超低水头竖井贯流式水轮机转轮数值模拟优化

Numerical simulation and optimization of shaft tubular turbine runner with super-low head

结合江苏苏北某电站,研究开发了一种设计水头为2 m左右的超低水头竖井贯流式水轮机.基于Navier-Stokes方程,采用SIMPLEC算法对该竖井贯流式水轮机全流道三维定常不可压湍流流场进行了数值模拟,分析了超低水头转轮叶片翼形、直径及安放角对水轮机性能的影响.分析了多个方案的水力性能,选出了最佳的水轮机转轮.结果表明:在满足电站设计要求的情况下,翼型优化后,转轮直径为1.75 m、叶片安放角为23°时的水轮机,在效率、水力损失等方面都表现出最佳的性能:该超低水头竖井贯流式水轮机在导叶开度为65°,设计水头为2.1 m时,数值模拟出的流量为10.05 m3/s,效率最高为87.6%.以GD-WS-35水轮机模型试验研究该水轮机的能量性能,在设计工况下,对数值模拟效率最高的水轮机方案试验的结果:模型装置的流量为0.398 m3/s,效率为83.34%;按原模型转换规律转换为原型装置数据,则流量为9.96 m3/s,效率为85.14%;数值模拟效率比模型试验效率的结果略高,误差范围为±3%.

For a hydropower station in North Jiangsu province, a shaft tubular turbine with about 2 m super low head was developed to effectively make use of low head hydro resources. The three-dimen- sional, steady, turbulent flow in the flow passage of the turbine was numerically simulated by using the Navier - Stokes equations and the SIMPLEC algorithm, and the influences of vane section profile, run- ner diameter and stagger angle on the turbine performance were analyzed. Eventually, an optimal run- ner was specified by comparing the performance of different design cases. The results showed that after optimization the turbine with 1.75 in diameter and 23 o stagger angle not only has met the design re- quirements by the hydro-power station but also exhibits the best efficiency and the highest output po- wer. At the design point （head 2.1 m, flow rate 10 m3/s） , the turbine efficiency is 87.6%. Based on the optimized turbine a model turbine GD - WS - 35 was made and its performance was measured in laboratory. Under the design condition （flow rate 0. 398 m3/s） , the best efficiency of the model was 83.34%. By applying the scaling law of hydro-turbine, the peak efficiency of the prototype of thismodel will be 85.14% at the flow rate of 9.96 m3/s. The CFD predicted peak efficiency is slightly higher than experimental one, suggesting the error is within ±3% range.