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Showing papers in "Aerospace Science and Technology in 1999"


Journal ArticleDOI
TL;DR: The chemistry of Ni-based superalloys designed for single crystal gas turbine blades has significantly evolved since the development of the first generation of alloys derived from columnar grained materials as mentioned in this paper.

415 citations


Journal ArticleDOI
TL;DR: Quality function deployment and its use in multi-objective control synthesis tuning and design assessment, with application to flight control design is described.

67 citations


Journal ArticleDOI
TL;DR: In this article, a nonlinear attitude model of a satellite with thrusters, gravity torquesers and a reaction wheel cluster is developed and a linearized version of this satellite attitude model is derived for the attitude hold mode.

61 citations


Journal ArticleDOI
TL;DR: In this paper, a simple approach which consists in applying the original H ∞ synthesis technique to a modified LPV system is proposed, where the attractive numerical properties of the initial algorithm are preserved and the proposed method suffers from the lack of rigorous theoretical justification.

58 citations


Journal ArticleDOI
TL;DR: In this article, a control design approach based on eigenstructure assignment by dynamic feedback is presented, which permits the designer to handle simultaneously robustness against real parameter variations (from a multimodel point of view) and the use of structured gain including, as a special case, scheduled gains.

50 citations


Journal ArticleDOI
TL;DR: In this paper, the authors evaluated the potential benefit of adding a four-port wave rotor to a gas turbine and found that almost all the engines under study benefit from the wave rotor addition and that the most significant gain is obtained for gas turbines for which the compressor pressure ratio is moderate (∼5) and the turbine inlet temperature is fairly high (> 1600 K).

48 citations


Journal ArticleDOI
TL;DR: Why the high visibility of the two input, two output command augmentation structure of TECS is an improvement over current flight control system architectures is described.

46 citations


Journal ArticleDOI
TL;DR: In this article, a parametric identification technique based on the conjugate gradient methods was used to identify a tubular and cylindrical "dumbbell" with different strain rates, from 10 −3 to 130 s −1, and for impact velocities ranging from 5 mm/min to 6 m/s.

44 citations


Journal ArticleDOI
TL;DR: In this article, the effects of stable stratification on aircraft wake vortices are investigated by means of high-resolution two-dimensional simulations, and it is shown that the prominant effects, deceleration, detrainment and acceleration, are caused by the kinematic interaction of the vorticity generated by baroclinity and the primary vortivity.

40 citations


Journal ArticleDOI
TL;DR: In this article, the fundamental natural frequency of a non-viscous and incompressible liquid has been determined for increasing width of an annular ring baffle attached to the tank wall.

39 citations


Journal ArticleDOI
TL;DR: The computational model building of such a multidisciplinary non-linear aircraft simulation model for the design and validation of flight control systems is described.

Journal ArticleDOI
TL;DR: In this article, the response of the liquid surface elevation above its equilibrium position, as well as the viscous liquid force in x-direction due to translational excitation in this direction have been numerically evaluated.

Journal ArticleDOI
TL;DR: In this paper, the fuel conversion efficiency behind the combustor of a JT9D-7A aircraft engine in flight has been simulated using an extended exhaust plume chemistry model.

Journal ArticleDOI
TL;DR: In this paper, the use of steady and unsteady tangential blowing to suppress the dynamic stall on an oscillating airfoil was studied by numerically solving the Reynolds averaged Navier-Stokes equations.

Journal ArticleDOI
F Köpp1
TL;DR: In this article, the authors used the DLR ground-based Doppler lidar for experimental investigations of wake vortices generated by military-type aircraft, including fixed-wing as well as rotor-wing aircraft.

Journal ArticleDOI
TL;DR: In this article, the authors investigated the origin of shock oscillations on an 18% thick biconvex aerofoil using a thin-layer Navier-Stokes code.

Journal ArticleDOI
TL;DR: In this paper, the impact-friction of the tip of a blade coated either with NiCoCrAlYTa alloy or with a Ni/BN-Al deposit and accelerated to high linear speeds (300-500 m/s) has been studied in high temperature gases (∼1000 ÂC) on NiCrFeMo super-alloy substrates coated with stabilized zirconia (8% at Y2O3).

Journal ArticleDOI
TL;DR: In this paper, an in-depth analysis of the network's inner parameters reveals some potential reasons for an immanent delay of pilot thrust-set responses in wind shear situations.

Journal ArticleDOI
TL;DR: In this article, a transient fast dynamic finite element method has been chosen for its potential to model the nonlinearities of the structure, geometrical, material or contact nonlinearity.

Journal ArticleDOI
TL;DR: The characterisation of the aeroshape selected for the X-38 [Crew Return Vehicle (CRV) demonstrator] is presently being performed as a co-operative endeavour between NASA, DLR (through its TETRA Program), and the European Space Agency (ESA) with Dassault Aviation integrating the aerodynamic and aerothermodynamic activities as mentioned in this paper.

Journal ArticleDOI
TL;DR: In this paper, a numerical procedure based on FE modelling and characterisation of material failure constitutive models is proposed in order to limit the experimental procedure, which can also resolve problems linked to limit-design or the design of new riveted joint assemblies more rapidly and cost effectively than experiments.

Journal ArticleDOI
TL;DR: An unique active sidestick concept based on the electro-magnetic actuation principle (electro- magnetic sidesticks, MAGSI) is presented and this system is the key element in DLR's research programme EPIAS (Enhanced Pilot Information by using Active Sidestick) which is scheduled to be flight tested on the ATTAS (Advanced Technologies Testing Aircraft System) in-flight simulator at the beginning of next year.

Journal ArticleDOI
TL;DR: In this article, the authors consider the few lowest vibrational levels of a CO 2 -N 2 mixture and the V-T and V-V energy transfer processes between these levels.

Journal ArticleDOI
TL;DR: In this paper, the authors extended the applicability of a crack length and hole size model developed previously for a normally impacted spacecraft wall to the case of obliquely incident particles, and compared with experimental data and the predictions of empirical hole size and crack length models.

Journal ArticleDOI
TL;DR: In this paper, the authors examined the control performance of an Open-Loop Control System in the frequency and time domain by computing the power density spectra of the vertical and the horizontal acceleration in geodetic co-ordinates.

Journal ArticleDOI
TL;DR: In this article, the authors emphasize the usefulness of the μ framework for the analysis of the robustness properties of flight control systems, and show that several classical problems (computation of a phase or delay margin, non-linear analysis of a PIO effect, computation of a frequency domain overshoot) can be extended to an uncertain aircraft model.

Journal ArticleDOI
TL;DR: In this paper, numerical simulations based on the two-dimensional vorticity-stream function formulation were used to investigate the behavior of wake vortices near the ground over a wide Reynolds number range and to determine the maximum height the primary vortex reach far downstream of the lifting wing.


Journal ArticleDOI
TL;DR: In this paper, a solar dynamic power system with a Stirling engine for space station application is described and its unsteady behaviour is theoretically modelled and numerically simulated for four representative orbit configurations.

Journal ArticleDOI
TL;DR: In this article, an Euler method (WAVES) developed by ONERA and coupled with a boundary layer code (MI3DI) is presented, validated and applied to compute the total performance of rotors with different tip shapes.