分流叶片对混流式水轮机泥沙磨损特性影响的数值研究  

Numerical Investigation of Influence of Splitter Blades on Hydraulic Performance and Sediment Wear Characteristics of Francis Turbines

作　　者：周鹏 孙淑贞 郭鹏程[2] 师孟悦 安栋栋 孙龙刚 Zhou Peng;Sun Shuzhen;Guo Pengcheng;Shi Mengyue;An Dongdong;Sun Longgang(Shaanxi Provincial Dongzhuang Water Conservancy Engineering Co.,Ltd,Xi'an 713200,China;School of Water Resources and Hydroelectric Engineering,Xi'an University of Technology,Xi'an 710048,China)

机构地区：[1]陕西省东庄水利枢纽工程建设有限责任公司,西安713200 [2]西安理工大学水利水电学院,西安710048

出　　处：《水动力学研究与进展（A辑）》2024年第5期767-776,共10页Chinese Journal of Hydrodynamics

基　　金：陕西省水利厅科技计划项目(2023slkj-3)。

摘　　要：在含沙水流条件下运行的水轮机,泥沙颗粒易引起过流部件材料磨损破坏、诱发不稳定流动甚至机械振动,严重影响电站的安全稳定运行及经济效益。该文采用基于颗粒输运模型耦合修正的Oka壁面侵蚀模型,联合SSTk-ω湍流模型对原始混流式水轮机和转轮增加分流叶片的新水轮机方案分别开展水沙两相数值研究,以探究分流叶片对水轮机泥沙磨损特性及水力性能的影响,其中Oka壁面侵蚀模型通过修改速度指数及冲击角常数以获取更准确的壁面磨损特性。研究发现,增加分流叶片后,在90%、65%和40%额定负荷工况下,水轮机的水力效率分别提升0.3%、0.5%和0.2%。转轮叶片吸力面头部及叶片出水边附近的相对速度被降低,40%额定负荷工况下,转轮叶道中靠近压力面的旋涡结构被显著抑制。原始转轮叶片最大的泥沙侵蚀率发生在叶片出水边靠近下环附近,且随负荷的减小,叶片压力面磨损强度逐渐降低,而吸力面不同工况之间的侵蚀强度比较接近。采用分流叶片的新转轮方案,叶片表面磨损率均显著降低,这与转轮内流动结构改善,泥沙颗粒对转轮叶片的撞击速度降低有关。该文揭示了分流叶片对水轮机内部流动及磨损特性的改善作用机制,可为水轮机抗泥沙磨损优化提供参考。The challenge of wear induced by sediment stands as a focal concern during the operation of hydraulic turbines subjected to sediment-laden water flows.Wear of the flow passage components can lead to material losses,induce unstable flow,and even trigger mechanical vibrations,significantly impacting the safety,stability,and economic performance of the power stations.This study,based on particle transport model coupled with the modified Oka wall erosion model,employing numerical simulation techniques for two-phase water-sand flow,investigates the erosion characteristics of a high-head Francis prototype turbine equipped with an original runner and a runner enhanced with added splitter blades,the Oka wall erosion model is improved by modifying velocity index and the impact angle constant to obtain more accurate wall wear characteristics.The investigation reveals that under load conditions of 90%,65%,and 40%of the rated capacity,the hydraulic efficiency of the turbine with added splitter blades improves by 0.3%,0.5%,and 0.2%,respectively.In addition,the relative velocity near the head of the suction surface of the runner blade and the water outlet of the blade is reduced,and the vortex structure close to the pressure surface in the runner blade is significantly suppressed under the condition of 40%rated load.The maximum sediment erosion rate of the original runner blade occurs near the water outlet of the blade near the lower ring,and the wear intensity of the pressure surface of the blade gradually decreases with the decrease of load,while the erosion intensity between different working conditions of the suction surface is relatively close.The wear rate of the blade surface is significantly reduced by the new runner scheme of the split blade,which is related to the improvement of the flow structure in the runner and the reduction of the impact velocity of sediment particles on the runner blade.The study elucidates the mechanism by which splitter blades enhance the internal flow and wear characteristics of the turbine,

关 键 词：泥沙磨损 分流叶片 撞击速度 混流式水轮机 

分 类 号：TV734.1[水利工程—水利水电工程]