Indexed on: 23 May '13Published on: 23 May '13Published in: Journal of Mechanical Science and Technology
The transient power failure process of a prototype pump-turbine was studied numerically by three-dimensional (3-D) simulations. Fluid coupling and dynamic mesh (DM) method were used to calculate the rotational speed of the runner. Simulations were performed based on turbulence model. Specific transient characteristics, such as the flow rate, head, rotational speed, were analyzed. The pumpturbine had a minimum head and a maximum axial force when the flow rate was 0 during the transient process. Pressure fluctuations increased when the pump-turbine ran at pump braking mode. Reverse flow in the casing as well as stall phenomenon in the runner had a great effect on the change of head. Pressure in the runner was greatly reduced when the pump-turbine ran at pump braking mode. The computational method could be used to interpret the abnormal phenomenon by the analysis of flow mechanism during a transient process.