PIV Measurement of Flow Field around a Horizontally Installed Savonius Turbine in an Open Channel

Abstract

The development of a nano-hydro turbine that can effectively utilize the wasted hydro energy in infrastructure such as agricultural and industrial channels and irrigation waterways, will expand the available area as small hydro energy. Up to this time, the utilization of such a small hydropower has not progressed owing to economic reasons. Therefore, we focus on the Savonius type, which has the advantages of low manufacturing cost and excellent maintainability because of its simple structure. Conventionally, the Savonius type has been developed and researched as a vertical axis wind turbine. To effectively utilize the water surface flow, which is particular to open channels, we place the turbine runner perpendicular to the water flow and horizontally on the channel bottom. In our previous study, we experimentally investigated the effect of the turbine installation condition, which specifies the distance between a runner and the water surface, on the performance at each water level. As a result, it was clarified that there is a suitable turbine installation height for each water flow condition such as water level. Therefore, in this study, we visualized the flow fields paticular to Savonius type runners such as attached flow and dragging flow by PIV measurement and investigated the mechanism by which the turbine installation height brings about a difference in torque characteristics.