Research And Simulation On Particulat Trapping Performance In The Diesel

Comparing with the petrol engine, the diesel engine has the advantages of high thermal efficiency and good fuel economy, but has more pollutants. In order to meeting higher rules of exhausts, the post treatment like particulate filter has become one of the most effective measures to reduce emission in the diesel, except for engine inside purifying method such as combustion- optimizing. The factors that affect the trapping performance are the engine behaviours, the structures and properties of the particulate filters and so on. It will provide a powerful foundation to design a high-performance particulate filter by using simulation methods to simulate the various factors systematically which affect the trapping efficiency before the experimental study. The main research works are focused on the following aspects:(1) Studied the characteristics of foam ceramics and particulate filtration mechanism systematically, designed the ceramic performance testing bench, and tested the flow parameters of the fluid dynamics performance in the foam ceramics of 10PPI and 25PPI.(2) Designed two-dimensional periodic porous media model by the Computational Fluid Dynamics (CFD) software–FLUENT; verified the rationality of the model by comparing the experimental model under the same boundary conditions.(3) Established particle trajectory model; Simulated, tracked and analysised the particle’s motion trail in the porous model by using Discrete Phase Model (DPM). A further study of the trapping efficiency is carraied out by analyzing the four factors such as flow velocity, particle diameter, the specification and the thickness of foam ceramics. The result shows that the trapping efficiency of the 25PPI is higher than 10PPI, as well as the greater pressure drop, under the same conditions of paticle size and flow velocity.(4) Optimized the structure of the ceramics assembly to improve the trapping efficiency. Simulation shows that the ceramics assembly with an interval between foam ceramics can improve the trapping efficiency, the larger interval the highter efficiency.In a word, this paper provided a great deal of references for optimizing the particulate filter, reduced the time-consuming of the structure design and provided a guide for the following engine bench testing research.