Finite wave modeling of extended-tube resonators

Abstract

Finite wave analysis of hot exhaust systems involves two modified Riemann variables and an entropy variable. These three variables move along their characteristic paths in the three characteristics approach of the method of characteristics. This paper addresses the modeling and simulation of extended-tube resonators in the time domain with the three characteristics approach. There are two known variables and seven unknown variables across an extended-tube resonator junction. Mass continuity, energy, momentum and entropy equations along with compatibility equations are simultaneously solved by means of the Newton-Raphson method to evaluate the unknown variables. The extended-tube expansion chamber is analyzed by means of the two characteristics approach as well as the three characteristics approach. The simulated results obtained by the two approaches are compared.