Effect of runner position on performance for open type cross-flow turbine utilizing waterfalls

The aim of this investigation is to develop an open type cross-flow turbine for environmental friendly nano-hydraulic turbine utilizing extra-low head waterfall. A relative position between the runner and the waterfall is one of the important factors for turbine efficiency. More often, it is necessary to precisely adjust this distance according to changes of the flow rate. In this study, we focused on the influence of the horizontal and vertical position of the runner on performance. First, the effect on the performance of the horizontal relative position between the runner and the falling water is verified. Next, two condition of the vertical relative position are concerned; one is the clearance between the runner and the water surface of the pool, the other is that between the runner and the solid surface as the runner placed closer to the ground or the riverbed. The result highlights that the horizontal relative position was an effect on the power performance. When the solid surface is presented under the runner, the performance is not effected when the water thickness is equivalent to 7.5% or more. On the other hand, when water surface is presented below the runner, the clearance between them has insignificant effect on the performance even though the runner underside is partly submerged.