Relationship between flow pulsation and entropy production rate of pump turbine
ZENG Hongji1,LI Zhenggui1*,LI Deyou2,LI Qifei3
1. Key Laboratory of Fluid and Power Machinery, Ministry of Education, Xihua University, Chengdu, Sichuan 610039, China; 2. School of Energy Science and Power Engineering, Harbin Institute of Technology, Harbin, Heilongjiang 150006, China; 3. School of Energy and Power Engineering, Lanzhou University of Technology, Lanzhou, Gansu 730050, China
Abstract：In order to study the operation stability of pump turbine under different working conditions, the flow pattern, entropy production rate distribution and pressure pulsation of model pump turbine runner and vaneless area were numerically simulated by FLUENT software, and the numerical simulation results were compared with the test. The results show that the pressure pulsation data of numerical calculation are in good agreement with the experimental values, and the drastic changes of velocity gradient and pressure gradient caused by vortex are the root cause of high energy loss in pump turbine. Compared with the design condition, the flow separation and rotating stall of the flow on the suction surface of the runner blade under small flow condition will lead to higher entropy production rate, and the amplitudes of the main frequency and the second main frequency of the pressure pulsation on the suction surface of the blade are the largest. Under the condition of large flow, the dynamic and static interference is dominant, the entropy production rate in the vaneless region is the largest, and the main frequency amplitude of pressure pulsation in the corresponding vaneless region is also the largest. It can be seen that there is a strong correlation between entropy production rate and pressure pulsation in the main flow area under various working conditions. In the area with large entropy production rate, the pressure pulsation is also large.
