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 Subjects -> AERONAUTICS AND SPACE FLIGHT (Total: 93 journals)
 Acta Astronautica       (Followers: 375) Advances in Space Research       (Followers: 393) Aeronautica       (Followers: 5) Aerospace       (Followers: 6) Aerospace and Electronic Systems, IEEE Transactions on       (Followers: 59) Aerospace Science and Technology       (Followers: 385) Affective Computing, IEEE Transactions on       (Followers: 9) AIAA Journal       (Followers: 608) Air Force Magazine       (Followers: 2) Air Medical Journal       (Followers: 2) Aircraft Engineering and Aerospace Technology       (Followers: 182) American Journal of Space Science       (Followers: 37) Annual of Navigation       (Followers: 1) Artificial Satellites       (Followers: 15) ASTRA Proceedings Aviation       (Followers: 4) Aviation in Focus - Journal of Aeronautical Sciences       (Followers: 2) Aviation Psychology and Applied Human Factors       (Followers: 5) Aviation Week       (Followers: 12) Aviation, Space, and Environmental Medicine       (Followers: 5) Canadian Aeronautics and Space Journal       (Followers: 15) CEAS Aeronautical Journal       (Followers: 24) Chinese Journal of Aeronautics       (Followers: 11) Control Systems       (Followers: 21) Cosmic Research       (Followers: 2) COSPAR Colloquia Series       (Followers: 1) Egyptian Journal of Remote Sensing and Space Science       (Followers: 5) Elsevier Astrodynamics Series       (Followers: 1) Fatigue of Aircraft Structures       (Followers: 5) Frontiers in Aerospace Engineering       (Followers: 5) Frontiers in Astronomy and Space Sciences Gyroscopy and Navigation       (Followers: 36) IEEE Aerospace and Electronic Systems Magazine       (Followers: 40) IEEE Transactions on Circuits and Systems I: Regular Papers       (Followers: 9) International Journal of Aeroacoustics       (Followers: 6) International Journal of Aerodynamics       (Followers: 11) International Journal of Aerospace Engineering       (Followers: 43) International Journal of Aerospace Innovations       (Followers: 11) International Journal of Aerospace Sciences       (Followers: 16) International Journal of Applied Geospatial Research       (Followers: 4) International Journal of Aviation Management       (Followers: 2) International Journal of Aviation Psychology       (Followers: 4) International Journal of Aviation Technology, Engineering and Management International Journal of Crashworthiness       (Followers: 4) International Journal of Flow Control       (Followers: 2) International Journal of Hypersonics       (Followers: 3) International Journal of Micro Air Vehicles       (Followers: 4) International Journal of Satellite Communications Policy and Management International Journal of Space Science and Engineering       (Followers: 2) International Journal of Space Structures       (Followers: 3) International Journal of Space Technology Management and Innovation       (Followers: 2) International Journal of Sustainable Aviation International Journal of Turbo & Jet-Engines ISRN Astronomy and Astrophysics       (Followers: 11) Journal of Aerospace Computing, Information, and Communication       (Followers: 12) Journal of Aerospace Engineering       (Followers: 187) Journal of Aerospace Engineering & Technology Journal of Aerospace Operations       (Followers: 4) Journal of Aerospace Technology and Management       (Followers: 1) Journal of Aircraft       (Followers: 351) Journal of Airline and Airport Management       (Followers: 3) Journal of Aviation Technology and Engineering       (Followers: 6) Journal of Guidance, Control, and Dynamics       (Followers: 63) Journal of Konbin Journal of Navigation       (Followers: 39) Journal of Propulsion and Power       (Followers: 280) Journal of Space Weather and Space Climate       (Followers: 4) Journal of Spacecraft and Rockets       (Followers: 400) Journal of Spatial Science       (Followers: 1) Journal of the American Helicopter Society       (Followers: 1) Journal of the Astronautical Sciences       (Followers: 2) Microgravity Science and Technology New Space       (Followers: 2) Nonlinear Dynamics       (Followers: 5) Population Space and Place       (Followers: 2) Proceedings of the Human Factors and Ergonomics Society Annual Meeting       (Followers: 1) Proceedings of the Institution of Mechanical Engineers Part G: Journal of Aerospace Engineering       (Followers: 24) Progress in Aerospace Sciences       (Followers: 48) Propulsion and Power Research       (Followers: 2) Recent Patents on Space Technology Research & Reviews : Journal of Space Science & Technology Russian Aeronautics (Iz VUZ)       (Followers: 15) Space and Polity       (Followers: 2) Space Communications       (Followers: 2) Space Policy       (Followers: 16) Space Research Today       (Followers: 26) Space Safety Magazine       (Followers: 4) Space Science Reviews       (Followers: 13) SpaceNews       (Followers: 260) Transport and Aerospace Engineering Transportmetrica A : Transport Science       (Followers: 1) Вісник Національного Авіаційного Університету       (Followers: 2) Вестник УГАТУ
 CEAS Aeronautical Journal      [26 followers]  Follow        Hybrid journal (It can contain Open Access articles)    ISSN (Print) 1869-5582    Published by Springer-Verlag  [2210 journals]
• Synergies between suction and blowing for active high-lift flaps
• Abstract: Abstract The present 2-D CFD study investigates aerodynamic means for improving the power efficiency of an active high-lift system for commercial aircraft. The high-lift configuration consists of a simple-hinged active Coanda flap, a suction slot, and a flexible droop nose device. The power required to implement circulation control is provided by electrically driven compact compressors positioned along the wing behind the wingbox. The compact compressors receive air from the suction slot, which also represents an opportunity to increase the aerodynamic performance of the airfoil. The present work investigates the aerodynamic sensitivities of shape and location of the suction slot in relation to the maximum lift performance of the airfoil. The main purpose of the study is the reduction of the compressor power required to achieve a target lift coefficient. The compressor power requirements can be reduced in two ways: obtaining a high total pressure at the end of the suction duct (compressor inlet) and reducing the momentum needed by the Coanda jet to avoid flow separation from the flap. These two objectives define the guideline of the suction slot design. As a result, a jet momentum reduction of 16 % was achieved for a target lift coefficient of 5 with respect to the same configuration without suction. Furthermore, the study yielded physical insight into the aerodynamic interaction between the two active flow control devices.
PubDate: 2015-01-10

