10.1007/s13272-016-0235-y
       
  • Closed-loop active flow control of a non-steady flow field in a
           highly-loaded compressor cascade
    • Authors: M. Staats; W. Nitsche; S. J. Steinberg; R. King
      Abstract: Abstract The provision of secure compressor operation under circumstances of a pulsed detonation engine is crucial for the success of pressure gaining combustion processes for turbo machinery applications. This paper discusses active flow control as a possible solution to approach this challenge. The presented experiments were conducted on a highly loaded low speed linear compressor stator cascade operated at \(Re=600{,}000\) and \(Ma =0.07\) . A choking-device which was located in the wake of the cascade simulated the non-steady outflow condition that is expected under the conditions of pressure gaining combustion. In the discussed experiments, the choking-device generated a periodic disturbance to every passage at a typical Strouhal number of \(Sr =0.03\) . The flow structures of the non-steady flow field were strongly correlated to the working-phase of the choking-device. In this paper, an iterative learning controller was used to find an optimized actuation trajectory that was used for closed-loop sidewall-actuation to control the corner separation in the non-steady flow field. The iterative learning controller took advantage of the periodicity of the disturbance to calculate a non-steady actuation trajectory that optimally suppressed the impact of the choking-device on the flow. The active flow control effect was evaluated by means of static pressure rise using five hole probe measurements in the wake of one passage.
      PubDate: 2016-12-22
      DOI: 10.1007/s13272-016-0232-1
       
  • Rotor performance enhancement via localized pitch control and its effects
           on hub vibrations and pitch link loads
    • Authors: Philip Küfmann; Rainer Bartels; Berend G. van der Wall
      Abstract: Abstract This paper presents an approach to enhance rotor performance and reduce vibration levels at the rotor hub by introducing local blade pitch variations at specific azimuthal locations. Two different variants of these “localized pitch control” (LPC) functions are presented and their effects both on rotor performance and vibrational loads are studied using parametric variation and subsequent numerical optimization of the respective LPC signals. The results are compared with those obtained from a conventional approach using 2/rev higher harmonic control (HHC). Numerical calculations were performed using the DLR’s comprehensive rotor code S4 with a modified Beddoes inflow-model simulating an isolated hingeless rotor at an advance ratio of µ = 0.382. In those simulations power reductions of up to 7.61 and 3.36% could be reached using two sets of different model rotor blades. Both for power reduction and simultaneous reduction of power and 4/rev vibrational loads, LPC performed slightly better than conventional 2/rev HHC but also resulted in higher actuation demands which have to be taken into account for real-world applications of LPC.
      PubDate: 2016-12-21
      DOI: 10.1007/s13272-016-0233-0
       
  • About the emissions of alternative jet fuels
    • Authors: Marina Braun-Unkhoff; Uwe Riedel; Claus Wahl
      Abstract: Abstract In the last years, several alternative aviation jet fuels have been approved as a response to worldwide concerns on adverse environmental effects of greenhouse gas emissions. However, comprehensive emissions studies are not part of the approval process. When burning a jet fuel, the exhaust gases are a mixture of gaseous specious including aromatics and non-gaseous species, particles, and soot. In addition, these species may affect the growth and lifetime of contrails known to be of influence on the climate due to their radiative forcing. Within this context, the use of synthetic aviation fuels may offer several advantages, going beyond reduced CO2 emissions. These issues were addressed by studying the combustion of synthetic jet fuels taking into account their individual composition. An overview of what is known on their emission pattern was presented. Mostly, the same general trends were reported for the emissions of interest, for the fuels considered and at the power settings selected, with no adverse emissions effects. In particular, less soot particle emissions were reported, in mass and in number concentration, for GtL, HEFA, and farnesane. Moreover, a strong link between the amount and type of aromatics content of a jet fuel and soot emissions was observed.
      PubDate: 2016-12-19
      DOI: 10.1007/s13272-016-0230-3
       
