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  Subjects -> AERONAUTICS AND SPACE FLIGHT (Total: 96 journals)
Acta Astronautica     Hybrid Journal   (Followers: 211)
Advances in Aerospace Engineering     Open Access   (Followers: 2)
Advances in Space Research     Full-text available via subscription   (Followers: 232)
Aeronautica     Open Access   (Followers: 7)
Aerospace     Open Access   (Followers: 9)
Aerospace and Electronic Systems, IEEE Transactions on     Hybrid Journal   (Followers: 95)
Aerospace Science and Technology     Hybrid Journal   (Followers: 258)
Affective Computing, IEEE Transactions on     Hybrid Journal   (Followers: 10)
AIAA Journal     Full-text available via subscription   (Followers: 481)
Air Force Magazine     Full-text available via subscription   (Followers: 4)
Air Medical Journal     Hybrid Journal   (Followers: 3)
Aircraft Engineering and Aerospace Technology     Hybrid Journal   (Followers: 108)
American Journal of Space Science     Open Access   (Followers: 38)
Annual of Navigation     Open Access   (Followers: 2)
Artificial Satellites     Open Access   (Followers: 14)
ASTRA Proceedings     Open Access  
Aviation     Hybrid Journal   (Followers: 6)
Aviation in Focus - Journal of Aeronautical Sciences     Open Access   (Followers: 3)
Aviation Psychology and Applied Human Factors     Hybrid Journal   (Followers: 9)
Aviation Week     Full-text available via subscription   (Followers: 21)
Aviation, Space, and Environmental Medicine     Full-text available via subscription   (Followers: 6)
Canadian Aeronautics and Space Journal     Full-text available via subscription   (Followers: 20)
CEAS Aeronautical Journal     Hybrid Journal   (Followers: 25)
Chinese Journal of Aeronautics     Open Access   (Followers: 12)
Control Systems     Hybrid Journal   (Followers: 26)
Cosmic Research     Hybrid Journal   (Followers: 2)
COSPAR Colloquia Series     Full-text available via subscription   (Followers: 1)
Egyptian Journal of Remote Sensing and Space Science     Open Access   (Followers: 5)
Elsevier Astrodynamics Series     Full-text available via subscription   (Followers: 1)
Fatigue of Aircraft Structures     Open Access   (Followers: 7)
Frontiers in Aerospace Engineering     Open Access   (Followers: 6)
Frontiers in Astronomy and Space Sciences     Open Access  
Gyroscopy and Navigation     Hybrid Journal   (Followers: 112)
IEEE Aerospace and Electronic Systems Magazine     Full-text available via subscription   (Followers: 46)
IEEE Transactions on Circuits and Systems I: Regular Papers     Hybrid Journal   (Followers: 12)
International Journal of Aeroacoustics     Full-text available via subscription   (Followers: 6)
International Journal of Aerodynamics     Hybrid Journal   (Followers: 11)
International Journal of Aerospace Engineering     Open Access   (Followers: 45)
International Journal of Aerospace Innovations     Full-text available via subscription   (Followers: 12)
International Journal of Aerospace Sciences     Open Access   (Followers: 17)
International Journal of Applied Geospatial Research     Hybrid Journal   (Followers: 4)
International Journal of Aviation Management     Hybrid Journal   (Followers: 3)
International Journal of Aviation Psychology     Hybrid Journal   (Followers: 6)
International Journal of Aviation Technology, Engineering and Management     Full-text available via subscription   (Followers: 1)
International Journal of Crashworthiness     Hybrid Journal   (Followers: 5)
International Journal of Flow Control     Full-text available via subscription   (Followers: 4)
International Journal of Hypersonics     Full-text available via subscription   (Followers: 3)
International Journal of Micro Air Vehicles     Full-text available via subscription   (Followers: 4)
International Journal of Satellite Communications Policy and Management     Hybrid Journal  
International Journal of Space Science and Engineering     Hybrid Journal   (Followers: 2)
International Journal of Space Structures     Full-text available via subscription   (Followers: 3)
International Journal of Space Technology Management and Innovation     Full-text available via subscription   (Followers: 3)
International Journal of Sustainable Aviation     Hybrid Journal  
International Journal of Turbo & Jet-Engines     Hybrid Journal   (Followers: 1)
Journal of Aeronautical Materials     Open Access   (Followers: 1)
Journal of Aeronautics & Aerospace Engineering     Open Access   (Followers: 1)
Journal of Aerospace Engineering     Full-text available via subscription   (Followers: 51)
Journal of Aerospace Engineering & Technology     Full-text available via subscription   (Followers: 1)
Journal of Aerospace Information Systems     Full-text available via subscription   (Followers: 1)
Journal of Aerospace Technology and Management     Open Access   (Followers: 2)
