巨型混流式水轮机宽负荷工况空化现象研究OA

A numerical simulation study is carried out to investigate the unsteady cavitating flow characteristics of a Francis turbine under a gross head of 135 m at typical load conditions ranging from 650 MW to 850 MW,and the simulation results are compared and validated against model test data.The calculated results indicate that noticeable cavitation only occurs near the draft cone outlet under the 850 MW load condition,with its location and morphology being generally consistent with the experimental observations.At the load conditions of 750 MW and above,multiple high-frequency peaks appear in the frequency range of 95-101 Hz,and the frequency corresponding to the maximum amplitude exhibits a regular shift with increasing load.At the load condition of 750 MW,the dominant frequency inside the draft cone is 0.94 Hz,which is significantly different from other load conditions.Under the current computational setup,the simulation results agree well with the overall trend of the experiments,demonstrating a certain degree of reliability.This study provides valuable engineering insights into the cavitation flow characteristics and the evolution of pressure fluctuations in hydraulic turbines.