基于大涡模拟的动静叶栅内固液两相流动

Solid-liquid two-phase flow in rotor and stator cascades based on LES

为研究离心泵动静叶栅内固液两相非定常流动情况,了解流道内的流动细节,以导叶式离心泵为研究对象,采用ICEM软件对模型泵进行结构化六面体网格划分,基于Mixture混合模型和滑移网格(sliding mesh)技术,运用大涡模拟(large eddy simulation,LES)模型对其全流道进行三维非定常数值计算.对比分析了清水和固液两相2种介质时,动静叶栅内的拟序涡流结构及演化过程的不同,并分析了固液两相流介质时流道内几个不同位置处涡的演化.结果表明:泵在输送清水和固液两相介质时,附着涡的结构基本保持不变,而由于叶轮旋转所产生的涡,在叶轮旋转运动的过程中则会有卷曲、合并、撕裂的演化形式;流道内的涡量大小分布规律在清水和固液两相介质下是相同的,但是固体颗粒的加入会加快涡的耗散速度,并且涡产生的位置和合并形式都发生了变化;固液两相介质时,动静叶栅内的涡在不同位置的演化过程是不同的.

In order to study unsteady solid-liquid two-phase flows in rotor and stator cascades of centrifugal pump and understand the flow details in the flow passages,a centrifugal pump with radial diffuser is chosen,and then the unsteady 3D flow field is simulated based on the mixture multiphase model and sliding mesh as well as the large eddy simulation( LES) turbulence model with structures mesh generated in ICEM. The evolution process of coherent vortexes in the two cascades is exploited and the change in vortex pattern at different locations is analyzed in the solid-liquid two-phase flow by comparing with single phase water flow. The results show that the pattern of attached vortexes remains unchanged basically under two-phase and single phase flow conditions. The vortexes produced by impeller rotation experience a series of evolution process,namely curling,merging and breaking. Even though the solid particles affect the distribution of vorticity in the flow field in the pump a little,they accelerate the dissipation of eddy energy and alter the vortex location and breaking pattern. The evolution process of vortexes depends on positions considered in the cascades under either single or twophase flow condition.