Acoustic performance of an annular Helmholtz resonator and its application in exhaust system

Helmholtz resonator is a traditional acoustic tuning component, which consists of an enclosed volume and a throat neck. It is tuning and packaging friendly and thus has been widely used in exhaust systems. An annular Helmholtz bottle resonator usually has a straight-through pipe with a certain length of perforation. A larger sleeve is mounted to cover the straight-through pipe with one end open and the other end closed. The annular volume gap between the straight-through pipe and the sleeve becomes the neck of the Helmholtz resonator. In this research, an annular Helmholtz resonator is investigated. Numerical simulation and non-linear least square method are used to propose a correction on empirical equation to estimate the resonator targeting frequency. Afterward, this type of Helmholtz resonator is applied to a two-box exhaust system. Insertion loss is used to investigate the resonator performance in the system.