热边界层内气溶胶颗粒的沉积特性研究

Aerosol particles are increasingly recognized as one of the most common unhealthy components of air pollution, it has an awful impact not only on the environment but also on the health of human beings. It is of great importance to investigate particle deposition and the evolution of particle size distribution. In the present study, the closure particle moments models will be developed based on Taylor-series expansion method, which is capable of describing the following dynamics processes, such as diffusion deposition, and thermophoresis deposition, and then the spatial distribution and temporal evolution of particles will be got. The main research topics will be concluded as follows: 1) research on the diffusion coefficient and thermophoresis coefficient in the transition regime, and the corresponding closure particle moments models; 2) the reconstruction of the particle size distribution based on the known particle moments, and the relationship between the moments and the physical parameters, such as entropy, particle specific surface energy, temperature; 3) analytical solution of TEMOM for particle deposition in the thermal boundary layer, development of the thermocouple particle densitometry. Through these studies above, the dynamic characteristic parameter of fine particles’ thermophoresis deposition will be got, which is useful for particle detection and controlled.

气溶胶颗粒是大气污染物中最主要的有害成分之一，严重影响着社会、环境及人类的健康。研究颗粒物的沉积特性，获取其尺度分布的变化规律，具有重要的理论和实际意义。本项目拟基于泰勒级数展开矩方法，构建包括扩散沉积、热泳沉积等过程在内的封闭矩模型，获取颗粒群尺寸分布在时间和空间上的演化规律：1）改善过渡区内热泳系数及扩散系数的处理方法，建立跨尺度范围的矩模型；2）基于获得的有限阶粒子矩，建立粒子尺度谱分布函数的反演模型，构建粒子矩与系统熵、表面张力、温度等物性参数之间的关系；3）获得热边界层内颗粒沉积的简化分析解，提高现有热电偶颗粒密度法的检测精度和适用范围。通过以上研究，加深对微细颗粒热泳沉积机理的认识，并为实现大气颗粒物的光学监测及控制提供理论基础。

气溶胶颗粒是大气污染物中最主要的有害成分之一，严重影响着社会、环境及人类的健康。研究颗粒物的沉积特性，获取其尺度分布的变化规律，具有重要的理论和实际意义。本项目以多分散颗粒系统的动力学演化为问题导向，以泰勒级数展开矩方法和格子玻尔兹曼方法为研究工具，开展以下研究：1）得到了连续区内热泳凝并矩模型的渐进解；2）建立了迭代直接数值模拟方法和分段二次插值反演等两种尺寸分布反演方法，由矩模型的渐进解重建粒子尺寸谱分布；3）结合热动平衡判据，分析颗粒团聚的热力学约束条件，建立了粒子矩与熵、表面能等物理参数的关系，拓宽了矩方法的应用范围；4）分析了团聚体颗粒在竖直管道中的受力情况、沉降过程及两颗粒间相互作用规律。项目共发表论文11篇，申请发明专利2项，完成了项目任务书的预期目标。