混流式水轮机大负荷压力脉动模型试验研究  

Experimental study on large-load pressure pulsation model of Francis turbine

作　　者：吴金荣 郑志太 徐洪泉[2] 廖翠林[2] 张驰也 WU Jin-rong;ZHENG Zhi-tai;XU Hong-quan;LIAO Cui-lin;ZHANG Chi-ye(Huadian Ningde Power Development Co.,Ltd.Ningde 352100,China;China Institute of Water Resources and Hydropower Research,Beijing 100038,China)

机构地区：[1]华电宁德电力开发有限公司,福建宁德352100 [2]中国水利水电科学研究院,北京100038

出　　处：《水电站机电技术》2021年第5期1-6,26,111,共8页Mechanical & Electrical Technique of Hydropower Station

基　　金：中国水利水电科学研究院科研专项(HM0145B432016)。

摘　　要：混流式水轮机涡带压力脉动是引起水电机组剧烈振动的主要水力因素之一,其关注重点是低负荷偏心涡带,对大负荷直涡则研究较少。但是,在部分水电站大负荷压力脉动很严重,有的甚至引起尾水管底板撕裂、转轮掉块等问题,严重影响电站运行安全。本文重点介绍了某混流式模型水轮机进行大负荷压力脉动试验的方法及结果。试验过程中,在测量压力脉动的同时观测记录了尾水管内流态,并选择部分大负荷工况进行了变空化系数试验。试验发现,在混流式水轮机大负荷工况,尾水管涡带均为直涡;单位流量越大,涡带空腔直径越大,压力脉动幅值越大;单位转速越高,涡带空腔直径越小,压力脉动幅值却越大;最大幅值多发生在内顶盖测点。随空化系数降低,涡带空腔直径增大,压力脉动幅值增加,低空化系数的峰值可达能量工况幅值的10多倍。本文还应用空化空腔危害水力机械稳定性理论及自由涡原理分析了尾水管涡带在大负荷工况均为直涡的原理,并结合观测结果论证分析了叶道涡对高单位转速、大流量工况压力脉动的影响,指出直涡和叶道涡是造成大负荷压力脉动幅值攀升的两个关键因素。Mixed-flow turbine vortex band pressure pulsation is one of the main hydraulic factors causing severe vibration of hydropower units.Most attention is focused on low-load eccentric vortex belt.Less research had been done on large-load straight vortex.However,the pressure pulsation of large load in some hydropower stations is serious,and some of them even cause problems such as tearing of tail pipe bottom plate and falling of runner block,which seriously affects the safety of power station operation.This paper focuses on the method and results of a mixedflow model hydraulic turbine for large-load pressure pulsation test.The test measured the pressure pulsation while observing and recording the flow pattern in the tail pipe,and selected some large load conditions for the variable cavitation coefficient test.It is found that the vortex belt of the tail pipe is straight vortex in the large load condition of the mixed-flow turbine;the larger the unit flow rate,the larger the diameter of the vortex belt cavity,the larger the amplitude of pressure pulsation;the higher the unit speed,the smaller the diameter of the vortex belt cavity,the higher the amplitude of pressure pulsation;the largest amplitude occurs mostly at the measurement point of the inner top cover.As the cavitation coefficient decreases,the vortex cavity diameter increases,and the pressure pulsation amplitude increases,and the peak value of low cavitation coefficient can reach more than 10 times of the energy working condition amplitude.This paper also applies the cavitation cavity hazard hydromechanical stability theory and the free vortex principle to analyze the principle that the vortex belt of the tail pipe is straight vortex at high load conditions,and combines the observation results to argue and analyze the influence of the vortex of the lobe channel on the pressure pulsation at high unit speed and high flow conditions,pointing out that the straight vortex and the vortex of the lobe channel are the two key factors causing the pressure pulsation ampl

关 键 词：混流式水轮机 大负荷 压力脉动 直涡 叶道涡 

分 类 号：TK733.1[交通运输工程—轮机工程]