阶梯式涡流场涡运动特性研究

Vortex Motion Characteristics in the Reflux Area of the Shrinkable Tube

针对收缩管内收缩截面处复杂的流动情况,运用Fluent中的LES湍流模型,模拟了不同雷诺数、不同突缩比下收缩管内的流动状态,分析了不同流动状态下收缩截面下游涡流区的形成过程,通过监测下游的压力变化,探究了涡脱频率的影响因素。结果表明:在层流状态下,涡流区内仅存在一个回流涡结构,流动稳定,不存在涡脱现象;在湍流状态下,涡流区的长度不稳定,涡流区中存在多个涡结构,脱落涡在合并多个主涡后从涡流区脱出;脱落涡的强度及涡脱频率随雷诺数的增大和突缩比的减小而增大。

In view of the complex flow situation at the contraction section of the contraction tube,the LES turbulence model in Fluent was used to simulate the flow state in the contraction tube under different Reynolds number and different surge ratio,and the formation process of the downstream reflux area of the contraction section under different flow conditions was analyzed.The influencing factors of the vortex departure frequency were explored by monitoring the downstream pressure changes.The results show that in the laminar flow state,there is only one return vortex structure in the return flow area,and the flow is stable without vortex shedding.In turbulent state,the length of the return region is unstable,there are several vortex structures in the return region,and the shedding vortex exits from the return region after merging with several main vortices.The intensity and frequency of the shedding vortex increase with the increase of Reynolds number and the decrease of the outburst ratio.