水力发电2025，Vol.51Issue(4)：69-74,6.
巨型混流式水轮机小流量工况下高保真数值模拟
Numerical Simulation on the Flow Characteristics of Giant Francis Turbine under Low Flow Rate Condition
摘要
Abstract
Due to the participation of hydropower units in deep peak regulation of power grid,the operation probability of conventional Francis turbine under low flow condition increases sharply.The flow characteristics under low flow rate conditions are worthy of further investigation.A three-dimensional refined numerical simulation of the entire flow channel of a giant Francis turbine is conducted using a DES turbulence model.The evolution characteristics of flow patterns,vortex in blade passage,vortex rope in draft tube,and pressure fluctuation of the unit under four low flow rate conditions are investigated.The results show that the scale of blade vortex decreases with load increase,and at the 500 MW operating condition,the tubular blade vortex basically disappears.During low flow rate condition,a obvious circumferential vortex rope is formed near the wall surface of the straight cone section of draft tube,and in the process of flow downstream,it continuously splits into small-scale vortex ropes and spreads towards the center of draft tube with the gradual decrease of flow speed.However,at 500 MW operating condition,the circumferential vortex rope on the side wall disappears,and a relatively stable vortex rope is formed at the center of draft tube,causing an increase in the amplitude of pressure pulsation.Due to the influence of vortex rope and rotating interference,the pressure fluctuations of 0.2 times,0.5 times,15 times and 30 times rotating frequency of runner can be detected in the region between the runner blades and guide vanes.Under the low flow rate conditions,the high amplitude pressure pulsation frequency in the draft tube is concentrated at 0.2-0.5 times rotating frequency of runner,and the pressure pulsation frequency band presents a wide range(up to 5 times rotating frequency),and with the increase of power,the frequency band shows a trend of gradual contraction.关键词
混流式水轮机/长短叶片/小流量工况/叶道涡/尾水涡带/压力脉动/数值模拟Key words
Francis turbine/long and short staggered blades/low flow rate condition/vortex in blade passage/vortex rope in draft tube/pressure pulsation/numerical simulation分类
水利科学引用本文复制引用
易万爽,薛炳,宋晶辉,徐波,王文全,杜娟..巨型混流式水轮机小流量工况下高保真数值模拟[J].水力发电,2025,51(4):69-74,6.基金项目
长江电力股份有限公司资助项目(Z152302017) （Z152302017）
