基于动态混合模型的离心泵导叶端面间隙流动特性研究

As a new type of structure, the half vane diffuser can effectively improve the hydraulic performance of centrifugal pump. It is the foundation of improving the hydraulic design method to master the flow mechanism of the end clearance. In this project, the centrifugal pump with the half vane diffuser is taken as the research object, and the flow mechanism on end clearance of half vane diffuser is studied both numerically and experimentally. To take the effect of streamline curvature and rotation on the flow field into consideration and then conduct accurate analysis on the flow pattern in the near wall region and the flow field in the turbulent core region, a dynamic mixed RANS-LES turbulence model was establish. In addition, a numerical calculation method was established to accurately capture flow field information of the centrifugal pump with half vane diffuser. Combined with visual experimental method, the unsteady fluctuation characteristics of the end clearance flow of the half vane diffuser under different flow conditions and different rotating speeds were revealed. The formation mechanism and motion trajectory of leakage flow as well as eddy current in the end clearance of guide vane are studied. The influence of the gap structure and characteristic parameters on the unsteady flow field for the performance and inner field in centrifugal pump was investigated. The association rules between the performance of centrifugal pump and the end clearance of half vane diffuser was established, which provided theoretical basis for improving the hydraulic performance and stable operation of the centrifugal pump with vane diffuser.

半高导叶作为一种新型结构，能够有效地改善离心泵水力性能，掌握其端面间隙流动机理是完善其水力设计方法的基础。本项目拟以半高导叶离心泵为研究对象，采用数值模拟与实验相结合的方法对半高导叶端面间隙流动机理进行研究。考虑流线曲率与旋转对离心泵流场影响，构建精细分析近壁区流动形态与湍流核心区流场的动态混合RANS-LES湍流模型，建立精确捕捉半高导叶离心泵全流场信息的数值计算方法。结合可视化实验方法，揭示不同流量工况、不同转速时半高导叶端面间隙流的非定常波动特性；探究导叶端面间隙泄漏流与涡流的形成机理及运动轨迹。探索半高导叶端面间隙结构与特征参数对离心泵外特性与内部流场等性能的影响规律，进而建立半高导叶端面间隙与离心泵性能的关联规律，为提高导叶式离心泵水力性能与稳定运行提供理论依据。

导叶是离心泵中重要过流部件，广泛应用于多级或特殊要求的单级离心泵中。半高导叶作为一种新型结构，能够有效地改善离心泵水力性能，掌握其端面间隙流动机理是完善其水力设计方法的基础。本项目考虑流线曲率与旋转对其流场影响，构建精细分析近壁区流动形态与湍流核心区流场的动态混合RANS-LES湍流模型；再此基础上，采用数值模拟与实验方法重点分析不同流量工况、不同转速时半高导叶端面间隙流的非定常波动特性；探索导叶端面间隙泄露流与涡流特征的运行轨迹及演变规律；探究半高导叶端面间隙结构与特征参数对其间隙非稳态流场的影响机制。本项目建立了精确捕捉半高导叶离心泵全流场信息的数值计算方法；揭示了半高导叶端面间隙非稳态流动机理，同时阐明了动静干涉作用与导叶端面间隙流的响应关系；建立了导叶端面间隙泄露流理论模型；提出了改善导叶式离心泵水力性能与稳定运行的理论方法。依托本项目，发表相关学术论文6篇、其中SCI/EI论文5篇，协助培养研究生2名，参加与本项目相关的国内外学术会议3次。本项目的研究成果可为详细捕捉离心泵非稳态流场的数值模拟方法改进奠定良好基础，为离心泵非稳态间隙流与涡流特征的理论研究提供参考，为离心泵过流部件的优化设计方法及泵性能的改进提供理论依据与参考。