FEM Analysis on Acoustic Performance of Wall Flow Diesel Particulate Filters

Diesel powered vehicles, in compliance with the more strict exhaust emission standards such as Euro V, is likely to require a diesel particulate filter (DPF). A DPF used on a vehicle will affect the acoustic emission of the diesel engine, so it is important to investigate the sound propagation rule in DPF and further to propose the optimum DPF design. However, due to the geometrical complexity of the DPF, the traditional analysis method, such as analytical method, can not assess the acoustic performance of DPF accurately in medium and high frequency band. In this paper, a combined approach of finite element analysis and viscosity correction is proposed to predict acoustic performance of DPF. A simplified model of the full DPF is established and is used to analyze the sound propagation characteristic of the DPF. The distribution of the sound pressure and velocity, the transmission matrix of the DPF are obtained using the finite element method. In addition, the method of the viscosity correction is used in the transmission matrix of the DPF to evaluate the acoustic performance of DPF. Based on the FEM computation and the viscosity correction, the transmission losses under the rated load and idle condition of a diesel engine are calculated. The calculation results show that DPF can effectively attenuate exhaust noise, and sound attenuation increase with the rise of the frequency. Sound attenuation is better under rated condition than idle condition of diesel engine, particularly in frequency above 1 000 Hz.