Journal of Aircraft     Full-text available via subscription   (Followers: 165)
Journal of Airline and Airport Management     Open Access   (Followers: 5)
Journal of Astrobiology & Outreach     Open Access  
Journal of Aviation Technology and Engineering     Open Access   (Followers: 8)
Journal of Guidance, Control, and Dynamics     Full-text available via subscription   (Followers: 93)
Journal of Konbin     Open Access  
Journal of Navigation     Hybrid Journal   (Followers: 113)
Journal of Propulsion and Power     Full-text available via subscription   (Followers: 169)
Journal of Space Weather and Space Climate     Open Access   (Followers: 4)
Journal of Spacecraft and Rockets     Full-text available via subscription   (Followers: 281)
Journal of Spatial Science     Hybrid Journal   (Followers: 1)
Journal of the American Helicopter Society     Full-text available via subscription   (Followers: 1)
Journal of the Astronautical Sciences     Hybrid Journal   (Followers: 2)
Life Sciences in Space Research     Hybrid Journal  
Microgravity Science and Technology     Hybrid Journal  
New Space     Hybrid Journal   (Followers: 2)
Nonlinear Dynamics     Hybrid Journal   (Followers: 5)
Population Space and Place     Hybrid Journal   (Followers: 2)
Proceedings of the Human Factors and Ergonomics Society Annual Meeting     Hybrid Journal   (Followers: 6)
Proceedings of the Institution of Mechanical Engineers Part G: Journal of Aerospace Engineering     Hybrid Journal   (Followers: 28)
Progress in Aerospace Sciences     Full-text available via subscription   (Followers: 52)
Propulsion and Power Research     Open Access   (Followers: 4)
Recent Patents on Space Technology     Full-text available via subscription  
Research & Reviews : Journal of Space Science & Technology     Full-text available via subscription   (Followers: 1)
Russian Aeronautics (Iz VUZ)     Hybrid Journal   (Followers: 19)
Space and Polity     Hybrid Journal   (Followers: 2)
Space Policy     Hybrid Journal   (Followers: 16)
Space Research Today     Full-text available via subscription   (Followers: 27)
Space Safety Magazine     Free   (Followers: 4)
Space Science Reviews     Hybrid Journal   (Followers: 14)
SpaceNews     Free   (Followers: 173)
Transport and Aerospace Engineering     Full-text available via subscription   (Followers: 1)
Transportmetrica A : Transport Science     Hybrid Journal   (Followers: 2)
Unmanned Systems     Hybrid Journal  
Вісник Національного Авіаційного Університету     Open Access   (Followers: 1)
Вестник УГАТУ     Open Access  
Journal Cover   CEAS Aeronautical Journal
  [25 followers]  Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 1869-5582
   Published by Springer-Verlag Homepage  [2281 journals]
  • Multidisciplinary wing optimization of commercial aircraft with
           consideration of static aeroelasticity
    • Abstract: Abstract This article presents the development and application of a high-fidelity simulation process chain for commercial aircraft wing multidisciplinary optimization. Based upon a parametric CAD model the aerodynamic coefficients of the wing are determined through solving the Reynolds-averaged Navier–Stokes equations within a numerical flow simulation. Structural mass and elastic characteristics of the wing are determined from structural sizing of the wing box for essential load cases by usage of the finite element method. The interactions between the aerodynamic forces and the structural deformation of the elastic wing are taken into account in the process chain by fluid-structure coupling. To reduce the number of design variables, the design task is solved by a two-step approach. To design the inner wing, an optimization of the inner airfoil geometry and the wing twist with the lift-to-drag ratio as objective function has been conducted in the first step. Based on the inboard airfoil of this optimized inner wing, multidisciplinary optimizations of the wing planform have been performed in the second step. These optimizations include the wing twist and thickness distribution in span direction as design parameters but maintain airfoil shapes. A deterministic optimization method has been applied to locate the optimum within the design space. Range and efficiency, in terms of fuel consumption per range and payload, were used as objective functions in the wing planform multidisciplinary optimizations. Two approaches for the determination of the aerodynamic loads for the 2.5-g maneuver load case based on the aerodynamic loads under cruise flight conditions have been investigated. Both approaches have been integrated in the process chain for multidisciplinary wing optimization and have been used for the wing optimization of a long-range aircraft with backward swept wings. The results of the corresponding wing optimizations have been compared with each other.
      PubDate: 2015-09-01
       
