冷却塔内小型混流式水轮机的设计及数值模拟

为减少冷却塔内小型混流式水轮机生产工艺过程的复杂性和较高的制造成本，以水动风机冷却塔内流量为3 000 t/h的小型混流式水轮机为研究对象进行结构设计。通过CFD对设计后的水轮机模型进行全流道三维定常湍流数值模拟，数值模拟中采用单方程Spalart-Allmars湍流模型，假定水流为不可压缩流体，不考虑能量方程，仅将质量守恒和动量守恒作为控制方程。结果表明，所设计的小型混流式水轮机整体流态较好，水力性能稳定，在设计转速149 r/min时，流量和出力均达到了驱动冷却塔内风机的要求，且水轮机效率较高。

Design and Numerical Simulation of Small Francis Turbine Used in Cooling Tower

In order to reduce the complexity and high cost of manufacturing process of small Francis turbine in cooling tower, the small Francis turbine with a flow of 3 000 t/h used in a hydraulic fan cooling tower is structurally designed as an object of research. For the sake of predicting performance of the Francis turbine, three-dimensional, steady turbulent flow is simulated in the entire flow passage based on CFD. In numerical simulation process, a single equation Spalart-Allmars turbulence model is adopted and it assumes that water is incompressible fluid as well as ignoring energy equation and only considering the N-S equations and the mass conservation equations as the control equations. The results show that the entire flow state is better and the hydraulic performance is in a stable state; especially, when the rotational speed is 149 r/min, the flow and the power output meet the requirements of driving the cooling tower fan, and the turbine has higher efficiency.