ZURUECK HOCH VOR INHALT SUCHEN

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Proposing Institution

Lehrstuhl für Aerodynamik, TU München
Project Manager

Prof. Dr.-Ing. habil. Christian Breitsamter
Boltzmannstr. 15
85748 Garching
Abstract
Several research activities are currently going on at the Chair of Aerodynamics and Fluid Mechanics (AER) of the Technical University of Munich (TUM). Related topics to the proposed project are turbulence model conditioning, delta wing and diamond wing aerodynamics and investigations on flexible wing structures. All these topics shall be investigated more thoroughly by extensive numerical computations. For so called delta- and diamond wing configurations the aerodynamic characteristics are mainly dominated by vortex structures. The exact formation of these vortices strongly depends on the geometric parameters of the configuration and the free stream conditions. The exact formation, the flow physics of the vortices and the influence on the overall flight dynamics are subject to current research activities at TUM-AER. In order to analyze the flow field of such aircraft configurations, time-accurate CFD computations have to be conducted to determine the unsteady flow phenomena. Focusing on vortex dominated flows, related to delta wings, (U)RANS numerical simulation with eddy viscosity models (Spalart-Allmaras, k-ω) is an appropriate tool with respect to the computational effort but higher accuracy is required; the major inaccuracies are due to the vortical flow. More complex turbulence models like RSM (Reynolds Stress Models) introduce stability issues and increase the computational cost, not always improving the flow solution; DES and LES models, on the other hand, are much more expensive in term of computational cost. The idea to enhance the Spalart-Allmaras one-equation eddy viscosity model is introduced in order to improve the accuracy. The vortex topology is adjusted by correcting the distribution of eddy viscosity. Experimental data, i.e. pressure distribution and integral forces, are used as reference to automatically optimize the coefficients of the additional terms of the Spalart-Allmaras turbulence model for the considered flow case. In the context of aircraft vertical flow, active and passive flow control on vortex-dominated aircraft shall be investigated in more detail by means of numerical investigations. This includes possible manipulation methods (active and passive flow control) of the vortex bursting mechanism, which purpose to improve the post stall behavior. Additionally, the directional and dynamic stability is affected by the vortex dominated flow. The presence of the leading-edge vortices lead to strong non-linear aerodynamic characteristics of the flight vehicle and decreased controllability. Flow control devices to ensure stability and controllability of such configuration shall be investigated numerically and are validated by available experimental data.

Impressum, Conny Wendler