  • Reduced order modelling for static and dynamic aeroelastic predictions
           with multidisciplinary approach
    • Abstract: Abstract We implement reduced order modelling techniques for aeroelastic predictions of the HIRENASD and S4T wings in order to represent CFD based high-fidelity solutions efficiently. Model reduction techniques such as non-intrusive Polynomial Chaos Expansion and Proper Orthogonal Decomposition are applied to both static and dynamic aeroelastic cases. The high-fidelity solutions are obtained by fluid structure interaction analysis using a 3D Euler unsteady aerodynamic solver and structural modal solution from a finite element solver. The model order reduction strategy is based on a multidisciplinary approach since both structural and aerodynamic input parameters are employed. The model order reduction is performed not only to represent the high-fidelity computational analyses when small variations of input parameters are considered but also to characterize the flutter responses of the S4T wing in a broad range of input values over the entire flight regime for Mach numbers between 0.60 and 1.20. The efficient aeroelastic analyses performed using the developed reduced order models agreed well with the high-fidelity computational analyses.
      PubDate: 2015-09-01
       
  • Model validation and analysis using feedforward control flight test data
    • Abstract: Abstract The German Aerospace Center (DLR) operates the ACT/FHS research helicopter with a full model-based control system applicable from hover to 120 knots forward flight, including take-off and landing. The feedforward controller used in this system is based on linear model inversion of identified local models. Therefore, the overall performance of the feedforward controller is highly dependent on the accuracy of the used inverted models. While several approaches exist to analyze model accuracy in time and frequency domains, a validation method for inverse models is rarely considered in the literature. In this paper, a flight test campaign that has been conducted to analyze model validity of the feedforward controller is presented and evaluated. A new model validation method using the feedforward controller to follow a reference command is discussed. Measured deviations from the commanded references are evaluated in the time domain to highlight the model subsystems that are not precisely represented by the linear models. The obtained results are compared with a validation method from system identification. Model extensions are proposed to increase the model accuracy for feedforward controller usage.
      PubDate: 2015-09-01
       
  • Comparing different approaches for modeling the vertical motion of the
           EC 135
    • Abstract: Abstract Helicopters like the EC 135 with its bearingless main rotor design feature large equivalent hinge offsets of about 10 %, significantly higher than conventional rotor designs and leading to improved maneuverability and agility. For such a helicopter, the fuselage and rotor responses become fully coupled and the quasi-steady assumption using a 6-DoF rigid-body model state space description and approximating the neglected rotor degrees of freedom by equivalent time delays is not suitable. Depending on the intended use of the model, the accurate mathematical description of the vertical motion for these configurations requires an extended model structure that includes inflow and coning dynamics. The paper first presents different modeling approaches and their relationship. Next, identification results for the DLR EC 135 are presented for a model that only describes the vertical motion excluding coupling to the other axes. Here, the differences between the modeling approaches and the respective deficits are explained. Next, the modeling approach most widely used in the rotorcraft identification literature is extended to account for hinge offset. In addition, some model parameters are estimated instead of fixing them at their theoretical predictions which leads to a very good match with EC 135 flight test data. Results for a complete model of the EC 135 including flapping, coning/inflow, and regressive lead–lag are shown as a final result.
      PubDate: 2015-09-01
       
