Analytical and experimental aeroacoustic studies of open-ended three-duct perforated elements used in mufflers

Abstract

Perforated element mufflers have been known to have good acoustic performance, when used on automotive exhaust systems. In the last decade and a half, plug mufflers, concentric hole resonators, and three-duct closed-end perforated elements have been studied. The present investigation concerns open-ended, three-duct perforated elements, which are known to combine high acoustic transmission loss with low back pressures. The governing equations have been solved in the frequency domain, using the decoupling approach along with appropriate boundary conditions, to derive the transfer matrix and then to calculate noise reduction and transmission loss. The predicted noise reduction values have been shown to corroborate well with experimentally observed values. Finally, parametric studies have been done to draw design curves for such mufflers.