叶片式泵内气液两相泡状流的三维数值计算

3-D calcucation of gas-oil flow in rotodynamic pump based on a bubbly flow model

为研究旋转叶片式泵中的气液两相流动规律及泵性能 ,本文根据气泡泡状流模型提出了一个两相流三维数值分析方法 .该数值计算由两部分的计算迭代完成 ,第一部分是已知含气率分布的连续相 (液相 )流场的计算 .液相流动方程的三维数值求解采用了流面坐标迭代法 .第二部分是已知液相流场后的分散相 (气泡 )轨迹的计算 .气泡运动方程中考虑了流场压力梯度差产生的力、气泡周围液体产生的阻力及由于液相质量产生的惯性力等影响气泡运动的因素 .通过对气泡运动方程进行数值求解 ,可得到泵内的含气率分布 .再将两部分的计算进行反复迭代 ,最终得到收敛解 .本文将该三维两相流数值计算方法用于多级螺旋轴流式增压泵叶轮的计算、设计 .计算结果表明 :从叶轮回转面上看 ,气泡运动转轨并不明显地偏离液相流线 .然而从叶轮子午面上看 ,几乎所有的气泡 ,不论其初始位置如何 ,它们最终都移向轮毂表面 .该三维两相流数值计算以其简单实用的特点 ,有望成为工程中气液两相增压泵的一种有效设计工具 .

A 3\|D numerical method is proposed on the basis of a bubbly flow model, in order to simulate the behavior of gas\|oil flow in a rotodynamic pump impeller.In the model,the two\|phase flow prediction technique is an iterative method composed of two parts.The first is the calcucation of continuous\|phase(liquid)velocity field assuming that the distribution of gas void fraction is given.For the 3\|D numerical solution of the liquid governing equations,a procedure called stream\|surface coordinate iteration is adopted.The second is the calculation of dispersed\|phase(bubble)trajectories when the liquid flow field is known.Governing factors for the bubble motion are the force due to the pressure gradient,the drag force due to the flow resistance of the surrounding liquid and the inertia force due to virtue mass of liquid.The equation of motion of gas bubbles are solved numerically to obtained the gas void fraction.These calculations are iterated to get a convergent solution.This method is applied to the calculation of multi\|stage helico\|axial booster\|pump impellers.It is found that the trajectories of gas bubbles do not considerably deviate from the path of liquid in blade\|to\|blade surfaces.In hub\|to\|shroud surfaces,however,almost all bubbles are finally shifted toward hub of impeller no matter where they initially were.