抄録
A gravitation vortex type water turbine is a water turbine which generates power by the gravitational vortex. Although this water turbine can be generated by a low head and a smallness flow, the flow field is a complicated thing which has a free surface. We researched effect of flow rate on performance and hydraulic loss of a gravitation vortex type water turbine using loss analysis. However, effect of number of blades on hydraulic loss has not been elucidated. In this study, we performed the free surface flow analysis of the gravitation vortex type water turbine and applied the loss analysis method proposed in the past to changes in the number of blades. Then, we also examined the causes and mechanisms of the losses. As the results, the following facts were clarified. Among the hydraulic losses, tank loss and tank outlet loss were dominant.
The larger the number of blades, the smaller the tank outlet loss, and the difference in the tank outlet loss due to the difference in the number of blades greatly affected the difference in turbine output and turbine efficiency.
