拡大流路への自然吸気による圧力低下及び動力損失抑制方法に関する研究

抄録

In a cross-flow turbine downstream side in the flow channel between the lower nozzle wall and the guide vane is a divergent nozzle under small guide vane opening condition. In a divergent nozzle, energy loss happens due to both the occurrence of flow separation and an increase in turbulence in the case of a large expanding ratio. In addition, the turbine cannot be applied in a high head because an increase in the flow velocity causes cavitation at the narrow section in the divergent nozzle. Therefore, the authors propose an energy loss suppression method using air sucked naturally through a hole drilled on the wall upstream of the divergent nozzle. This study confirmed by using CFD that the air sucked causes water flow separation from the wall, thereby reducing the ratio of water power loss to the power at the inlet, and pressure drop decreasing at narrow section. Also, it was confirmed that the total pressure in the jet downstream of the nozzle almost corresponds to the results obtained using the experiment.