  • Experimental investigation of turbulent boundary layers over transversal
           moving surfaces
    • Abstract: Abstract The influence of a spanwise traveling transversal surface wave on the near-wall flow field of turbulent boundary layers is investigated by particle-image velocimetry (PIV) and micro-particle tracking velocimetry (μ-PTV). The experimental setup consists of a flat plate equipped with an insert to generate a transversal spanwise traveling wave of an aluminum surface. PIV and μ-PTV measurements are conducted for three Reynolds numbers based on the freestream velocity and momentum thickness immediately downstream of the actuated surface Re θ  = 1200, 1660, and 2080. The transversal traveling wave is generated by a newly developed electromagnetic actuator system underneath the aluminum surface. Three amplitudes A = 0.25, 0.30, and 0.375 mm at a wave length of \(\lambda \, = \,160\,{\text{mm}}\) and a frequency of f = 81 Hz are investigated. The detailed analysis of the velocity profile shows the transversal traveling surface motion to redistribute the velocity in the viscous sublayer and in the logarithmic region of the turbulent boundary layer. The streamwise and wall-normal velocity fluctuations in the outer boundary layer are increased and the streamwise momentum in the near-wall regime is lowered. The drag reduction ratio (DR) due to the actuation is determined by the velocity gradient in the viscous sublayer. At the lowest Reynolds number the drag-reducing impact is proportional to the amplitude of the wave. That is, the higher the amplitude, the more pronounced the drag reduction resulting in a friction drag reduction up to 3.4 % compared to the non-actuated configuration.
      PubDate: 2015-09-01
       
  • PACS: numerical approach and evaluation of a concept for dimensioning
           pressure-actuated cellular structures
    • Abstract: Abstract A biologically inspired concept is investigated which can be utilized to develop energy efficient, and lightweight adaptive structures for various applications. Summarizing basic demands and barriers regarding shape-changing structures, the basic challenges of designing morphing structures are listed. The analytical background describing the physical mechanisms of PACS is presented in detail. This work focuses on the numerical approach of calculating the geometrically, highly nonlinear deformation states of pressure-actuated cellular structures. Beyond the calculation of equilibrium states, a form-finding algorithm is presented, which allows determining structural designs following predefined target shapes. Initially made assumptions are dropped incrementally to show the effects on the accuracy of the modeling. Finite element method-based calculations and experimental test results provide the computational target data for the varying grade of simplifications. Representative of more complex structures, like aircraft control surfaces, the examined geometries are chosen to evaluate the generic numerical methods and to validate the functionality of the basic working principle.
      PubDate: 2015-08-23
       
  • Semi-empirical modeling of fuselage–rotor interference for
           comprehensive codes: influence of angle of attack
    • Abstract: Abstract The flow field around the isolated Bo105 fuselage including the tail boom and empennage is computed by an unsteady panel code. Velocities normal to the rotor rotational plane are extracted in a volume around the rotor as a data base. A simple semi-empirical analytical formulation of the fuselage-induced velocities, based on parameter estimation from the panel code data, is extended to include rotor shaft angles of attack from \(\alpha =-90^{\circ }\) (hover, vertical climb) to +90° (vertical descent) for use in comprehensive rotor codes. This model allows the computation of fuselage–rotor interferences on the rotor blade element level in a simplified form, thus eliminating the need for costly CFD computation (of this effect). 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 estimated analytically using blade element momentum theory.
      PubDate: 2015-08-18
       
  • Investigation into the effects of fiber waviness in standard notched
           composite specimens
    • Abstract: Abstract This study presents a numerical and experimental evaluation of the standardized material testing specimens (tension and compression) used for determining the strength of composite materials in the presence of defects. The composite specimens contain through the thickness fiber waviness and a circular cutout. The intentional waviness levels have been applied in the out-of-plane direction of the multi and unidirectional laminate during the curing process. The standardized face-stabilized open-hole compression test based on ASTM D6484 and the open-hole tension test according to ASTM D5766 are used for evaluating the interaction of the fiber waviness and the circular cutouts. Temporal evaluations of the load-deformation response in the specimens are coupled with optical microscopy to understand the failure modes and damage progression. Laminates with multidirectional layups show different failure modes and a different damage trajectory when compared with the response in the unidirectional laminates. The damage trajectory is dominated by the notch region and also influenced by notch size and free edge effects.
      PubDate: 2015-08-15
       
  • Sensor fusion and flight path reconstruction of the ACT/FHS rotorcraft
    • Abstract: Abstract DLR’s active control technology/flying helicopter simulator (ACT/FHS) research rotorcraft supports research in a variety of fields. This paper presents the flight path reconstruction (FPR) of the ACT/FHS for post-flight data processing and its online sensor fusion during flight. Both are fundamental for system identification and flight control research. First, the ACT/FHS rotorcraft, its system architecture and the used sensor instrumentation are described. Then, the implemented unscented and extended Kalman filters are briefly explained and the applied kinematic and measurement models of the FPR are introduced. The wind estimation performance of the FPR is evaluated using simulation and flight test data accordingly. Subsequently, the online sensor fusion is motivated and its behaviour following a simulated differential GPS failure is analysed and explained.
      PubDate: 2015-08-08
       
