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Riehmer J.,German Institute of Aerodynamics and Flow Technology
DLR Deutsches Zentrum fur Luft- und Raumfahrt e.V. - Forschungsberichte | Year: 2015

The aim of this work was the design of a scramjet configuration with inlet, combustor and nozzle for a flight experiment on a sounding rocket and test of this configuration in the hypersonic wind tunnel (H2K) of the German Aerospace Center in Cologne. Therefore semi-empirical design methods, based on previous studies were used to define an optimized scramjet geometry. The performance parameters and the off-design behavior were determined in advance with extensive numerical simulations and were subsequently verified in the wind tunnel experiments. The experiments were carried out for the entire scramjet configuration under flight-related conditions, in which the combustion was simulated by the injection of high pressure air. In order to study the scramjet configuration's behavior at different flight conditions, the flow was varied in relation to Reynolds number, stagnation temperature, and angle of attack. Here, a stable supersonic flow was observed with Pitot measurements, wall pressure measurements, and infrared thermography, which confirmed the design methods.

Wild J.,German Aerospace Center | Wild J.,German Institute of Aerodynamics and Flow Technology
Journal of Aircraft | Year: 2013

Experimental investigations have been carried out with the two-dimensional DLR-F15 high-lift wing-section model in the Cryogenic Wind-tunnel Cologne DNW-KKK to differentiate between the influence of Mach and Reynolds numbers on the stall behavior. Because of the cryogenic environment, Mach and Reynolds numbers have been varied independently between M = 0.1-0.25 and Re = 1.4 × 106 - 15.6 × 106. The investigation covers two- and threeelement configurations at various slat and flap settings and two different slat shapes. The focus of the investigation is to identify conditions of turbulent leading-edge stall, shock-related lift limitations, and flap separations and their influence on achievable maximum lift coefficient. Copyright © 2013 by Jochen Wild, DLR Institute of Aerodynamics and Flow Technology.

Cummings R.M.,United States Air Force Academy | Schutte A.,German Aerospace Center | Schutte A.,German Institute of Aerodynamics and Flow Technology
Aerospace Science and Technology | Year: 2013

The numerical simulation of the flow for the VFE-2 delta wing configuration with rounded leading edges is presented using the Cobalt Navier-Stokes solver. Cobalt uses a cell-centered unstructured hybrid mesh approach, and several numerical results are presented for the steady RANS equations as well as for the unsteady DES and DDES hybrid approaches. Within this paper the focus is related to the dual primary vortex flow topology, especially the sensitivity of the flow to angle of attack and Reynolds number effects. Reasonable results are obtained with both steady RANS and SA-DDES simulations. The results are compared and verified by experimental data, including surface pressure and pressure sensitive paint results, and recommendations for improving future simulations are made. © 2011 Elsevier Masson SAS. All rights reserved.

Hepperle M.,German Aerospace Center | Hepperle M.,German Institute of Aerodynamics and Flow Technology
Journal of Aircraft | Year: 2010

Inverse design methods are elegant and efficient tools for the design of aerodynamic shapes like airfoils, wings, and propellers. In the case of propeller design, only a few general parameters have to be prescribed and the design procedure returns the propeller geometry in terms of chord-length and blade-angle distributions along the radius. The common design procedures require the prescription of the lift coefficient over the blade radiusin orderto obtain the unknown chord length. In this paper, a modified design method is presented that allows for designing optimum propellers having a prescribed chord-length distribution. Now the radial distribution of the lift coefficient becomes the unknown, which is determined by the design procedure. Copyright © 2010.

Dobrzynski W.,German Aerospace Center | Dobrzynski W.,German Institute of Aerodynamics and Flow Technology
Journal of Aircraft | Year: 2010

The most important findings from experimental and applied research in airframe noise worldwide are discussed. Efforts were undertaken to first quantify airframe noise through dedicated flyover noise measurements when airframe noise was identified as the potential lower aircraft noise barrier in approach. Fink developed the first semi-empirical airframe noise prediction method based on this approach. There are still other types of noise sources, which were detected lately when the first full-scale original airframe component tests were possible with the availability of large acoustic wind tunnels. Such noise tests were performed on original landing gears and an aircraft wing in high-lift configuration. When airframe noise was identified as a major aircraft noise component in approach scale model wind-tunnel experiments were conducted to quantify landing gear noise characteristics. The model of Smith and Chow computed sound intensities according to the components' dimensions and orientation with respect to an observer location.

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