Validation of two-port temperature models for heat dissipation in exhaust systems

Abstract

The acoustic performance of exhaust systems is affected by the flow speed and temperature of the exhaust gases. The flow speed affects the convective wave speed and changes the acoustic properties of some acoustic elements such as perforates. The temperature of the exhaust gas affects its density and the speed of sound. It is important to model the flow and temperature distribution within the exhaust system in order to perform an accurate acoustic simulation. The acoustic propagation along an exhaust system can be modeled by dividing the exhaust system into a number of two-port elements. It has been previously shown that flow distribution and pressure drop calculation can be done using the same two-port elements but using a different set of transfer matrices. A similar approach was previously proposed to calculate the temperature drop using the same two-port elements but using a new set of transfer matrices. This technique has the advantage to solve all physics by defining only one network. An improved version of this formulation is presented in this paper. Several cases were tested and the thermal and acoustic results were compared to finite element simulations and measurements. The two port results matched well with the other techniques.