Modeling DPF units beyond the plane wave range

Abstract

Diesel engines produce harmful exhaust emissions and high exhaust noise levels. One way of mitigating the exhaust emissions is the use of Diesel Particulate Filters (DPF). They are known to possess good acoustic attenuation properties. It is therefore of interest to characterize and simulate the acoustic performance of these filters. There have been several successful attempts to model the sound propagation across Diesel Particulate Filters. These attempts are based on the assumption of plane wave propagation along the axis of the filter. It has been shown that the sound propagation along the cross modes can be negligible even above the plane wave limit of the filter diameter. These filters are usually connected to complicated cavities with side inlets and outlets which need modeling of higher order modes above the plane wave limit. The Finite Element Approach is a common method to analyze the acoustics of exhaust system components beyond the plane wave region. It is computationally expensive to include the sound propagation inside the narrow tubes in the analysis. This paper proposes an equivalent fluid model for the filter to use within the Finite Element Calculations. The suggested approach is validated experimentally.