制动工况桃腔偶合器三维涡特征分析及仿真评价

Three-dimensional vortex characteristic analysis and simulation evaluation of peach cavity hydrodynamic coupling under braking condition

基于大涡模拟采用不同亚格子湍流模型仿真桃腔液力偶合器制动工况下流场,采用Q准则涡识别方法提取涡轮三维多尺度涡结构特征。通过粒子图像测速流场可视化试验验证及评价仿真结果的准确性和可靠性。从三维涡与二维流场提取两方面综合来看:WMLES S-Ω模型对叶片近壁面三维多尺度涡仿真信息丰富,小尺度涡捕获准确;WALE模型对叶片与外环交汇角隅区小尺度涡识别准确;WMLES S-Ω模型对主流区二维流场仿真结果真实,能呈现角隅区二次流现象;WMLES模型对叶片近壁面二维流场仿真数值分布与试验值吻合。研究结果可为液力偶合器流场仿真提供一定的理论与技术指导。

Based on large eddy simulation,different sub-lattice turbulence models are used to simulate the flow field of a peach cavity hydrodynamic coupling under braking condition.The Q-criterion vortex recognition method is used to extract the three-dimensional multi-scale vortex structure inside the turbine.The unsteady multi-scale vortex spatiotemporal evolution law,energy transfer and loss mechanism inside the turbine is analysed based on the vortex dynamics theory.In order to verify and evaluate the accuracy and reliability of the simulation results,the velocity field and vorticity field are extracted based on flow field visualization experiment by particle image velocimetry.From the perspective of the qualitative identification of three-dimensional vortex structure spatiotemporal characteristics and the quantitative extraction of twodimensional flow field parameters:WMLE S-Ωmodel simulation can provide rich information of threedimensional multi-scale vortex of the near-wall region on the blade,the small-scale vortex can be captured accurately.WALE model simulation can accurately identify small-scale vortices in the corner area where the blade and the outer ring intersect.The simulation results of the two-dimensional flow field in the mainstream area by WMLES S-Ωmodel tend to be true,the secondary flow phenomenon in the corner area can be presented accurately.The numerical distribution of the two-dimensional flow field simulation in the near-wall region on the blade by WMLES model is consistent with experimental values.The research results can provide certain theoretical and technical guidance for the flow field simulation of hydrodynamic coupling.