导叶开度对混流式水轮机压力脉动特性及流动诱导噪声的影响

摘要：为研究导叶开度对混流式水轮机压力脉动特性及流动诱导噪声的影响，应用CFD和LMS Virtual Lab软件分别对混流式水轮机在三种导叶开度下进行非定常流场和声场数值计算。结果表明：混流式水轮机内压力脉动主要受到叶片通过频率（10833 Hz）以及低频脉动（415 Hz）的影响；随着导叶开度的增大，叶频对转轮进口和蜗壳内压力脉动的影响逐渐增加；外场噪声的分布与混流式水轮机的几何轮廓相吻合；尾水管弯肘段有助于减弱混流式水轮机流动噪声声压；导叶开度越大，混流式水轮机辐射出的外场噪声声压值越大，偶极子特性越明显。研究结果可为混流式水轮机组的稳定运行及流动诱导噪声的控制提供参考。

关键词：混流式水轮机；导叶开度；压力脉动；流动诱导噪声；数值计算

中图分类号：TV742 文献标志码：A 文章编号：

16721683（2018）05018607

The influence of guide vane opening on pressure pulsation characteristics and flowinduced noise in Francis turbine

WANG Haolan1，ZHENG Yuan2，SUN Aoran1，ZHANG Fulin1，GAO Chenghao1，ZHOU Ying1

（

1.College of Water Conservancy and Hydropower，Hohai University，Nanjing 210098，

China；2.Institute of Innovation，Hohai University，Nanjing 210098，China）

Abstract：

In order to study the influence of different guide vane openings on the pressure pulsation characteristics and flowinduced noise in Francis turbine，we used CFD and LMS Virtual Lab software to calculate the unsteady flow field and sound field in a Francis turbine under three guide vane opening degrees.The results showed that the pressure pulsation in the Francis turbine was mainly affected by the rotation frequency of blade （10833 Hz） and the lowfrequency pressurepulse （415 Hz）.With the increase of the guide vane opening，the influence of blade frequency on the pressure pulsation in the inlet of the runner and the volute would gradually increase.The distribution of outfield noise accorded with the geometric contour of the Francis turbine.The elbow section of the draft tube was helpful for the attenuation of the flowinduced noise of the Francis turbine.The greater the guide vane opening，the greater the sound pressure of the external noise generated by the Francis turbine，and the more obvious the dipole characteristics.The research results can provide a reference for the stable operation of Francis turbine and the control of flowinduced noise.

Key words：

francis turbine；guide vane opening；pressure pulsation；flowinduced noise；numerical calculation

混流式水轮机由于应用水头广、运行稳定效率高，被广泛应用[1]。随着国家水电开发技术日益成熟，对水能资源利用的最大化，水力机组容量迅速增大，水力设备的运行稳定性成为水电事业发展的阻碍，如机组运行过程中的压力脉动、振动、噪声现象[27]。

国内外学者对水轮机压力脉动进行了相关研究。刘树红等[8]采用数值模拟与模型试验相结合的方法，分析了混流式水轮机内部非定常流动，结果表明转轮与活动导叶间的动静干扰以及尾水管内涡带是产生压力脉动的两个主要脉动源，并在整个水轮机流道内传播；季斌等[9]采用三维非定常湍流模拟的方法，探讨压力脉动在转轮内的传播规律，结果表明叶片表面的低频脉动由叶片出口到进口逐渐衰减，而高频脉动由叶片进口到出口逐渐衰减。文献[1014]通过数值模拟技术对水轮機尾水管涡带进行探讨，结果表明随着导叶开度由小变大，尾水管涡带经历了由双螺旋到单螺旋再到柱状涡的变化过程，加长泄水锥、在尾水管内安装阻尼栅或者导流板等措施均可在一定程度上消除尾水涡带。郑源[15]等对混流泵进行非定常数值计算，结果表明混流泵产生流动诱导噪声的主要原因是叶轮和蜗壳之间的动静干涉，压力脉动的主频和泵体的固有频率决定了流动诱导噪声的主频。文献[1623]等对轴流泵、离心泵进行流动噪声数值模拟，提出降低噪声的措施。