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| Numerical simulation of hydraulic turbines with forward-curved blades |
| LIU Yingying, YANG Sunsheng, KONG Fanyu, WANG Tao, CHEN Kai |
| National Research Center of Pumps, Jiangsu University, Zhenjiang, Jiangsu 212013, China |
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Abstract The impellers of centrifugal pumps with three different specific speeds were designed with forward-curved blades to study their performance as turbine. Then, the whole internal flow filed in these hydraulic turbines were calculated with structured mesh technique. The performance curves, pressure and velocity fields at different flow rates were analyzed, and the variation of flow field in the impeller and draft tube with flow rate was obtained. The results show that the fluid pressure steadily decreases from the volute inlet to the impeller and draft tube outlet, and the pressure difference between the inlet and the outlet of hydraulic turbine increases gradually with increasing flow rate. A vortex region is found near the blade pressure side, and its position and size vary with flow rate. There is a peripheral velocity component in the cross-section of draft tube, its magnitude varies with flow rate. The hydraulic loss inside a hydraulic turbine with forward-curved blades mainly occurs in the impeller and accounts for more than 60% of the total hydraulic loss for three hydraulic turbines, further the percentage rises with increasing specific speed. Therefore, the optimization design of hydraulic turbine with forward-curved blades should be focused on the impeller.
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Received: 20 June 2016
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