An Efficient Hybrid Computational Aeroacoustic Process: Validation and Applications for Vehicle Development

The implementation and application of numerical methodologies for aeroacoustic analysis becomes more and more essential for car manufacturers in order to optimize the effectiveness of vehicle development. In the present work, a hybrid numerical tool based on the combination of a delayed detached eddy simulation and a finite element model based on the Lighthill’s analogy and the acoustic perturbation equations is presented. The computational fluid dynamics (CFD) and the computational aeroacoustics (CAA) simulations are performed by the software OpenFOAM and Actran, respectively. The aeroacoustic behavior of the SUV Lamborghini Urus at a cruising speed of 140 km/h has been investigated. The aeroacoustic phenomena in the side mirror region are the main object of the analysis and the results are presented in a frequency range up to 2.5 kHz. In order to be able to validate the numerical simulations, measurements have been performed in the aeroacoustic wind tunnel of the University of Stuttgart, operated by FKFS. The CFD simulation has been validated by the analysis of the velocity field measured by cobra probes placed in the wake of the side mirror. The aeroacoustic predictions have been validated by a comparison of the predicted total pressure fluctuation with the experimental data of surface microphones installed on the side window. Furthermore, the simulated acoustic contribution to the pressure fluctuation, calculated by using the acoustic perturbation equations (APE), has been validated against exterior microphones and beamforming measurements. Both, the CFD and the CAA show convincing correlations to the wind tunnel experiments. Lastly, the interior noise propagation is investigated. A further computational step to calculate the sound pressure level transmission to the interior cabin is presented and the respective experimental approach is discussed. In addition, the results of a first part of the validation, carried out by performing a hammer shock test on the side window, are shown.