自由旋片除雾器内气液两相流场数值模拟

Numerical simulation of gas-liquid two-phase flow in free revolving blade mist eliminator

为了给自由旋片除雾器结构优化设计提供理论依据,运用CAD软件建立了自由旋片除雾器的简化三维模型,运用RNGk-ε湍流模型模拟了自由旋片除雾器内部三维两相流场,得到压力场、速度场分布。结果表明,叶轮轮毂前形成局部高压区,轮毂后形成局部低压区,轮毂后有回流存在。叶轮后气流的旋转运动是由旋片的仰角引起的,而与叶轮旋转无关。当入口速度在11.5 m/s时,旋片后的最大切向速度达到20 m/s。这一现象有利于气液离心分离的实现。叶轮迎风面大部分气流的运动方向与叶轮旋转方向相反,背风面气流运动较复杂,在靠近旋片中心处存在局部涡流。对液滴相运动轨迹模拟表明,自由旋片除雾器能有效实现气液分离。

To provide theoretical basis for structural optimum design,the simplified three-dimensional plot of free revolving blade mist eliminator was developed by CAD software.RNG k-ε turbulence model was used to simulate the 3-D two-phase flow field of the free revolving blade mist eliminator.The distributions of the pressure and velocity were presented.The numerical results show that the high partial pressure zone is in front of impeller,while the low partial pressure zone is located at the back of impeller.A backflow is formed due to the low partial pressure behind of impeller.The rotary of gas-phase at the back of impeller is caused by the revolving blade elevation.This rotary motion is independent of the impeller rotation.The maximum tangential velocity can reach 20 m/s in the rear of impeller when inlet velocity is 11.5 m/s.This tangential velocity is very useful to the gas-liquid separation.The direction of the gas flow is opposite to the direction of impeller rotation at the windward side of impeller.The movement of gas flow is complex at the leeward side of impeller.There are some vortexes near the center of revolving blade.The numerical results of liquid-phase show that liquid droplet can be separated effectively from the gas by the free revolving blade mist eliminator.