• Influence of boundary layer transition on the flutter behavior of a
supercritical airfoil
• Abstract: Abstract This paper presents a flutter analysis for the supercritical CAST 10-2 airfoil in a flow with free boundary layer transition based on CFD computations with the $$\gamma$$ - $$\hbox {Re}_{\theta }$$ transition model. The results are compared to fully turbulent results obtained with the SST $$k$$ - $$\omega$$ turbulence model. Unsteady RANS computations at $$\hbox {Re}_{\rm{c}} = 2 \times 10^{6}$$ are used to determine the aerodynamic derivatives. These derivatives are required to identify the flutter boundary for a 2 degree-of-freedom model by a k method. The transonic flutter boundary decreases for a flow with free boundary layer transition compared to a fully turbulent flow in the vicinity of the transonic dip. However, the flutter boundary at subsonic Mach numbers is raised for a transitional flow. In addition, the transitional frequency response is discussed: an aerodynamic resonance in connection with an instability of the transition region is observed and the possibility of a 1 degree-of-freedom flutter for transitional flows is shown.
PubDate: 2015-01-07

• Hybrid-electric propulsion for automotive and aviation applications
• Abstract: Abstract In parallel with the automotive industry, hybrid-electric propulsion is becoming a viable alternative propulsion technology for the aviation sector and reveals potential advantages including fuel savings, lower pollution, and reduced noise emission. Hybrid-electric propulsion systems can take advantage of the synergy between two technologies by utilizing both internal combustion engines and electric motors together, each operating at their respective optimum conditions. However, there can also be disadvantages to hybrid propulsion. We are conducting an analysis of hybrid-electric propulsion for aircraft, which is looking at modelling systems over a range of aircraft scale, from small UAVs to inter-city airliners. To support the theoretical models, a mid-scale hybrid-electric propulsion system for a single-seat manned aircraft is being designed, built, and tested to generate data for validation and development of the simulation models. This paper draws parallels between the synergy of hybrid-electric propulsion for automotive and aviation applications, and presents an innovative theoretical approach integrating several desktop PC software packages to analyse and optimize hybrid-electric technology for aircraft. Our findings to date indicate that hybrid-electric propulsion can have a significant impact in the small- and mid-scale sectors, but only a minor impact in the large-scale sector assuming battery energy densities predicted for the next decade. Fuel savings of up to 50 and 10 % have been calculated for a microlight aircraft and inter-city airliner, respectively, over the mission profiles considered.
PubDate: 2014-12-30

