涡轮转子叶尖区流动损失机理研究

An in-house detached eddy simulation program was employed to simulate the flow in the turbine rotor blade tip region， obtaining high-precision flow field data， in order to comprehensively investigate the physical process of local aerodynamic loss in this region. Afterwards，the local mixing loss caused by mixing between tip leakage and mainstream flows in the tip clearance region was quantitatively assessed using entropy production analysis. Additionally，the mechanisms and contributions of the time-averaged flow field and fluctuating flow field to the entropy production rate were explored. The results demonstrated that both time-averaged and fluctuating entropy production are important sources of the mixing loss. Time-averaged entropy production dominates upstream losses，whereas fluctuating entropy production dominates downstream losses. The generation and spatial distribution of the time-averaged entropy production are determined by the normal velocity profile of the tip leakage jet. Time-averaged entropy production varies in magnitude and spatial distribution due to the differences in shear strength and the thickness of the tip leakage flow boundary layers in the upstream and downstream location. The generation of the fluctuating entropy production is dominated by the amplification term caused by the time-averaged strain rate tensor and the pressure Hessian term caused by the vortical structures in the fluctuating flow field.