Numerical and experimental analysis of automotive turbocharger compressor aeroacoustics at different operating conditions

Highlights: • Three operating points of a turbocharger compressor are simulated using URANS and DES. • In-duct pressure signals are measured in a steady flow rig with three-sensor arrays. • Numerical and experimental pressure spectra are compared. • Near best efficiency point, boundary layer oscillates at high frequency. • Near surge, rotating stall produces whoosh noise. - Abstract: Centrifugal compressor aeroacoustics are analyzed by means of a three-dimensional CFD model. Three operating points at nominal compressor speed are simulated ranging from best efficiency point to near-surge conditions. Experimental measurements are obtained using a steady flow rig mounted on an anechoic chamber. URANS and DES predictions of compressor global variables and pressure spectra are compared against experimental measurements. Flow-induced noise increases as the operating point moves toward surge line. Stall at the suction side of the blades exists even for high mass flow conditions, causing a high frequency boundary layer oscillation. Low momentum cells rotating at the diffuser are found at points closer to surge, causing the so-called whoosh noise. Inducer rotating stall is also present at these conditions. Point closest to surge shows a rotating tornado-type vortex at the inducer, determining a moving low pressure region that increases low frequency noise content.