混流泵叶顶间隙涡流的流动特征及动力学模态研究

The tip clearance in mixed-flow pump is tiny in dimension. However, the flow pattern in tip clearance region is quite complicated, which will generate remarkable impact on the efficiency and operation stability of pump. The present research focuses on the flow characteristics and evolution process of primary TLV (tip leakage vortex), secondary TLV, entangled TLV and dispersed TLV. The in-depth mechanism for the formation, diffusion and dissipation of every TLV types will also be analyzed. The key characteristic parameters of TLV pattern, including inception location, separation angle and vortex intensity of TLV will be researched. The flow rate, tip clearance size, and cavitation number are taken into consideration to evaluate their influence on the three characteristic parameters. With the dynamic mode method, the present research will conduct innovative works on the decomposition, superposition and reconstruction of flow field in tip clearance region. The flow structure corresponding to specific mode will be researched. Plenty of efforts will be paid to reveal the interaction of flow structures at different modes and its influence law on the flow field.

混流泵叶顶间隙区尺寸狭小，流动形态复杂，对泵的高效稳定运行影响重大。本项目研究泄漏涡流的主泄漏涡、次泄漏涡、纠缠涡和离散涡的流动特征和演化机理，深入揭示各涡型的生成、扩散和耗散的内在机理。给出不同流量，叶顶间隙尺寸和空化数下，泄漏涡流特征参数：涡初生位置，涡分离角和涡强度的关联规律。通过动力学模态方法，从新的角度实现间隙涡流流场的分解、叠加和重构，确定不同模态对应的流动结构，揭示不同模态流动结构的相互作用及其对流场的影响规律。

混流泵叶顶间隙区尺寸狭小，流动形态复杂，对泵的高效稳定运行影响重大。本项目在涡流特征方面，考虑叶顶间隙尺寸、叶轮转速、叶片栅距等几何参数和运行参数，对混流泵旋转叶轮的能量性能、流动特征和压力脉动特性进行了系统的参数化研究，阐明了间隙泄漏流动诱发的各涡型的结构特性和时空演化过程，揭示了叶轮各几何参数和运行参数与泄漏涡流特征的关联规律，为考虑间隙涡流的叶轮水力设计及优化奠定了基础。深入研究了间隙涡流结构和湍流能量的空间分布特性和时频演变规律，并引入动力学模态分析方法实现间隙涡流时空演化过程的分解、叠加和重构，阐明了不同模态流动结构的耦合机制，揭示了间隙涡流湍流能量的主导频率和物理机理，建立了间隙涡流的动力学模态特征、能量频谱与间隙涡流空间结构、时变特征的映射规律。本项目系统深入研究了混流泵叶顶间隙涡流的流动特征及动力学机理，为其性能优化和稳定运行奠定了重要方法和理论基础。