后置导叶对潮汐双向贯流式机组性能的影响

Effect of rear guide vanes on performance of tidal bidirectional tubular turbines

潮汐双向贯流式水轮机与常规贯流式水轮机的重要区别在于其需要兼顾正向和反向来流工况。为了均衡提升双向贯流式水轮机正反向运行条件下的性能,针对某潮汐双向贯流式水轮机,本文采用商业软件ANSYS CFX,研究了不同后置导叶位置和数量对双向贯流式水轮机性能及内部流动特性的影响。对比结果可知,后置导叶位置和后置导叶数量对机组反向发电时的性能影响较大,后置导叶安放位置系数为0.5和后置导叶数量为8时,机组总体性能较好。随着后置导叶数量增加,正向工况时尾水管水力损失减小,后置导叶通道水力损失反而增大;反向工况时转轮水力损失不断减小,转轮效率逐渐增大。研究成果为潮汐双向贯流式水轮机关键过流部件的优化设计提供技术参考。

Tidal bidirectional tubular turbines,unlike conventional units,need to consider both forward and reverse flow conditions.To balance and improve their performance under these two operating modes,this study investigates the effect of the position and number of different rear guide vanes on the performance and internal flow characteristics,using ANSYS CFX for flow simulations and taking a real project unit as a test case.The results show the position and number of these vanes have a great impact on the generating unit in reverse mode.The overall performance is better at a vane position coefficient of 0.5 and a vane number of eight.In forward mode,with the increase in the vane number,head loss decreases in draft tube but increases in rear vane channels;in reverse mode,the runner has a decreasing head loss and a gradually increasing efficiency.The results are useful for optimization design of the key flow components of tidal bidirectional tubular turbines.