Improving the performance of aeroacoustic measurements beneath a turbulent boundary layer in a wake flow

Experimental measurement and subsequent numerical prediction of the excitation of at plates or car windows beneath a turbulent boundary layer have become important for the development of novel cars and airplanes. A wavenumber spectrum can be used to define the load on a plat caused by the pressure fluctuations on the surface. Wavenumber spectra from measurements are used to validate the numerical predictions of the acoustic and hydrodynamic portions of the pressure fluctuations. When measuring wavenumber spectra, the design of the experiment can have a large in fluence on the outcome. In this paper, the effects of both array design and the application of deconvolution algorithms on the experimental determination of the wavenumber-frequency spectrum are evaluated

Application of SNGR Method to Compute Aero-Vibro-Acoustics of Heavy-Duty Rear-View Mirrors

Flow-induced noise inside cab interior (also termed aerodynamics-induced interior noise) is nowadays perceived as a key factor when assessing the quality of heavy-duty vehicles. In order to satisfy the turnaround time required for current product development, a simplified hybrid numerical approach has been adopted. It couples the SNGR (Stochastic Noise Generation and Radiation) method with a finite element method. The SNGR approach uses RANS (Reynolds Averaged Navier Stokes) for fast CFD (Computational Fluid Dynamics) computations, and is based on a stochastic model to synthesize turbulent velocity fluctuations. These fluctuations are then used to reconstruct aeroacoustic sources based on lighthill\u27s equation. Several rear-view mirror configurations have been chosen to validate this numerical approach. The results are in good agreement with the experiments performed on track. The numerical approach is finally demonstrated as a fast method that can be applied to assess and rank early designs in a short time for the purpose of reducing aerodynamics-induced interior noise