Abstract
A gravitation vortex type water turbine is a new water turbine which generates power by the gravitational vortex which arises in a tank at the time of drainage. This water turbine has less environmental impact, such as ecosystem, it is possible to producing energy at low head and low flow rate. However, by changing the flow rate, it is believed to have a major effect on the performance of the water turbine. In this study, the performance and flow field in flow rate change were investigated by experiments and numerical analyses, and the following facts were clarified. As the flow rate increased, the power and the turbine efficiency was improved. In addition, at the runner inlet and outlet, the water region and the forward flow region of water region were expanded as the flow rate increased.
