小开度节流阀流场特征及空化流动的数值分析

基于两相空化流动的控制方程和湍流模型,对节流阀在小开度下的流场特征及空化流动进行数值分析。结果表明:流体在流经节流口时,流速急剧增加,压力迅速降低至液体的饱和蒸汽压以下,形成空化。当节流阀出入口压差增大时,出口边界流速明显提高,出口两侧的流速差异更加明显,且在低速流一侧形成涡流。并且,出入口压力差的增加、阀门开度的减小会导致空化区域扩大,强度增加。研究成果可为节流阀的后续优化设计和操作提供理论依据。

Numerical Simulation on Flow Field Characteristics and Cavitating Flow at Small Opening of Throttle

Based on the equation of two-phase cavitating flow and turbulence model,the numerical analysis on flow field characteristics and cavitating flow phenomenon at small opening of throttle was finished.The results showed that： the flow velocity increased dramatically when the fluid flow through the gap between the valve spool and seat.Simultaneously,the local pressure decreased rapidly lowered to the saturation vapor pressure,resulting in the formation of cavitation.When the pressure difference between the import and export of throttle valve is increased,the velocity in the outlet boundary will increase significantly,and the outlet velocity difference on the both side of pipeline becomes more pronounced.Besides,a vortex will form on the side of low flow velocity.Besides,the increasing of pressure difference between the import and export of valve or the reducing of valve opening will result in the growth of cavitaion region and intensity.The research results above can provide a theoretical basis of optimum design and operation for the throttle.