基于分区RANS-LES的混流泵叶顶间隙泄漏涡流动结构及非定常特性研究  

Investigation on Vortex Structure and Unsteady Characteristics of Tip Leakage Flow in Mixed-flow Pump by Zonal RANS-LES

作　　者：刘亚斌 谭磊[1,2] 韩亚东 LIU Yabin;TAN Lei;HAN Yadong(State Key Laboratory of Hydroscience and Engineering,Tsinghua University,Beijing 100084;Department of Energy and Power Engineering,Tsinghua University,Beijing 100084)

机构地区：[1]清华大学水沙科学与水利水电工程国家重点实验室,北京100084 [2]清华大学能源与动力工程系,北京100084

出　　处：《机械工程学报》2024年第24期309-316,329,共9页Journal of Mechanical Engineering

基　　金：国家重点研发计划(2020YFB1901401);佛山-清华产学研合作协同创新专项(2020THFS0107);水圈科学与水利工程全国重点实验室开放基金(sklhse-2023-E-03);国家自然科学基金(51809148);北京市自然科学基金(3192015)资助项目。

摘　　要：基于分区边界处雷诺平均(Reynolds-averaged Navier-Stokes,RANS)和大涡模拟(Large eddy simulation,LES)的湍流应力项混合,实现RANS到LES的快速过渡;同时,在LES计算区域内近壁区引入无量纲壁面距离限制器实现边界层内部流动的模化处理,发展了适应叶顶间隙泄漏涡流特征的RANS-LES分区混合计算模型。基于该混合计算模型,在混流泵设计工况下进行精细的非定常数值计算,研究叶顶间隙泄漏涡流动结构及非定常特性。根据生成机理和分布区域的特点,混流泵叶顶间隙泄漏涡可分为主泄漏涡、次泄漏涡和分离涡三种结构。在叶顶间隙内存在显著的流动分离,在叶顶吸力侧附近存在强烈的流动相干剪切。随着叶片压力面和吸力面压差的增加,平均泄漏流速逐渐增大。叶顶间隙涡流区湍动能生成与间隙射流-主流的剪切效应、主泄漏涡-主流的相干作用密切相关。间隙射流-主流剪切区和主泄漏涡区的压力脉动最为剧烈,主泄漏涡涡心轨迹点的压力脉动强度逐渐下降。A Zonal RANS-LES model is developed according to the tip leakage vortex(TLV)features,based on the fast transition from Reynolds-averaged Navier-Stokes(RANS)to large eddy simulation(LES)achieved by blending the turbulence stresses around the RANS-LES boundary.Moreover,the wall modelling treatment is applied by forcing the near-wall boundary layer in the LES scope to be running in RANS mode.Based on the developed Zonal RANS-LES method,a high-fidelity unsteady simulation of a mixed flow pump under design condition is performed,and the vortex evolution and unsteady characteristics of the flow field in the impeller are further investigated.According to the generation mechanism and distribution features,the TLV is categorized into three types:primary tip leakage vortex(PTLV),secondary tip leakage vortex(STLV)and tip separation vortex(TSV).There is a significant flow separation inside the tip clearance,and a strong shear interaction is observed near the blade suction side.As the pressure difference between the blade pressure surface and suction surface increases,the average tip leakage flow rate gradually increases.The generation of turbulent kinetic energy in the TLV region is closely related to the tip leakage jet-mainstream shear effect and the PTLV-mainstream interaction.The most intense pressure fluctuation is presented in the tip leakage jet-mainstream shear region and the PTLV-mainstream interaction region,and the pressure fluctuation intensity decreases along the PTLV trajectory.

关 键 词：混流泵 叶顶间隙 泄漏涡流 分区RANS-LES 非定常特性 压力脉动 

分 类 号：TG156[金属学及工艺—热处理]