【摘要】 为了优化柴油机颗粒捕集器的捕集、压降性能,本文基于孔径概率密度函数和孔隙率分布函数建立了二维柴油机颗粒捕集器孔道微观结构模型,考虑了拦截机理和扩散机理用以计算颗粒在过滤器中的沉积分布情况和捕集效率。计算结果表明:多孔介质微观结构和入口速度对颗粒捕集效率的影响与粒径有关,100 nm粒径颗粒随流速增大初始捕集效率降低最为明显,1 000 nm粒径颗粒在不同均匀性的过滤壁下的捕集效率差超过了30%;孔径分布函数方差越大,颗粒就会更多地分布在过滤壁前端,捕集效率也越高,但较大的孔径方差会导致捕集器的初始压降增大和捕集过程结束时的性能出现恶化。更多还原

【Abstract】 To optimize the pore structure of a diesel particulate filter and improve its capture and pressure drop performance, a two-dimensional DPF pore microstructure model was established based on the pore size probability density function and porosity distribution function. We considered the interception and diffusion mechanisms to calculate the deposition distribution and filtration efficiency of particles in the filter. Results revealed that the influence of porous media microstructure and inlet velocity on the filtration efficiency of soot particles was related to the particle size. The initial capture efficiency of 100 nm particles decreased with an increase in inlet velocity. The difference in filtration efficiency of 1 000 nm particles under different heterogeneous filter walls exceeded 30%. The larger the variance of pore size distribution, the greater the number of particles distributed in front of the filter wall,and the higher the filtration efficiency can be realized. However, excessive variance of pore size distribution would lead to an increase in initial pressure drop and serious deterioration of the pressure drop performance of the filter at the end of the filtering process.更多还原