由湍动导致纳米颗粒数密度增减和扩散的两相湍流研究

纳米颗粒两相流存在于大量的自然现象和实际应用中且具有特殊性和复杂性，因此，对其研究具有重要的实际意义和科学价值。然而，在以往的研究中，通常将由湍流脉动导致的纳米颗粒数密度的增减和扩散项忽略，从而不能真实地反映纳米颗粒两相流中颗粒数密度的演变乃至整个流场的特性。本项目(1)拟进行理论研究，建立由湍流脉动导致的纳米颗粒数密度增减和扩散项的表达式，在此基础上，建立纳米颗粒两相湍流场中完整的颗粒数密度雷诺平均平衡方程。(2)拟将该方程转换为矩方程后，采用泰勒级数展开矩方法在槽道流场中进行数值求解，给出两相流经过槽道后的颗粒数量、质量、粒径、粒径标准方差等分布的结果。(3)拟进行相应的实验研究，通过与计算结果比较，证实所建模型与数值模拟方法的可行性。通过以上研究，为描述具有不同特征尺度作用的纳米颗粒两相湍流场提供新的途径，加深对纳米颗粒两相湍流场流动特性的认识。

Nanoparticulate two-phase flow occurs in a wide range of natural phenomena and practical applications, and has its particularity and complexity. Therefore, it is of practical significance and theoretical importance to study such flow. However, the terms of increase, decrease and diffusion of nanoparticle number density induced by turbulent fluctuation are usually neglected in the previous investigations, so that the evolution of the nanoparticle number density and flow property in the nanoparticulate two-phase turbulent flows cannot be described truly. In this project, (1) The expression of increase, decrease and diffusion of nanoparticle number density induced by turbulent fluctuation is proposed through theoretical research. Based on the expression, the completed Reynolds averaged balance equation of particle number density is built. (2) The balance equation is transformed to the moment equation which is solved numerically with the Taylor-series expansion method of moment in the channel flow. The distribution of particle number, mass, diameter and its standard variance are obtained. (3) Corresponding experiment is performed, and the feasibility of proposed model and numerical method are validated by comparing the numerical and experimental results. Through above research, a new approach describing the Nanoparticulate two-phase turbulent flows with function of different scale is offered, and the understanding of the flow characteristics of the nanoparticulate two-phase turbulent flows is deepened.