雾环境二次气溶胶生长过程的数值研究  

NUMERICAL STUDY ON THE GROWTH PROCESS OF SECONDARY AEROSOL IN THE FOG

作　　者：丁珏[1] 王庆涛[1] 刘义[1] 应梦侃[1] 

机构地区：[1]上海大学上海市应用数学和力学研究所,上海200072

出　　处：《力学学报》2013年第2期164-170,共7页Chinese Journal of Theoretical and Applied Mechanics

基　　金：国家自然科学基金资助项目(10802046)~~

摘　　要：雾环境气溶胶之间的碰撞和凝并是气溶胶迁移、生长的动力学基础.基于颗粒群平衡方程和多重蒙特卡洛方法,针对雾环境中二次液态气溶胶生长过程开展数值研究,着重分析了湍流和布朗作用机制对单分散和指数分布的二次气溶胶碰撞凝并的影响.结果表明:雾环境气溶胶之间的碰撞凝并使得颗粒的总数目减少,颗粒平均体积逐渐增大.对于初始尺度为自由分子区、单分散的气溶胶,布朗运动时间为600 s时,二次气溶胶平均尺度增大至初始的202.7倍左右,数目降至初始的0.006.对于湍流作用下有布朗运动的二次气溶胶,在较短的时间内(如100 s)气溶胶尺度增至初始的163倍,颗粒数目降至初始的0.025倍,说明雾环境流场的湍流运动引起二次气溶胶较强的输运和聚集,导致颗粒碰撞凝并概率增加,颗粒尺度增大.The collision and coagulation between aerosols are the dynamical base for migration and growth of aerosols in the fog. Based on the particle population balance equation and multi-Monte Carlo method, a numerical study on growth process of liquid secondary aerosol was carded out. The influence of flow turbulence and brown mechanisms on secondary aerosol collision and coagulation was analyzed for the initial monodispersal and exponential distribution. The computed results show that collision and coagulation between aerosols lead to the aerosol number decreased gradually, and the average volume of aerosol increased gradually. For the initial scale of free molecular area and monodispersal aerosols, when brown movement time is up to 600 s, the average volume of aerosol is increased to about 202.7 times of the initial, but its number is decreased to 0.006 of the initial. Considering the turbulent effect and brown motion, during the short period （100 s）, secondary aerosol particle size is increased to 163 times of the initial, and its number is decreased to 0.025 times of the initial. The above phenomena illustrate that flow turbulence can cause strong transport and accumulation of aerosols, which lead to raise probability of aerosol collision and coagulation, and to increase aerosol scale gradually.

关 键 词：雾天气 二次气溶胶 生长 颗粒群平衡方程 多重蒙特卡洛方法 

分 类 号：O363[理学—流体力学]