Aeroacoustic Measurements and Validations of Numerical Simulations for the Case of a Generic Vehicle Structure

The aim of the project Akusim (part of the German research network Quiet traffic) was the numerical simulation of the flow induced noise generation and the radiation with hybrid calculation methods. For this purpose a generic structure (semi-cylinder with triangular wedge) was defined. To validate the results of the numerical simulations, experimental measurements of the flow field as well as the sound field were carried out, which include hotwire measurements, measurements of the wall-pressure fluctuations as well as measurements of the acoustic far field pressure. The results of both measurements and the numerical simulations are compared. Depending on the test conditions (tripping of the boundary layer) the measured sound and flow field data exhibit two different resonances which also show up in two different numerical simulations. To examine the relation between the measured flow field data and sound field data, the correlation between wall pressure fluctuations and acoustic far field pressure was determined. The correlations also show two different resonances and their dependency on the test conditions