摘要
为研究空化条件下水泵水轮机的压力脉动特性,采用RNGk-ε湍流模型和Schnerr-Sauer空化模型,对某抽水蓄能电站模型机进行了全流道非定常空化流动数值计算.结合试验数据,针对机组处于不同空化阶段时的压力脉动特征进行了分析.结果表明:随着空化系数的改变,各个位置的频率成分几乎保持不变,幅值大小则受到了较为显著的影响.蜗壳进口的压力脉动主频以低频成分为主,幅值相差不大.导叶后转轮前无叶区的压力脉动主频为转轮转频,同时存在着叶频及倍频,幅值随空化系数的降低而逐渐增大.尾水管内的压力脉动主频皆为涡带的转动频率,随着空化系数的降低,尾水管进口和锥管上游的脉动幅值呈先迅速上升到最大值而后逐渐下降的趋势;当空化系数为极低时,幅值往往都会有所下降,但此时尾水管区接近于断流状态,对机组的安全稳定性是十分不利的.
In order to study the reversible pressure fluctuation characteristics of pump-turbine under cavitational condition,numerical simulation of unsteady cavity flow within entire flow passage of modeled unit in a pumping storage plant was carried out by using RNGk-εturbulence mode and Schnerr-Sauer cavitation model.With the help of its test data,the feature of pressure fluctuation of the unit at different cavitation stages was analyzed.The result showed that with the change of the cavitation coefficient,the frequency components at each unit position would be almost unchanged,and the amplitude would be significantly affected.The principal frequency pressure fluctuation at the inlet of the spiral case would mainly be dominated by low frequency components and the difference of amplitude would be small.The principal frequency of the pressure fluctuation at the vaneless area between guide vances and rotor would be the rotational frequency of the rotor.At the same time,there would exist the blade rotation frequency and frequency doubling.The amplitude would gradually increase with the decrease of the cavitation coefficient.The principal pressure fluctuation frequency in whole draft tube would be the rotational frequency of the vortex band.With the decrease of the cavitation coefficient,the fluctuation amplitude at the inlet of the draft tube and the upstream of the conic tube would increase rapidly to its maximum at first and then decrease gradually.When the cavitation coefficient is extremely low,the amplitude would often tend to decline somewhat.At this moment,the flow at draft tube area would approach to its cut-off state.This would be very detrimental to the safety and stability of the unit.
作者
李琪飞
刘超
李仁年
韩伟
王源凯
LI Qi-fei 1,2 , LIU Chao 1 , LI Ren-nian 1,2 , HAN Wei 1,2 , WANG Yuan-kai 1(1. College of Energy and Power Engineering, Lanzhou Univ. of Tech., Lanzhou 730050, China;2. Key Laboratory of Fluid Machinery and Systems of Gansu Province, Lanzhou Univ. of Tech., Lanzhou 730050, Chin)
出处
《兰州理工大学学报》
CAS
北大核心
2018年第3期50-56,共7页
Journal of Lanzhou University of Technology
基金
国家自然科学基金(51566009)
甘肃省自然科学基金(1310RJZA023)
关键词
水泵水轮机
部分负荷
空化流动
压力脉动
数值模拟
pump-turbine
partial load
cavitation flow
pressure fluctuation
numerical simulation
