混流式水轮机停机时瞬态尾水管流场与压力脉动的数值分析  

Numerical analysis of transient flow field and pressure fluctuation in draft tube during shutdown of Francis turbine

作　　者：苏立 毛成 沈春和 文贤馗 SU Li;MAO Cheng;SHEN Chun-he;WEN Xian-kui(Electric Power Research Institute of Guizhou Power Grid Co.,Ltd.,Guiyang 550002,China)

机构地区：[1]贵州电网有限责任公司电力科学研究院,贵阳550002

出　　处：《广西水利水电》2023年第2期78-83,共6页Guangxi Water Resources & Hydropower Engineering

基　　金：贵州省科技支撑计划项目(黔科合支撑[2020]2Y042)。

摘　　要：为了研究汽轮机停机引起的压力波动和流场不稳定性,本文基于k-ε湍流模型开展了额定工况下混流式水轮机停机过程中瞬态尾水管流场的数值研究,分析研究了水轮机流域内部的压力波动和非定常流动不稳定性的原因。研究表明:水轮机停机过程中的压力波动分为3个阶段,第一阶段仍存有较高瞬时压力波动,整体压力均值持续减小;第二阶段压力振幅在稳步下降、整体压力回升;第三阶段压力稳定并且不再波动,尾水管中小尺度涡结构增加且不断溃灭坍塌,最后消失达到稳定流动;通过尾水管内速度场的变化,对停机期间涡结构的形成和变化作出了深入的解释,有助于了解和预防水轮机停机过程所导致的破坏性后果。In order to study the pressure fluctuation and flow field instability caused by turbine shutdown,numerical study of transient flow field in draft tubed during shutdown of Francis turbine from rated operating condition was car⁃ried out based on k-εturbulence model.The causes for pressure fluctuation and unsteady flow instability in turbine hydraulic passage were analyzed and studied.The results of study show that the pressure fluctuation during the shut⁃down process of hydraulic turbine can be divided into three stages.At the first stage,there is still high instantaneous pressure fluctuation,and the average value of the overall pressure continues to decrease;at the second stage,the pressure amplitude decreases steadily and the overall pressure rises again;at the third stage,the pressure is stable and no longer fluctuates,and small-scale vortex structure in the draft tube increases and collapses continuously,and finally disappears to achieve a steady flow.Through the change of the velocity field in the draft tube,an in depth explanation is made on the formation and change of the vortex structure during the shutdown period,which is helpful to understand and prevent the destructive consequences caused by the shutdown process of the hydraulic turbine.

关 键 词：混流式水轮机 瞬态运行 停机过程 涡流场 压力脉动 

分 类 号：TK733[交通运输工程—轮机工程]