基于弱可压的混流式水轮机流动特性数值研究  

Numerical study on flow characteristics of Francis turbines based on weak compressibility

作　　者：文强 郭鹏程 王钊宁[1] 孙龙刚 WEN Qiang;GUO Peng-cheng;WANG Zhao-ning;SUN Long-gang(Dongfang Electric Machinery Co.,Ltd.,Deyang 618000,China;Xi'an University of Technology,Xi'an 710048,China)

机构地区：[1]东方电气集团东方电机有限公司,四川德阳618000 [2]西安理工大学,陕西西安710048

出　　处：《水电站机电技术》2024年第8期9-14,143,共7页Mechanical & Electrical Technique of Hydropower Station

基　　金：陕西省创新能力支撑计划资助(2024RS-CXTD-31)。

摘　　要：高水头混流式水轮机由于水轮机上下游具有较高的压差,水流在高压力下呈弱可压缩性,影响机组内流特性的分布规律。为进一步探究弱可压缩性对水轮机压力脉动及涡流特性的影响,本文考虑水流的弱可压缩性,对Francis99高水头模型水轮机部分负荷流动特性开展非稳态数值研究。结果表明,在忽略和考虑可压缩两种模式下,水轮机无叶区及转轮内压力脉动信号脉动规律较一致。可压缩模式同时预测到尾水管内的低频高振幅和高频低振幅压力脉动信息,且与测试结果更为吻合,表明弱可压缩性对尾水管内流动信息的准确捕捉有重要影响。对压力信号进行同步和非同步分解后发现,表征涡带旋转的非同步分量主导了尾水管涡带的运动。进一步,考虑水流的可压缩性捕捉到的螺旋状尾水管涡带在整个演化周期内均显示为连续结构,且回流区与涡带位置相对应,表明涡带所占据的区域内主要由回流运动主导。Due to the high pressure difference between the upstream and downstream of high-head Francis turbines,the water flow exhibits weak compressibility under high pressure,which affects the distribution pattern of the internal flow characteristics of the units.To further investigate the influence of weak compressibility on pressure pulsation and vortex characteristics of turbines,this paper considers the weak compressibility of water flow and conducts an unsteady numerical study on part-load flow characteristics of the Francis99 high-head model turbine.The results indicate that the patterns of pressure pulsation signals in the bladeless area and the runner are quite consistent,whether compressibility is neglected or considered.When compressibility is considered,both low-frequency high-amplitude pressure pulsations and highfrequency low-amplitude pressure pulsations in the draft tube are predicted,closely aligning with the test results.This finding indicates that weak compressibility significantly influences the accurate capture of flow information in the draft tube.After the synchronous and asynchronous decomposition of pressure signals,it is found that the asynchronous component,which characterizes the rotation of the vortex rope,dominates the motion of the draft tube vortex rope.Furthermore,when water flow compressibility is considered,the captured helical vortex rope in the draft tube exhibits a continuous structure throughout the entire evolution cycle.The backflow zone corresponds to the vortex rope location,indicating that the area occupied by the vortex rope is primarily dominated by backflow motion.

关 键 词：尾水管涡带 可压缩性 压力脉动 回流 混流式水轮机 

分 类 号：TM312[电气工程—电机]