  • Helicopter emergency medical service: motivation for focused research
    • Abstract: Abstract Since the early helicopter developments, there has been tremendous progress in performance, handling qualities, comfort and efficiency. This is why helicopters have conquered their niche in the aircraft market despite their very limited capabilities in terms of maximum speed and range or fuel efficiency, especially when compared with modern fixed wing aircraft. However, some features make helicopters very useful for many missions, which to date cannot be performed by any other contemporary series production aircraft. These features include their capability to hover, to climb or sink either vertically or almost vertically, to fly slowly in any horizontal direction (even backwards) and still maintain good handling qualities. When compared to other aircraft which are able to hover (e.g. tiltrotors or fixed wing vertical take-off and landing aircraft), they even show in that flight regime superior flight performances. These features allow helicopters to fly “nap of the earth” at low altitudes within an obstacle backdrop and land almost anywhere, even in confined areas (provided any obstacles do not present a threat level which is too high). These capabilities make helicopters prone not only to simply rescue people in distress (e.g. from mountains or ships in emergency situations), but also to provide full emergency medical service. This service is called helicopter emergency medical service (HEMS). No other aircraft is more suitable for such a service than helicopters. This is why many nations have established professional HEMS systems in their countries; ranging from young systems such as that adopted in Japan to the oldest one, located in Germany. This paper aims to first give an overview on some historical aspects on the development of HEMS. Secondly, it outlines HEMS Systems established in various nations like Germany, Switzerland, Japan, and the United States of America. Next the paper gives a short survey on statistical data on rescue helicopters and to some extent on noise aspects of helicopters in general. The latter topic will be discussed briefly, since noise problems are linked to all helicopters not just to rescue helicopters. Following this, some sobering facts on HEMS will be reviewed, more precisely the high number of accidents. Finally, the paper concludes with some remarks and gives a brief outlook on a research concept dubbed the “Rescue Helicopter 2030” which has been started recently at the Deutsches Zentrum für Luft- und Raumfahrt (DLR, German Aerospace Center).
      PubDate: 2015-08-08
       
  • New Orientation of the Editorial Board
    • PubDate: 2015-08-05
       
  • Compressor map computation based on 3D CFD analysis
    • Abstract: Abstract The focus of the paper is on procedures and strategies to compute high-fidelity compressor maps for aero engines based on 3D CFD. The developed automatic process starts with an operation point analysis where a convergence checker terminates the running 3D flow analysis as soon as physical quantities such as mass flow or aerodynamic blade row loss have converged. Subsequently, the corresponding compressor speed line is determined, where operation limits like surge and choke are detected by solving optimization and root search problems, respectively. Such speed lines also have to be calculated for various other shaft speeds to obtain the whole performance map. This is achieved by adjusting shaft speed and boundary conditions, where the mesh for variable stator vanes and the amount of bleed mass flow are adapted automatically according to given schedules. Finally, the developed process is applied to a 4.5-stage axial compressor to demonstrate feasibility of the proposed strategies.
      PubDate: 2015-07-25
       
  • Flap efficiency analysis for the SAGITTA diamond wing demonstrator
           configuration
    • Abstract: Abstract The efficiency of deflected midboard flaps is investigated on a diamond wing-shaped unmanned aerial vehicle, the SAGITTA demonstrator configuration. The Reynolds-Averaged Navier-Stokes equations are applied to compute numerical results for a variety of flight conditions with varying angle of attack, sideslip angle, and midboard flap deflection. Low-speed wind tunnel conditions are regarded to compare the results to existing experimental data. The focus is particularly laid on the analysis of the aerodynamic coefficients and derivatives in both the longitudinal and the lateral motion. The occurring flow phenomena are motivated and discussed by flow field illustrations that are available from the numerical computations. The results show at small to moderate angles of attack linear flap characteristics, since the overall flow field is dominated by attached flow. With increasing angle of attack and additional sideslip angle, however, the leading-edge vortex originating from the inboard sharp leading edge and the wing tip separation region affect the midboard flap efficiency. Non-linear coupling effects become obvious, which particularly affect the roll and pitch control effectiveness.
      PubDate: 2015-07-03
       
