Sensitivity of compressor aerodynamic noise prediction to time setup of CFD simulations using hybrid CAA method

Abstract

This paper numerically studies the aerodynamic noise of a centrifugal compressor in a vehicle engine turbocharger. The hybrid CAA approach based on computational fluid dynamics (CFD) and acoustic boundary element method (BEM) in the prediction of aerodynamic noise is validated. The impacts of the time setup of unsteady CFD simulations on the prediction of compressor flow and aerodynamic noise are discussed. The results show that a large time step would result in unreliable numerical results, in which severe reverse flow and flow separation can be observed. The middle time step 2 deg. can get accurately predicted results while reducing the computational efforts. It is also found that a large total simulation time with a reasonable time step is helpful to improve predicted noise spectra. Moreover, the overall sound pressure level discrepancy of aerodynamic noise between numerical prediction and experimental measurement is less than 0.5 dB.