高含沙水流混流式水轮机磨蚀的数值预测与分析

为了研究高含沙水流混流式水轮机的磨蚀规律,应用SST k-ω湍流模型和Tabakoff磨蚀模型对渭河流域魏家堡水电站水轮机内部的多相流动及其磨蚀现象进行了数值模拟,预测了易发生磨蚀的部位并分析了产生磨蚀的原因.通过与电站实际运行后的水轮机磨蚀情况对比,数值模拟结果准确地预测了磨蚀发生的部位和磨蚀程度.数值模拟结果表明:磨蚀主要发生在蜗壳的隔舌、面与面连接的不光滑区域或缝隙等不规则的边界区域以及导叶和叶片的头部端面;壁面附近的流态对磨蚀有重要影响,磨蚀破坏最严重的区域为转轮出口靠近下环的叶片区域,此处的叶片弯曲的曲率较大,形成较高的速度和不稳定流动现象;尾水管中的弯肘段改变了流体的流动方向导致较为严重的磨蚀.研究成果为水轮机磨蚀的预防和抗磨蚀水轮机的优化设计提供了参考.

Numerical prediction and analysis of abrasion in a Francis turbine with high sediment concentration

To study the abrasion rule of Francis turbine with high sediment concentration, the SST k-ω turbulence model and Tabakoff abrasion model were employed to simulate the multiphase flow and sediment erosion phenomenon in the Francis turbine of Weijiabu Hydropower Station in the Weihe River area. The abrasive areas on different components were predicted and the causes of abrasion were analyzed. Compared with the turbine abrasion after operation of the power station, the numerical simulation results accurately predict the location and degree of abrasion. The numerical simulation results show that the erosion mainly occurs in the irregular boundary areas such as the tongue of the volute, the unsmooth area or gap of the surface-to-surface connection, and the leading edge of the guide vane and blade. The flow pattern near the wall has an important influence on erosion. The most serious erosion damage is the blade area near the down wear ring at the outlet of the impeller, where the curvature of the blade bending is large, forming a high speed and unstable flow phenomenon. The elbow of draft tube changes the flow direction of fluid, which leads to serious abrasion. The research results provide a reference for the prevention of turbine abrasion and the optimal design of anti-abrasion turbine.