• Simulation of thermal behavior during friction stir welding process for
predicting residual stresses
• Abstract: Abstract Using a transient thermal finite element analysis, the thermal behavior during friction stir welding (FSW) of aluminum sheets for aerospace applications was calculated. The thermal behavior during the FSW process is of interest for all aspects of distortion engineering or microstructural interpretations for material design. In the presented approach to determine the amount of deformation caused by the thermal residual stresses only, the measured temperature history of the welding tool, the thermomechanical material properties and the thermal contact properties have to be known. Since the calculated time-dependent temperature distribution agrees very well with experimentally measured temperatures at seven different locations during a FSW experiment, it is concluded that the model accurately predicts the thermal history during welding. In addition, a first attempt to calculate the distortion, due to thermal residual stresses, is presented and compared to experimentally measured distortion. Although the calculated values of the distortion are too low compared to experimental results, the approach gives a first impression on the origin of the distortion and will be pursued in further investigations.
PubDate: 2014-12-27

• Modeling flows in low-pressure turbine cascades at very low Reynolds
numbers
• Abstract: Abstract This paper presents how transitional flows occurring inside low-pressure turbine cascades can be successfully simulated within a RANS framework. In particular, the emphasis will be put on cascades designed to operate at very low Reynolds numbers. Since such flows are difficult to model, a three-equation model Pacciani et al. (J Turbomach 133(3):031016, 2011), using the concept of laminar kinetic energy has been implemented into DLR in-house turbomachinery specific CFD code TRACE. The detailed implementation of the model and the first results are presented in this paper. The new model has been validated on the T106C turbine cascade. Like in the publication of Pacciani et al, short, long and open separation bubbles are well reproduced. A further assessment of the capability of the model has been carried out: two industrial relevant cascades have been computed. The first blade is an aft-loaded profile while the second blade is a front-loaded profile. For both design types, the agreement between the experiments and the computations is good at low Reynolds number. Notably, the long separation bubble found on the aft-loaded blade is well reproduced. At high values of the Reynolds number, discrepancies occur and are discussed.
PubDate: 2014-12-27

• Methods for simulation and analysis of hybrid electric propulsion systems
• Abstract: Abstract Today, research performed for new aircraft propulsion concepts is driven by the requirement of achieving significant emission reductions to meet the environmental objectives of future air traffic. A current trend visible in the aviation industry shows the attempt to reduce inflight emissions as well as overall energy consumption of conventional combustion engines through electrification via electrical energy sources. With the growing interest in novel hybrid electric propulsion concepts, in the same way, a demand for conceptual design and performance simulation methods in combination with analysis capabilities rises. Based on primarily introduced and discussed hybrid electric propulsion systems, this paper presents a set of aircraft propulsion system simulation (APSS) methods which allow for an integrated simulation and consistent analysis. Particularly, methods for the modelling of electric motor and battery systems as implemented in APSS are described in detail.
PubDate: 2014-12-25

• Characteristics of PEMFC operation in ambient- and low-pressure
environment considering the fuel cell humidification
• Abstract: Abstract This paper summarizes experimental results of an air-fed polymer electrolyte membrane fuel cell system HyPM XR 12 (Hydrogenics Corp.) considering fuel cell temperature, stoichiometry, and load requirement variations at ambient and low-pressure operation. The experimental work realized at a low-pressure test facility designed and assembled by the German Aerospace Center, Institute of Engineering Thermodynamics is based on an experimental design. The experimental results confirm reduced fields of fuel cell operation as well as a decreased gross stack performance and efficiency at low operating pressures (950 mbar ≥ p ≥ 600 mbar) for the defined fuel cell temperature, stoichiometry, and load requirement. In addition, indexes of the operating parameters are introduced, characterizing the fuel cell operation with regard to the gross stack performance and efficiency at ambient and low-pressure levels. The discussion of the results considers analyses of fuel cell humidification.
PubDate: 2014-12-05

