小尺度不可压粘性气液两相流中分界面拓扑改变的水平集方法数值模拟(英文)

用一类不含有重新初始化步骤的水平集方法模拟一小团气体由于浮力上升到气液水平分界面并破裂以及其后的一系列有旋运动过程。气液分界面从两个单连通面开始发生拓扑改变。数值例子中捕获了此运动过程的诸多特征，如胞腔，向上的射流，沿界面的粘性、重力、毛细波，以及从射流断裂开来的更细小的液滴和浪花翻卷。雷诺数可以很小，也可以很大。表面张力，重力加速度也可以在很大范围内变化，这是地面实验难以实现的。

机械密封液-气分界面的参数及特性分析

符号Am、Bm:富氏系数; C:密封间隙; e:波幅; h:液膜厚度; n:波数; P:压力; P?:密封压力; q:单位长度容积流量; Qrms:均方根流量; r:径向坐标; T:扭矩; W:载荷; α:泵送角度; γ:润湿角度; θ:角度坐标; μ:液体粘度; σ:表面张力; 一、前言环槽形结构组成的机械密封系统中,由于环槽的泵送效应。

惯性力驱动微尺度下液柱运动模型

为快速预测微尺度下液柱受惯性力作用时其分界面的运动位移,基于非定常伯努利方程建立了其理论模型.首先,推导了惯性力作用下微液柱的运动方程.然后,利用封闭的环形微通道仿真模型,对微液柱受阶跃型加速度作用时的动态响应进行了数值仿真,利用仿真数据拟合得到了对应的待定系数k值,并进一步确定了k值表达式.最后,制作了微通道实验样机,利用高速摄影机和离心实验平台进行离心加载实验.结果表明,所建立的惯性力驱动微液柱运动模型,可用于预测微尺度下液柱的分界面运动位移,其计算精度满足工程设计要求.

搅拌罐内基于EDEM-FLUENT耦合的多相流混合数值模拟

利用EDEM-FLUENT联合仿真,采用VOF(Volume of Fluid)法和欧拉-拉格朗日模型,组成离散固体与连续的液相和气相的混合模型,对搅拌罐内固-液-气三相流动进行数值模拟,探究固体颗粒在搅拌罐内的运动状态和自由液面对其分散的影响.基于FLUENT软件的VOF法对气-液连续相建模,很好地捕捉气液分界面,模型更接近实际工况,直观显示自由液面的变化;基于离散元法使用软件EDEM对固体颗粒进行离散单元建模,通过两软件的联合仿真直观模拟固体颗粒在罐内的位置信息和运动情况,得到的固体颗粒分散情况与利用欧拉法得到的结果一致.

Stability of Stratified Gas-Liquid Flow in Horizontal and Near Horizontal Pipes

A viscous Kelvin-Helmholtz criterion of the interfacial wave instability is proposed in this paper based on the linear stability analysis of a transient one-dimensional two-fluid model. In thismodel, the pressure is evaluated using the local momentum balance rather than the hydrostatic approximation. The criterion predicts well the stability limit of stratified flow in horizontal and nearly horizontal pipes. The experimental and theoretical investigation on the effect of pipe inclination on the interfacial instability are carded out. It is found that the critical liquid height at the onset of interfacial wave instability is insensitive to the pipe inclination. However, the pipe inclination significantly affects critical superficial liquid velocity and wave velocity especially lor low gas velocities.

The Mechanism of Interfacial Mass Transfer in Gas Absorption Process

Based on the method of molecular thermodynamics, the mass transfer mechanism at gas-liquid interface is studied theoretically, and a new mathematical model is proposed. Using laser holographic interference technique, the hydrodynamics and mass transfer characteristics of CO2 absorption are measured. It is shown that the calculated results are in good agreement with the experimental data.

Gas–Liquid Mass Transfer Characteristics in a Gas–Liquid–Solid Bubble Column under Elevated Pressure and Temperature

abstract The volumetric mass transfer coefficient kLa of gases （H2, CO, CO2） and mass transfer coefficient kL on liquid par-affin side were studied using the dynamic absorption method in slurry bubble column reactors under elevated temperature and elevated pressure. Meanwhile, gas-holdup and gas-liquid interfacial area a were obtained. The effects of temperature, pressure, superficial gas velocity and solid concentration on the mass transfer coeffi-cient were discussed. Experimental results show that the gas-liquid volumetric mass transfer coefficient kLa and interfacial area a increased with the increase of pressure, temperature, and superficial gas velocity, and decreased with the slurry concentration. The mass transfer coefficient kL increased with increasing superficial gas velocity and temperature and decreased with higher slurry concentration, while it changed slightly with pressure. Ac-cording to analysis of experimental data, an empirical correlation is obtained to calculate the values of kLa for H2 （CO, CO2） in the gas-paraffin-quartz system in a bubble column under elevated temperature and elevated pressure.