气体-颗粒两相流动力学及其在气溶胶采样中的应用

大气颗粒物切割器的工作原理主要是重力沉降、离心分离和冲击分离,是气体-颗粒物两相流的动力学分离过程.气固两相流动力学方程可以较方便地用来分析大气颗粒物在切割器中的运动轨迹,具体计算过程中阻力系数CD和边界条件应根据具体情况分析选定.本文给出了两个利用数值计算模拟切割器工作的例子,对采样仪的采样效率、切割粒径及切割器结构尺寸等设计参数对切割粒径的影响进行计算,表明两相流动力学是对采样切割器中颗粒物的运动进行数值模拟的有效工具,能对采样仪、切割器的设计、制造提供有力的帮助.

The Gas-particle Two Phase Flow Dynamics and Its Application on Aerosol Sampling

All of the monitoring and study of the ambient fine particulate employ the sampling impactor. The principles of the sampling impactor mainly include gravity deposition, centrifugal separating and impact separating. There is actually a dynamics separating process in the gas|particle two|phase flow. We can utilize the gas|particle two|phase flow dynamics equation to analyze the trajectory of ambient particle within the sampling impactor. The drag coefficient CD and boundary condition must be determined correctly according to the sampling impactor during the simulation. This paper provides two examples of simulating impactor by computation. The sampling efficiency and cut point of the sampler, the influence of design parameters such as structure and size of the impactor on the cut point have been computed. The results show the two|phase flow dynamics is an effective facility to simulate the motion of particle within impactor numerically. It can offer a powerful help to the design and manufacture of sampler and impactor.