微纳颗粒两相流系统中湍流脉动效应研究综述

Review of turbulent fluctuation effect on nano-particle two-phase flow system

给出了微纳颗粒两相湍流中颗粒一般动力学方程,分析了该方程包含的因湍流脉动导致的未封闭源项;回顾了湍流脉动对颗粒成核、生长、凝并以及破碎作用的研究,包括从源项核函数的构造发展到对方程进行雷诺平均或亚格子滤波;叙述了用直接数值模拟(DNS)方法、蒙特卡洛法、大涡模拟方法(LES)以及雷诺平均方法(RANS)对方程进行求解的研究成果;介绍了对颗粒一般动力学方程进行封闭求解的研究途径,包括引入相关函数建立未封闭源项与颗粒性质、湍流场特性的关系以及直接将概率密度函数(PDF)代入未封闭源项,再通过统计学方法获得源项的平均效应;提出了将来值得进一步探讨的重要问题,包括湍流脉动对颗粒凝并的影响、实验仪器和实验技术以及对颗粒一般动力学方程中未知项的模化开展有针对性的实验研究。

The general dynamic equation(GDE)of micro/nano-particle in two-phase turbulence flow is presented,and the unclosed source terms induced by turbulent fluctuation are analyzed.The effects of turbulence fluctuation on the particle nucleation,condensation growth,coagulation and breakage are reviewed,including the modification of the source kernel function and Reynolds-average or subgrid-scale filtering to the GDE.The research results of solving the GDE using the method of direct numerical simulation(DNS),Monte Carlo,large eddy simulation(LES)and Reynolds-averaged Navier-Stokes(RANS)simulation are described.The closed approach for solving the GDE is introduced:the correlation function is used to establish the relationship between the unclosed source term and the properties of particles and turbulent flow field,the probability density function(PDF)is directly substituted into the unclosed source term,and then the averaged values of the unclosed source term are obtained by statistical method.Some important problems of further study are discussed,including the effect of turbulence fluctuation on particle coagulation,experimental instruments and techniques,and targeted experimental research on the modeling of unclosed terms in the general particle dynamic equation.