3-D Numerical Study of Fluid Flow and Pressure Loss Characteristics through a DPF with Asymmetrical Channel size

The main objective of the current paper was to investigate the fluid flow and pressure loss characteristics of DPF substrates with asymmetric channels utilizing 3-D Computational Fluid Dynamics (CFD) methods. The ratio of inlet to outlet channel width is 1.2. First, CFD results of velocity and static pressure distributions inside the inlet and outlet channels are discussed for the baseline case with both forward and reversed exhaust flow. Results were also compared with the regular DPF of same cell structure and wall material properties. It was found that asymmetrical channel design has higher pressure loss. The lowest pressure loss was found for the asymmetrical channel design with smaller inlet channels. Then, the effects of DPF length and filter wall permeability on pressure loss, flow and pressure distributions were investigated. For a same size DPF with the same geometrical parameters, the optimal DPF length (with the least pressure loss) was longer for the DPF with asymmetrical channels. The 3-D CFD model was further calibrated for the prediction of pressure loss with soot loading based on test data for a soot loaded DPF. CFD predictions showed that the pressure loss for the DPF with asymmetrical channels was higher than that of the regular DPF at low soot loading. As the soot loading increases and reaches a certain value, 5.5 g/L in current study, same pressure loss was found between the regular DPF and the DPF with asymmetrical channel. The opportunity of using asymmetrical channel DPF as the partial filter was discussed. The initial soot loading of this partial DPF can be as high as 50% to 60% depends on wall permeability.