湍流场内细颗粒输运、碰撞和团聚动力学研究

Particle with aerodynamic diameter less than 2.5μm is denoted as fine particulate matter (PM2.5). Presently, PM2.5 is one of the important factors in the reducing of atmospheric visibility and the regular appearance of haze weather or any other major environmental issues. The purpose of this work is to explore the microscopic mechanism and the fundamental law of fine particles transport, collision and aggregation in turbulent field with the methods of experimental techniques, theoretical analysis and numerical simulation. Based on the experimental system of particle-surface impact, the dynamic model was built to consider the irreversible energy dissipation, energy loss caused by the liquid viscosity, sliding and rolling frictional resistance dissipation and so on. The experiment system of fine particle aggregation in turbulent field is investigated to achieve the structure of turbulent generator and the influence of particle properties and other parameters on the process of particle agglomeration and the structure of aggregate. The research on the dynamics of fine particle agglomeration in turbulent field will firstly reveal the impact of the interaction between the particles and the aggregate to the turbulent field which is previously neglected at a micro level. Secondly, it will form systematic related multi-scale characteristic of the fine particle agglomeration and develop a relatively perfect multi-scale LES-DEM model for fine particles’ agglomeration in multiphase flow system. Finally, this work will propose effective strategy for the control of fine particles and provide the theoretical foundation of fine particles’ efficient removal and control in the national economy and social development.

细颗粒物是指空气动力学直径小于2.5μm的颗粒物(PM2.5)。目前，PM2.5是导致我国大气能见度降低和阴霾天气等重大环境问题的重要因素。本项目通过实验测试、理论分析和数值模拟三大手段，深入探索湍流场细颗粒输运、碰撞、团聚的微观机理和基本规律；基于颗粒碰撞实验系统研究颗粒间相互作用机理，建立考虑不可逆能量耗散、液滴粘性导致的能量耗散、滑动和滚动摩擦阻力耗散等机制的碰撞动力学模型；搭建细颗粒湍流场内团聚实验系统，获得湍流发生器结构、颗粒物性等参数对细颗粒团聚过程及团聚体结构的影响。本项目关于湍流场细颗粒团聚动力学的研究将在微观层面上揭示以往被忽视的颗粒间相互作用和团聚体对湍流的影响，形成较系统的关于细颗粒团聚的多尺度特性的新知识；建立复杂湍流场中细颗粒团聚过程比较完善的多尺度LES-DEM模型；提出对细颗粒进行有效控制的策略和途径，为细颗粒在国民经济和社会发展中高效清除和控制提供理论基础。

细颗粒物是指空气动力学直径小于2.5μm的颗粒物(PM2.5)。目前，PM2.5是导致我国大气能见度降低和阴霾天气等重大环境问题的重要因素。本项目通过实验测试、理论分析和数值模拟三大手段，深入探索湍流场细颗粒输运、碰撞、团聚的微观机理和基本规律；基于颗粒碰撞实验系统研究颗粒间相互作用机理，建立考虑不可逆能量耗散、液滴粘性导致的能量耗散、滑动和滚动摩擦阻力耗散等机制的碰撞动力学模型；搭建细颗粒湍流场内团聚实验系统，获得湍流发生器结构、颗粒物性等参数对细颗粒团聚过程及团聚体结构的影响。本项目关于湍流场细颗粒团聚动力学的研究将在微观层面上揭示以往被忽视的颗粒间相互作用和团聚体对湍流的影响，形成较系统的关于细颗粒团聚的多尺度特性的新知识；建立复杂湍流场中细颗粒团聚过程比较完善的多尺度LES-DEM模型；提出对细颗粒进行有效控制的策略和途径，为细颗粒在国民经济和社会发展中高效清除和控制提供理论基础。