Whoosh noise measurements from an automotive centrifugal compressor

Abstract

Broadband noise, accompanying the flow separation and turbulence, is studied for an automotive centrifugal compressor on a steady-flow turbocharger bench facility. When operated in the mid-flow region, the current compressor exhibited elevated broadband noise at high frequencies, which was evident both in the upstream compressor duct and external sound pressure level (SPL) measurement locations. Viewing SPL data as a function of the flow angle relative to the leading edge of the inducer blades (incidence angle) reveals a relationship which is nearly independent of the rotational speed. As the incidence angle is increased, broadband noise levels first go up gradually, nearly level off, and then decrease sharply at a critical incidence angle.