不同重力条件下水平管内气液两相流流型及空隙率分布的数值模拟

基于VOF方法建立了不同重力条件下水平管内气液两相流动的三维非稳态数学模型并进行了数值求解,研究了10^-4 g0,0.17 g0,0.38 g0,1 g0(90=9.8 m·s^-2)四种重力条件下水平管内气液两流型及变化规律,比较了不同重力条件下管内截面空隙率的分布和波动规律.研究结果表明,该模型能够正确预测不同重力条件下水平管内气液两相流的流型、截面空隙率和滑速比等重要参数;同一气液两相表观速度工况下,随着重力水平的升高,气相更容易在水平管的上部积聚合并,致使流型发生变化,同时,气液两相滑速比增大,截面空隙率波动峰值的平均值下降,波动频率降低;而随着气液两相表观速度的增大,两相混合工质内惯性力作用也随之增强,这将削弱重力变化的影响.

Numerical Study on Flow Patterns and Void Fraction Distribution in Gas-liquid Two-phase Flow in Horizontal Pipe Under Different Gravities

Based on the VOF（Volume of Fluid） method,a three-dimensional unsteady mathematical model is developed to study the gas-liquid two-phase flow in horizontal pipe under different gravities of 10^-4 go,0.17go,0.38 go and 1 go(go = 9.8m·s^-2).The flow patterns and their transitions are numerically investigated by the developed model and the void fraction distribution and oscillation are presented.The results indicate that the characteristics,such as flow patterns,void fraction,and slip ratio,of gas-liquid two-phase flow under different gravities can be well predicted by the developed model.Under the same two-phase superficial velocity,the gas phase accumulates and coalescences in the upper part of horizontal pipe with increasing gravity,resulting in the transition of flow patterns. In addition,with increasing gravity,the slip ratio increases while the peak and frequency of section void fraction oscillation decrease.However,due to that the increasing two-phase superficial velocity enhances the inertia force of two-phase flow,the gravity effects are weakened.