Abstract
The flow induced noise from simple expansion cavity type mufflers with pulsating flow was studied. Generation characteristics of the flow induced noise were compared between the cases with pulsating flow and steady flow. Main components of the flow induced noise from the muffler were found to be resonance noises of the cavity and tailpipe of the muffler with both steady and pulsating flow. The sound level of the tailpipe resonance was reduced with bellmouth at the entrance of the tailpipe. The sound level of the cavity resonance was reduced with bellmouth at the entrance of the cavity. The results showed that similar to the case with steady flow, the tailpipe resonance with pulsating flow was excited by the separation noise generated at the entrance of the tailpipe. Unlike the case with the steady flow, the cavity resonance was excited not only by the shear noise generated at the entrance of the cavity but also by the turbulence noise generated near the exit of the cavity.
