Aeroacoustic Wind Tunnel Correction Based on Numerical Simulation

Kurzfassung

The thesis focuses on the numerical investigation of the free shear layer effects under various situations: the variation in the shear layer thickness, in the shear layer shape, in the flow speed, in the source frequency and in the flow type (averaged mean flow including non parallel flow effects or turbulent flow). In this way, a systematical and detailed analysis of the free shear layer effects is provided with the evaluation of the state of the art correction method (Amiet's apporach). Using a hybrid Computational AeroAcoustics method, the mean flow gradient effects and the turbulence effects were treated seperately to study their influences on both two-dimensional and three-dimensional sound propagation. These results offer insights into the variation of the shear layer effects with each parameter. The correction method (Amiet's approach) is proven to be efficient in 2D and specific 3D (planar shear layer)situations. The error due to the shear layer shape in 3D can be avoided by locating the microphones outside the aforementioned "dangerous area". The position of such a "dangerous area" is found to be related to the size of the nozzle geometry.