General Collocation Method for Three Dimensional Acoustic Analysis of a Simple Expansion Chamber.

Abstract

Acoustic analysis of a simple expansion chamber using a three dimensional finite element model is time consuming because of enormous computation. Numerical collocation method utilizing boundary conditions of acoustic pressure and particle velocity, has been developed for an efficient alternative. However, this conventional method cannot be generally applied to a simple expansion chamber with arbitrary inlet/outlet. This paper introduces a general collocation method without any limitation on inlet/outlet, to calculate four-pole parameters of the simple expansion chamber. Acoustic characteristics of simple expansion chamber with rectangular and circular cross section is analyzed using the suggested method and compared with that of conventional collocation method. Results of finite element method reveals that the suggested method has better accuracy compared with the conventional method