  • Fan casing contouring under consideration of aeroacoustics, mechanics,
           aeroelasticity, and whole engine performance
    • Authors: A.-L. Aulich; T. Sauer; S. Iseni; A. Moreau; D. Peitsch; R. Mailach; D. Micallef; L. Enghardt; E. Nicke
      Abstract: Abstract Aircraft propulsion will continue to rely on gas turbine technology for the next decades to come. Thus, to achieve environmental agreements, ensure engine safety, and retain economic competitiveness, ongoing development with a multidisciplinary design approach is indispensable. In the present study, the multi-criteria analysis of the fan, a decisive component in modern aero engines, is examined. In particular, the interaction of the fan blades with the fan casing is analyzed and an appropriate design approach, including automatic optimization, is used. As one part of the disciplines conjunction, an automated aeroacoustic approach is realized. The aerodynamic and acoustic fitness functions and constraints are based on Reynolds-Averaged Navier–Stokes (RANS) simulations of the fan stage. PropNoise, a fast analytical prediction tool for fan noise, is used. It has been under development since recent years and is already validated on several test cases. Preliminary studies have shown that the flow in the rotor tip region is a major contributor to the broadband noise emission. Based on this, the optimization process focuses on the variation of the casing contour around the fan blades. The impact of the modified flow field in the rotor tip region concerning the aeroelastic behavior is also investigated. As aeroelastic evaluation requires a high level of know-how and is very time consuming, it is linked to the optimization process chain by a discrete evaluation of selected members. This allows a simultaneous adjustment of the design in case of aeroelastic issues. Furthermore, the impact of the fan modifications regarding the overall engine performance is evaluated. Off-design cycle calculations allow incorporating such detailed studies in a global engine optimization.
      PubDate: 2016-12-08
      DOI: 10.1007/s13272-016-0226-z
       
  • Development of flow structures in the near-field wake region of the Common
           Research Model
    • Authors: D.-M. Zimmermann; A. Waldmann; T. Lutz; E. Krämer
      Abstract: Abstract The flow in the near-field wake region of a generic transport aircraft configuration has been studied using both unsteady RANS and delayed detached-eddy simulations. The NASA Common Research Model has been used for this purpose, as experimental data obtained with this model in the cryogenic European Transonic Wind Tunnel during the ESWIRP test campaign were available for comparison and validation. Focusing on high angles of attack of \(\alpha = 16^\circ\) and \(\alpha = 18^\circ\) , the results form the basis for the study of flow phenomena occurring at stall conditions. Such flight conditions are characterized by massive flow separation at the wing and highly unsteady flow in the wake. In a first step, the numerical results are compared with available test data using global force coefficients and pressure distributions on the wing. Both show a good agreement of numerical and experimental results, indicating slight deviations of the pressure variable at the inboard wing sections. In a second step, the turbulent structures of the near-field wake are examined using the proper orthogonal decomposition method based on snapshots (two-dimensional instantaneous flow fields). Frequencies of the first mode-pair match the dominant frequencies of the lift and velocity wake spectra very well.
      PubDate: 2016-12-05
      DOI: 10.1007/s13272-016-0222-3
       
  • The promised future of multi-core processors in avionics systems
    • Authors: O. Sander; F. Bapp; L. Dieudonne; T. Sandmann; J. Becker
      Abstract: Abstract Modern airplanes need to satisfy rising requirements in terms of functionality and fuel efficiency per passenger. Therefore, an ever-increasing amount of electronics is being integrated in the airplanes either by adding new functionalities or by exchanging mechanical systems by more complex and highly integrated mechatronic ones, optimizing the space, weight and energy used by the airplane infrastructure. Embedded computers are the base of this development and have to perform more and more tasks with at least the same safety characteristics as before. In the last 15 years, different functions traditionally realized in separated devices must be grouped together in one device to limit the ever-increasing number of computers in new airplanes. For safety reasons, this has only been done based on single-core processors up to now: the multi-core technology cannot insure the same level of confidence as single-core controllers—it was mainly invented to gain performance. But the performance of the current single-core processors adequate for embedded and safety–critical applications is limited and, therefore, restricts the grouping of applications. The automotive industry is confronted with similar but still stronger increasing performance challenges. In this sector, the multi-core processors are already considered as the only known solution to fulfill the rising requirements and are, therefore, expected to completely replace single-core processors in a few years. Specific multi-core processor architectures and functionalities improving safety capabilities have recently been developed. The goal of this contribution is to show how the avionics might benefit from using these safety-oriented automotive multi-core processors.
      PubDate: 2016-12-02
      DOI: 10.1007/s13272-016-0228-x
       
 
 
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