Characteristics of Sound Sources of Pulsating Flow Induced Noise in a Muffler Cavity

Abstract

The flow-induced noise was experimentally studied for an expansion-cavity-type muffler with pulsating flow. The resonance noises of the cavity have already been found to have the contribution to the total flow-induced noise from the muffler with pulsating flow. The main sound source in a low-Mach-number flow is pressure fluctuation on the solid boundaries. The distribution of the sound source strength on the inner surface of the cavity was clarified through the correlation analysis between the pressure fluctuation on the inner surface and the radiated sound pressure. The results showed that the sound source strength attained maximum at the exit wall of the cavity, where the jet flow collided. The sound strength depends on both time derivative of the pressure on the surface and correlation area, in which the pressure fluctuation shows simultaneity. The characteristics of sound source were discussed considering the correlation area and the pressure fluctuation strength.