A study of shape optimization method on connection cones for diesel particulate filter (DPF)

For diesel vehicles equipped with a Diesel Particulate Filter (DPF), flow resistance (pressure drop) is a vital factor affecting power performance, fuel consumption and regeneration performance. Traditional methods for DPF pressure drop reduction mainly focus on developing a new filter material, optimizing its microstructure and structural parameters of gas channels. Although the above methods have greatly reduced the pressure drop, it is still difficult to meet the demand of increasingly stringent energy consumption and carbon emissions standards. Thus, improving the shape of connection (inlet and outlet) cones to further reduce pressure drop has become one of the important topics of DPF development. In this paper, a simulation model of gas-particle two-phase flow through traditional connection cones has been established and wall-flow filter element is modeled with an equivalent porous material. The flow through DPF has been simulated with Fluent computational fluid dynamics (CFD) software under different exhaust emission velocities, expansion angles and ratios. The influence factors for flow uniformity and pressure drop in DPF have been analyzed. The variation tendency of pressure drop, flow velocity, vorticity, and turbulent kinetic energy in connection cones has been obtained. And then, based on calculation results and Non-Uniform Rational B-Splines (NURBS) theory, the fitting cure of optimum connection cones are drawn out at different expansion angles and ratios, compared with the calculation results of traditional connection cones, to deduce advantages of optimum connection cones on the flow uniformity and pressure drop.