多组分烃类混合物气液两相流格子玻尔兹曼模型

A Lattice Boltzmann model for multi-component vapor-liquid two phase flow

针对传统格子玻尔兹曼模型无法处理真实多组分混合物气液两相流的问题,提出了一种新的基于四参数(临界温度、临界压力、偏心因子、体积修正因子)状态方程的多组分格子玻尔兹曼模型。模型首先使用烃类混合物状态方程计算混合流体间作用力,并提出一种将混合流体作用力分配给各流体组分的方法,从而计算出混合流体中各组分所受作用力,再使用精确差分方法将组分作用力引入格子玻尔兹曼模型。同时为正确反应黏度变化对多相体系流动过程的影响,引入LBC(Lorentz-Bray-Clark)黏度模型计算混合流体的黏度。利用该模型,分别模拟了甲烷、乙烷、丙烷等多组分气液两相共存问题。新模型计算结果与使用逸度平衡方法获得的理论解吻合度较高,验证了新模型的正确性。

In traditional multi-phase multi-component Lattice Boltzmann （LB） models, the phase properties especially the vapor-liquid equilibrium calculations failed to model the actual flow realistically. A new multi-component vapor-liquid two phase LB model that involves a four-parameter （critical temperature, critical pressure, acentric factor and volume shift factor） equation of state （EOS） is proposed. The new model employs a four-parameter EOS to calculate the force on each lattice and then to determine the force between different fluid phases accurately. An accurate difference method is proposed to integrate the interaction force into the evolution fimctions of each component. Moreover, the Lorentz-Bray-Clark viscosity model is implemented to calculate the viscosity of lattice fluid according to the component density. The new model is validated and applied to forecast the phase behavior of methane, ethane, and propane mixture at multiple temperatures and pressures. The simulation results show a good agreement with experimental data and theoretical predictions.