  • Simulation and validation of slat de-icing by an electromechanical system
    • Abstract: Abstract The Electro-Impulse De-Icing system is an alternative process of de-icing wing slat structures made of carbon fiber reinforced plastics or aluminum. It is especially qualified for no-bleed systems that are used in modern and future aircraft. Due to the time-dependent interactions between the induced magnetic field and the structural deformation it can be necessary to couple these physical fields in analyses. This paper presents a three-dimensional simulation as well as experiments of flat plates. The simulation is characterized by electrical and structural finite element calculations, which are two-way coupled in each time step. The current progress is based on real tests which are executed at a special test rig. A coil, which is connected to an impulse generator, is used to induce magnetic forces. Flat plates of aluminum or carbon fiber reinforced plastics (with an additional aluminum doubler) were tested at room temperature and deformation results were used to validate numerical simulations. Further research deals with the simulation of the de-icing process itself with a stress criterion for ice adhesion. Therefore, the test rig is mounted in a cooling chamber. The ice layer is produced by spraying cooled water through a nozzle with a droplet size of supercooled large droplets (SLD). The deformation progress with and without ice is analyzed at different impulse forces and ice thicknesses. The coupled finite element analysis gives the opportunity to simulate the process of de-icing in situ to the time-dependent loading of the plate by magnetic forces. Furthermore, the complex dynamic behavior of the structure can be simulated with excellent agreement to real tests.
      PubDate: 2015-06-01
       
  • 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: 2015-06-01
       
  • 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: 2015-06-01
       
  • 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: 2015-06-01
       
  • 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: 2015-06-01
       
  • A systems architecting framework for optimal distributed integrated
           modular avionics architectures
    • Abstract: Abstract This work presents a novel holistic framework for Distributed Integrated Modular Avionics (DIMA) architecture design and optimization. Integrated Modular Avionics (IMA) are a standardization of avionics components. IMA is beneficial in weight and costs if the complexity of sizing, function allocation, and topology selection is mastered. In preceding publications, stand-alone models and optimization algorithms were developed, which significantly support different aspects of DIMA architecture design. This article extends, integrates, and compares all methods in a holistic framework, which enables model and algorithm-aided design of avionics architectures. Domain-specific modeling of systems software, hardware, and aircraft anatomy enables automated verification and early evaluation of architectures. Moreover, the model is the foundation for a flexible kit of eight optimization routines. For design issues in which humans likely lose the overview optimization routines are proposed. The degree of freedom in optimization ranges from function mapping over routing to a complete architecture generation. Routines for platform selection, network, and topology optimization are unique and unrivaled today. All optimization problems are solved globally optimal and a multi-objective solving algorithm calculates the best trade-off architectures for contradicting objectives, the Pareto optimum. All optimization routines are extensively tested by designing the optimal DIMA architecture for aircraft system functions in an A320-like scenario. Results show significant optimization potential of generated architectures compared to a manually designed one. The resulting architectures are analyzed and compared in performance and structure in detail.
      PubDate: 2015-05-17
       
  • Collaborative understanding of disciplinary correlations using a
           low-fidelity physics-based aerospace toolkit
    • Abstract: Abstract When performing aircraft design, covering all relevant physical effects and mutual interactions at a sufficient level of fidelity necessitates simultaneous consideration of a large number of disciplines. This requires methods in which teams of engineers simultaneously apply both their analysis modules and knowledge to collaboratively approach design challenges. In the current work, recent technical advancements of the German Aerospace Center (DLR) in data and workflow management are utilised to establish a toolbox containing elementary disciplinary analysis modules. This toolbox is focused on providing fast overall aircraft design capabilities. The incorporated empirical and physics-based low-fidelity modules can be used for setting up modular design workflows, tailored for the considered design cases. This enables the involved engineers to identify design trends at low computational effort. Furthermore, areas of common physical affinity are identified among the engineers, serving as basis for communication. Clear visualisation methods aid in efficiently translating knowledge between the involved engineers within the identified areas of common affinity. In later phases of the design process, the gathered knowledge serves as basis for incorporating modules of higher fidelity. Two application cases guide the present work. In the first application case, a system-of-systems approach is established by applying the elementary aircraft design toolbox to generate requirement sets for engine preliminary design. In this way, a clear synergy is established between the design of both the airframe and power plant. In the second application case, the applicability of a strut-braced wing as potential short-to-medium-range aircraft is investigated by a team of engineers. Within both application cases, methods are applied in which the involved engineers share their knowledge through a collaborative design approach.
      PubDate: 2015-04-29
       
 
 
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