• Correction of aerodynamic influence matrices for transonic flow
• Abstract: Abstract The authors present a novel correction approach for the doublet-lattice method in this paper. The doublet-lattice method is a standard tool for calculating unsteady aerodynamic loads in aeroelasticity. It solves the linear potential equations and is thus valid only at subsonic flow conditions. Hence, corrections have to be applied for transonic flow. The proposed correction method, CREAM (CorREction of Aerodynamic Matrices), uses surface pressure distributions obtained using computational fluid dynamics (CFD) simulations for the correction. It is based on a Taylor expansion of the aerodynamic influence coefficient matrix, where the Taylor coefficients are corrected successively. The approach can be applied to quasi-steady as well as to unsteady aerodynamic calculations. The method is demonstrated on the AGARD LANN wing at transonic attached flow conditions and compared to linearized unsteady CFD computations. Two different correction orders are examined: a “zeroth order correction” with a quasi-steady CFD sample as correction input and a “first order correction” with an additional unsteady CFD sample. It is shown that CREAM gives improved results for small reduced frequencies, where the first-order correction is always superior to the zeroth order correction.
PubDate: 2014-12-01

• Vortical flow prediction for the design of a wind tunnel experiment with a
pitching lambda wing
• Abstract: Abstract The IWEX wind tunnel model (Instationäres Wirbelexperiment, German for: Unsteady Vortex Experiment) was developed to study vortical flow at static and oscillating angles of attack. Numerical computations were performed beforehand to study important aerodynamic aspects. The focus of this paper is on those results that were affecting the design of the model. The experimental concept of a new test rig, wind tunnel walls and the new half wing model is briefly described. The lambda wing has a purely round leading edge with a constant nose radius to chord ratio of 0.5 %. The flow characteristics of the main vortex, generated at the nose of the main wing, and the smaller tip vortex are specified. The inboard motion of the main vortex with increasing angle of attack and the consequences for the load distribution are described. The free stream Mach number range of the test envelope is from 0.3 to 0.7. Therefore, transonic effects, especially shock–vortex interactions triggering vortex development, had to be analyzed for a safe design of the model. A peniche was designed to minimize the differences of the flow character compared to reference results of the model without wind tunnel walls. The effects of corner separation and displacement are specified at different stages of the iterative process. Finally, basic results for a pitching motion are discussed, based on global and distributed coefficients.
PubDate: 2014-12-01

• Model order reduction for steady aerodynamics of high-lift configurations
• Abstract: Abstract In aerodynamic applications, many model reduction methods use proper orthogonal decomposition (POD). In this work, a POD-based method, called missing point estimation (MPE), is modified and applied to steady-state flows with variation of the angle of attack. The main idea of MPE is to select a subset of the computational grid points (control volumes) and to limit the governing equations to this subset. Subsequently, the limited equations are projected onto the POD subspace. This approach has the advantage that the nonlinear right-hand side of the governing equations has to be evaluated only for a small number of points (control volumes) in contrast to POD, for which the full right-hand side has to be evaluated. An error estimation for MPE in the continuous ODE setting is tackled. Numerical results are presented for the Navier–Stokes equations for two different industrially relevant, two-element high-lift airfoils, one which is normally adopted during landing and the other during take-off.
PubDate: 2014-12-01

• Semi-empirical modeling of fuselage–rotor interference for
comprehensive codes: the fundamental model
• Abstract: Abstract The flow field around the isolated HART II fuselage is computed by a computational fluid dynamics code. Velocities normal to the rotor rotational plane are extracted in a volume around the rotor as a data basis. A simple semi-empirical analytical formulation of the fuselage-induced velocities, based on parameter identification from computational fluid dynamics or measured data, is developed for use in comprehensive rotor codes. This model allows the computation of fuselage–rotor interferences on the rotor blade element level. It also allows the prediction of the rotor wake geometry deformation due to the presence of the fuselage in both prescribed wake and free-wake codes. Its impact on rotor thrust, power and trim is evaluated analytically using blade element momentum theory and by DLR’s comprehensive rotor code.
PubDate: 2014-12-01

