测量口壁面粗糙度对PM2.5流动特性的影响

摘要

This paper is aimed at addressing the measurement precision resulting from the change in measurement port roughness triggered by the long-term use of optical dust meter. The study drawing on the hydrodynamics of gas-solid two-phase flow theory analyses the flow characteristic of PM2. 5 with the dif-ferent roughness in measurement port using the turbulence model and discrete phase model of Lagrange. The results show that, compared with the velocity of PM2. 5 near the smooth wall, there is a decrease in the velocity of PM2. 5 particles near the measuring port if the absolute equivalent roughness is greater or smaller than 2. 5μm, and some of PM2. 5 particles are more likely to deposit or strand in the wall of meas-urement port, affecting the measuring accuracy. The study could provide a necessary basis for the design of the gas path of related monitor device.%针对光学粉尘测量仪长期使用时测量口粗糙度改变影响测量精度的问题,以流体力学的气固两相流理论为基础,采用湍流模型和拉格朗日离散相模型分析不同粗糙度下测量口PM2.5的流动特性.结果表明:与光滑壁面PM2.5的速度相比,绝对当量粗糙度大于或小于2.5μm时,测量口附近PM2.5的粒速均下降,且部分PM2.5粒子容易沉积或滞留在测量口壁面,影响测量精度.该研究可为相关监测仪器的气路设计提供必要的依据.