超声速旋流分离器内气液两相流流动特性

Flow characteristics of gas-liquid two phase flow in supersonic swirling separator

采用考虑颗粒碰撞的欧拉-拉格朗日数值方法对超声速旋流分离器内部复杂的气液两相流场进行数值计算。在数值模拟中,采用RNG k-ε模型模拟气相流动,采用离散相模型(DPM)追踪颗粒运动轨迹。以湿空气为介质,测量超声速分离器的轴向压力并与数值模拟结果进行对比。结果表明:数值模拟结果和测量值较为一致;气体进入超声速喷管后发生膨胀形成低温(-70℃),使天然气中的水凝结为液滴,同时气体经旋流叶片产生旋流,经中心体的收缩形成较大的离心加速度(300000 g);在巨大的离心场作用下极少部分液相颗粒随气相从扩压器流出,大部分液相颗粒与旋流分离段壁面碰撞被吸附或直接进入积液槽空间被排出,达到气液分离的目的。

Numerical simulation of particle collision process of gas-liquid flow in the supersonic swirling separator was performed with Eulerian-Lagrangian model.In the numerical calculation,the RNG k-ε model was used to simulate gas-phase flow and the discrete phase model（DPM） was used to trace moving tracks of liquid particles.The axial distributions of the static pressure in the supersonic separator were numerically and experimentally investigated using the wet air as media.The numerical results agree well with experimental data.The computational results show that gas expands in the supersonic nozzle to supersonic velocities resulting in low temperature（about-70 ℃）,which leads to the nucleation and condensation of water and hydrocarbons,followed by growth of liquid droplets.The swirling motion is generated by the vanes at the entrance of the nozzle.The swirling strength increases strongly due to the contraction of the central body.Under the great centrifugal field（300 000g,g is the acceleration of gravity）,very few liquid droplets goes into the diffuser with dry gas,and the most of liquid particles are adsorbed on the wall of swirling separation part or enter into the drainage pipe immediately.So the gas-liquid separation was achieved.