• Investigation and analysis of deterioration in high pressure compressors
due to operation
PubDate: 2014-12-01

• Development of a wind tunnel experiment for vortex dominated flow at a
pitching Lambda wing
• Abstract: Abstract A half wing model, a test rig and new wind tunnel walls were designed to study the vortex development at a lambda wing. The model has a sweep angle of 53° and a round leading edge. It is designed for pitching oscillations around a mean angle of attack of up to 20° up to a free stream Mach number of 0.7. Unsteady aerodynamic load data shall be delivered for aeroelastic simulations of Unmanned Combat Aerial Vehicles. Due to the highly nonlinear aerodynamic character, the design and sizing of the model had to take into account load cases with beginning and fully developed vortices. Furthermore, the different characters at subsonic and transonic speeds had to be included. Coupled simulations with a finite element model including the mounting and the connection to the actuation system were performed to assess the stability and the dynamic response of the model. Furthermore, the test concept and the process of the design of the model will be described.
PubDate: 2014-12-01

• SFB 880: aeroacoustic research for low noise take-off and landing
• Abstract: Abstract This paper gives an overview about prediction capabilities and the development of noise reduction technologies appropriate to reduce high lift noise and propeller noise radiation for future low noise transport aircraft with short take-off and landing capabilities. The work is embedded in the collaborative research centre SFB 880 in Braunschweig, Germany. Results are presented from all the acoustics related projects of SFB 880 which cover the aeroacoustic simulation of the effect of flow permeable materials, the characterization, development, manufacturing and operation of (porous) materials especially tailored to aeroacoustics, new propeller arrangements for minimum exterior noise due to acoustic shielding as well as the prediction of vibration excitation of aircraft structures, reduced by porous materials.
PubDate: 2014-12-01

• Comparison of real-time flight loads estimation methods
• Abstract: Abstract Nowadays flight load exceedance monitoring is an important task to both: the aircraft manufacturer as well as the operator. The estimation of flight loads is required in several phases during development and operation of an aircraft. The requirements are usually different, for e.g. calculation of design loads for certification and operational loads monitoring of stress and fatigue. The ability to determine aircraft operational loads (more) precisely may reduce the time in maintenance. Being able to detect critical load exceedance events during flight or in a post-process is also an enabler for e.g. loads/fatigue monitoring at operator level. In this paper, a novel system identification method named local model networks is applied to the field of flight loads estimation and compared to approaches based on artificial neural networks as found in the literature. The presented approach tries to overcome some limitations with respect to model creation, robustness, inter- and extrapolation.
PubDate: 2014-12-01

• Revised approach procedures to support optimal descents into Malta
International Airport
• Abstract: Abstract This paper presents a proposal for new approach procedures for the most commonly used runways at Malta International Airport, runways 31 and 13, as a basis to facilitate the introduction of optimal descents in Maltese airspace. In addition, a standard arrival, one from the north from where the large majority of aircraft approach Malta, linking to runway 31 is proposed. The design, following ICAO recommendations, is described in detail. Current practice of aircraft inbound from the same entry point, observed using ADS-B recorded data, is also presented in a discussion leading to the identification of gains that could result from flying the proposed arrival and approach routes optimally.
PubDate: 2014-12-01

• Design and aeroelastic assessment of a forward-swept wing aircraft
• Abstract: Abstract Aeroelastic effects strongly influence the design of an aircraft. To be able to assess those effects early on, reliable simulation models representing the global aeroelastic properties of a new design are required. At a conceptual or a pre-design stage, an intelligent parameterization concept allows for limited changes of the configuration while the simulation models are adapted accordingly. In the DLR project Integrated Green Aircraft, the goal was to investigate the impact of technologies for the reduction of fuel consumption on the aeroelastic properties of aircraft. One main aspect was the influence of laminar wing design on divergence, flutter and dynamic loads. As the reference aircraft in the project, the concept of a forward-swept wing aircraft with rear-mounted engines has been analysed. An aeroelastic model has been built up in the project. The model design procedure is based on the DLR in-house tool set MONA (ModGen/NASTRAN). Focus of this design process is the generation of a parameterized structural model, representing the global dynamic properties of the elastic aircraft, but as detailed as reasonable to capture relevant local effects and to result in a feasible structural design. In the article, the aircraft design is presented. The modelling and sizing process for the structure is described. Results of the loads analysis as well as of the aeroelastic stability analyses are discussed.
PubDate: 2014-12-01

