油气润滑管道中两相流流动的康达效应分析

Study on Coanda effect of two-phase flow in lubrication pipeline

利用FLUENT计算流体力学软件,采用康达效应的数学模型,在入口为油气环状流条件下,对气液两相流中自由空间和有限空间内液相的附壁现象进行了数值模拟,通过对比康达效应模型中不同半径的弯曲壁面及不同距离导流板的内部流场与附壁特性,得出了康达效应在油气两相流中的作用机理。结果表明,油气两相流在自由空间的液相附壁时,液相附壁的分离角在40°~60°之间,自由空间的弯曲壁面不利于液相的附壁,而有限空间正好与之相反,证明了气相良好的分配及导流对液相的分配有很好的促进作用,而且附壁面上形成的压力梯度更有利于液相的附壁。

In condition of entrance is oil-air annular flow, the phenomenon of liquid is attached to the surface about gas-liquid two-phase flow in limited and free space is simulated by FLUENT and mathematical model of the Coanda effect. Through the comparative analysis of characteristics of flow field and Coanda effect characteristics under different radius of cured surface and different distance guide plates in the Coanda effect model, the mechanism about Coanda effect in oil-air two phase flow is discussed. Results show that, when liquid phase of oil-air two-phase flow is attached to the curved surface in the free space, the separation angle of liquid is attached to a surface is in 40o^60o. This indicates curved wall is not conducive to liquid is attached to the curved surface in free space. The situation is exactly the opposite in limited space, because the good distribution and guide of gas-phase can promote the distribution of the liquid phase well. But the real reason is that the pressure gradient formed on the curved surface and liquid is attached to the curved surface easily.