文章摘要
混流式水轮机发电转空载工况转轮特性研究[1]
Research on the Runner Characteristics of Francis-turbine under Power Generation to No-load Condition
投稿时间:2024-03-16  修订日期:2024-04-25
DOI:
中文关键词: 混流式水轮机  转轮  发电转空载工况  湍动能  振动模态
英文关键词: Francis-turbine  runner  power generation to no-load condition  turbulent kinetic energy  vibration mode.
基金项目:国家自然科学青年基金(51909222);陕西省博士后特别资助项目(2023BSHTBZZ22);中国水力发电学会第二届“青年人才托举”项目(CSHE-YESS-2024006);国家留学基金委项目(No.202206305003)。
作者单位邮编
毛秀丽* 西北农林科技大学 712100
陈星锟 西北农林科技大学 
尹进步 西北农林科技大学 
苟文涛 西北农林科技大学 
刘志明 西北农林科技大学 
何军龄 西北农林科技大学 
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中文摘要:
      随着水电站逐步转向调荷运行,水轮机过渡工况运行时长增加将严重影响转轮性能。本文针对发电转空载过渡工况,以某混流式水轮机为研究对象,采用SST k-ω湍流模型与流固耦合方法分别求解内流与结构特性。研究结果表明:转轮内水流压力脉动频率为导叶、叶片频率的倍数,且在发电转空载过程中转轮内各监测点的30fn、60fn脉动幅值相近,幅值范围随着导叶关闭而逐渐缩小;转轮内涡旋结构主频为64fn、68fn,其脉动能量沿流线减小,随着转轮进口来流角α的减小,进水边压力面流动分离现象加剧,进一步出现绕流形成马蹄涡和高TKE区域,涡旋体积随负荷持续减小而先增后减的趋势;0.4QBEP时叶道涡延伸至转轮出口侧,且在t=7s时(0.2QBEP)涡核分裂,各叶间涡连成片状阻塞流道。结构方面:偏离设计工况使得来流撞击叶片进水边导致等效应力的增加,叶间流场马蹄涡位置与低等效应力区相对应。因涡核分裂与尾水管进口空腔旋涡双重作用,转轮出口边出现最大的等效应力(4MPa)与变形量(4.3μm)。内流与结构关联上:转轮进口Z1区的等效应力与转矩、流量成线性关系,而Z2、Z3区为三次函数。此外,变形量在负荷主导区与力矩、流量亦成线性关系,在回流主导区是二次函数关系。
英文摘要:
      As hydropower stations gradually shift to load-regulated operation, the increase in the operating operating time of turbine in transitional conditions will seriously affect runner performance. This paper aims at studying the fluid-solid coupling correlation characteristics of runner, wherein SST k-ω turbulence model and the fluid-solid coupling method are applied to solve the flow field and structural field, respectively. The results show that the main frequencies of pressure fluctuation in the runner are pass frequencies of blades and guide vanes, as well as their multiple frequencies. The pressure fluctuation frequencies of all monitoring points in the runner have similar amplitudes at 30fn and 60fn, and the amplitude range gradually narrows as the guide vanes close. 64fn and 68fn are the main frequencies of vortex structures in the runner, which pulsation energy attenuates along the streamlines. The blade passage vortex reaches the runner outlet at 0.4QBEP, the vortex volume in the runner first increases and then decreases as the load continues to reduce. After 0.4QBEP, the flow separation phenomenon on the pressure surface at the inlet of runner intensifies as the decrease of α(the absolute velocity angle), further horseshoe vortex with high turbulent kinetic energy appears in the flow channels, which is accompanied with flow around blade outlet. The vortex core at runner outlet start to split at t=7s (0.2QBEP), then vortices in each runner passage form sheets and block the flow channel. In the structural field, the increase of equivalent stress at blade inlet is caused by the flow impact with smaller α, the horseshoe vortices in runner channels correspond to long and narrow zones with low equivalent stress. The equivalent stress(4MPa) and deformation(4.3μm) at the runner outlet are the maximum, because of dual effects from vortex core splitting at runner outlet and cavity vortices in the straight section of the draft tube. Last but not least, it founds that the equivalent stress has a linear relationship with torque and flow in Z1, whereas it is cubic functions in Z2 and Z3. The deformation is also has a linear relationship with torque and flow in the load-dominated area, while it is a quadratic function in the return-dominated area. The above relationships between flow field and structure field need further validation in other hydraulic machinery, it is the next work for the authors.
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