• Assessment of leading-edge devices for stall delay on an airfoil with
active circulation control
• Abstract: Abstract The use of active, internally blown high-lift flaps causes the reduction of the stall angle of attack, because of the strong suction peak generated at the leading-edge. This problem is usually addressed by employing movable leading-edge devices, which improve the pressure distribution, increase the stall angle of attack, and also enhance the maximum lift coefficient. Classical leading-edge devices are the hinged droop nose or the more effective slat with a gap. The flow distortions generated by the gap become an important source of noise during approach and landing phases. Based on these considerations, the present work aims at evaluating the potentials of gap-less droop nose devices designed for improving the aerodynamics of airfoils with active high lift. Both conventional leading-edge flaps and flexible droop noses are investigated. Flexible droop nose configurations are obtained by smoothly morphing the baseline leading-edge shape. Increasing the stall angle of attack and reducing the power required by the active high-lift system are the main objectives. The sensitivities of the investigated geometries are described, as well as the physical phenomena that rule the aerodynamic performance. The most promising droop nose configurations are compared with a conventional slat device as well as with the clean leading-edge. The response of the different configurations to different blowing rates and angles of attack are compared and the stalling mechanisms are analyzed.
PubDate: 2014-12-01

• Hybrid structures in aero engines
• Abstract: Abstract The continuous increase in already high specific performance of aero engines and growing optimization demands require further innovation in the fields of materials and design of structures to reach the primarily aerodynamic driven goals. In general, the improvement of materials on its own cannot guarantee success but rather the combination of different materials offers the potential for increased performance and additional functionality. For using different material properties, an adapted hybrid design is necessary. Within this design outstanding material characteristics should be addressed, whilst the lower performance properties must not be critical and provoke faults. By combining different materials within hybrid structures, the feasible increase in performance is accompanied with the challenges of handling a lot more parameters for optimization. Three examples are described in this paper, showing hybrid design approaches for aero engine structures. The design principles can be transferred to similar structures by using the shown basic mechanisms. The first example covers a hybrid ring structure used for simultaneous movement of stator vanes within an axial compressor. BLISK technology with high aerodynamic efficiency and low structural damping requires an accurate positioning of the stator vanes to avoid dynamic excitation in transient surroundings during a complete flight cycle. Additionally, the weight of the structure should be reduced compared to conventional in-service structures. A second example shows a hybrid fan blade. Here it is demonstrated how titanium can be combined with carbon fibre-reinforced plastics to create an airfoil. This concept can be implemented in generating stator vanes and rotor blades for aero engines. A special surface treatment leads to a non-aging jointbetween the two materials. The third example explains the basics for an alternative hybrid rotor design. Three titanium rotor segments are joined together by brazing under vacuum conditions. During the manufacturing process, the inner areas of the rotor are accessible which offers the opportunity to integrate cavities as well as fibre reinforcement.
PubDate: 2014-11-28

• Multidisciplinary pre-design of supersonic aircraft
• Abstract: Abstract Forecasts predict a strong market for supersonic travel in the business sector. It is especially appealing for high-net-worth individuals because of both, the reduction of travel time and prestige. The ecological and economic challenges that are related to supersonic flight need adequate answers in terms of technology and tools to evaluate aircraft for the described task. This paper gives a short overview on research that has been conducted in the past, followed by the presentation of the work done by the authors. The integration of methods for the evaluation of supersonic business jets in the context of aircraft conceptual design is outlined. The determination of aerodynamic coefficients and loads is done by solving the inviscid Euler equations. Furthermore the propulsion module is extended and a mission analysis tool, which is used for fuel mass estimation is briefly explained. The methods for structural analysis are detailed. At the end the verification based on a reference configuration is described.
PubDate: 2014-11-27

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