尾水管扩散段结构变化对低水头混流式水轮机性能的影响

为探究低水头混流式水轮机尾水管扩散段底板抬起角对其性能的影响,结合西南某水电站增效扩容项目,在保证尾水管扩散段上下面角度不变的前提下,拟定了两套扩散段底板抬起角方案,利用相关软件建立了高效区内导叶开度为35°时水轮机的水体模型,并对其进行了流场数值模拟。结果表明,尾水管扩散段底板抬起角对水轮机效率影响不大,对水轮机出力和尾水管回能系数影响较大;随着底板抬起角的增加,相同水头下水轮机出力逐渐减小;在低水头(小流量)时,有适当的底板抬起角比没有时更有利。

Impact of Change Structure of Draft Tube Diffuser on Performance of Low Head Francis Turbine

In order to explored the influence of diffuser bottom plate raised angle of draft tube on performance of low head francis turbine, combined with the synergistic expansion project of a certain hydropower station in Southwest China, two bottom plate raised angle schemes of draft tube diffuser are proposed on the premise of ensuring constant angle between top and bottom surface. In high efficiency region, at the operating condition of 35° guide vane opening, hydraulic turbine water model of the whole flow passage is established by using related software. And then it has carried out the numerical simulation of flow field. The results show that the bottom plate raised angle of draft tube diffuser has little impact on turbine efficiency while it has impact on turbine output and draft tube recovery coefficient greatly; along with the increase of the bottom plate raised angle, turbine output decreases under the same head; in the condition of low head (low flow), the suitable bottom plate raised angle is better for turbine operation.