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

作　　者：易万爽 薛炳 宋晶辉[1,2] 徐波 王文全[3,4] 杜娟 YI Wanshuang;XUE Bing;SONG Jinghui;XU Bo;WANG Wenquan;DU Juan(China Yangtze Power Co.,Ltd.,Yichang 443002,Hubei,China;Hubei Technology Innovation Center for Smart Hydropower,Wuhan 430010,Hubei,China;State Key Laboratory of Hydraulics and Mountain River Engineering,Sichuan University,Chengdu 610500,Sichuan,China;College of Water Resources and Hydropower,Sichuan University,Chengdu 610500,Sichuan,China)

机构地区：[1]中国长江电力股份有限公司,湖北宜昌443002 [2]湖北省智慧水电技术创新中心,湖北武汉430010 [3]四川大学山区河流保护与治理全国重点实验室,四川成都610500 [4]四川大学水利水电学院,四川成都610500

出　　处：《水力发电》2025年第4期69-74,共6页Water Power

基　　金：长江电力股份有限公司资助项目(Z152302017)。

摘　　要：由于水电机组参与电网深度调峰,常规混流式水轮机在小流量工况下运行的概率急剧增加,小流量工况下的流动特性值得深入研究。通过DES湍流模型对某巨型混流式水轮机进行全流道三维精细化数值模拟,分析了机组在4种小流量工况下的内部流态、叶道涡、尾水涡带及压力脉动的演化特性。结果表明,随着负荷增加,叶道涡的尺度呈降低趋势,在500 MW的工况,管状叶道涡基本消失。在小流量运行时,尾水管直锥段近壁面附近形成明显的环向贴壁涡绳,在向下游进动过程中,随着速度逐渐降低,不断分裂成小尺度的涡绳,并向尾水管中心扩散,但至500 MW时,边壁环向涡绳基本消失,尾水管中心处形成较为稳定的螺旋进动涡带,造成压力脉动幅值的增加。受尾水涡带和动静干涉的影响,转轮与导叶间无叶区可以监测到0.2倍频、0.5倍频、15倍频和30倍转频的压力脉动。小流量工况下尾水管内高幅值压力脉动频率集中在0.2~0.5倍频,且总体上呈现较宽压力脉动频带(达到5倍转频范围),并随功率增加,频带范围呈现逐渐收缩的趋势。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 

分 类 号：TV734.1[水利工程—水利水电工程] TK79[动力工程及工程热物理—流体机械及工程]