以冷却塔内流量为5000t/h的超低比转速混流式水轮机为研究对象，通过结构设计，开发出了一种小型混流式水轮机，可直接与风机匹配，实现富余能量的回收。使用商业CFD软件Fluent，基于雷诺时均N-S方程、RNG k-ε湍流模型和SIMPLC算法，对设计的水轮机模型进行全流道三维定常湍流数值模拟，分析了水轮机内部流场及各部件的水力损失。结果表明，在设计工况下，水轮机的出力为143.3kW，效率为83.74%，水头损失较小；当富余水头在12～14m的范围内变化时，所给出的小型水轮机整体流态良好，水力性能稳定，效率均在83%以上，满足设计要求。

The turbine with super low specific speed and a flow rate of 5000 t/h used in a cooling tower was investigated through structural design in order to develop a new type of small Francis turbine that can match fan directly and recover the surplus energy from cooling tower. On the basis of Reynolds time-averaged N-S equation, RNG k-ε turbulent model, and SIMPLC algorithm, the three-dimensional steady turbulent flow in the designed turbine model was simulated numerically using the commercial CFD software Fluent, and the flow field in the turbine and hydraulic loss of each component were analyzed. The results showed that the output power of turbine is 143.3 kW and the efficiency is 83.74% with a small head loss under the design conditions. When the redundant head was in the range of 12 to 14 m, the turbine had a good flow state and stable hydraulic performance with the efficiency of above 83%, which indicated that the turbine meets the design requirements.