バルブ水車ドラフトチューブの圧力損失に及ぼす旋回強さの影響

抄録

The draft tube of bulb turbines, which is a diffuser to convert kinetic energy into static pressure by decelerating the flow, plays an important role in turbine efficiency. The flow in draft tubes is characterized by the swirl flow at the runner outlet. In order to estimate the effect of swirl intensity on the total pressure loss in the draft tube of the bulb turbine, full-model simulations that include whole hydraulic components are compared to results obtained from the model test. The simulation results show the swirl intensity is an effective parameter for prediction of turbine efficiency. In addition, using the relation between the swirl intensity and the total pressure loss obtained from full-model simulations, single-passage simulations of the runner are able to predict the efficiency of the bulb turbine with the draft tube.