Effect of flow condition on undershot water wheel performance

This study focused on the development of an undershot open cross-flow turbine that is applicable in extremely low head hydropower conditions, especially in rapid and shallow streams such as agricultural waterways in mountain areas. A model of the cross-flow turbine was constructed and examined experimentally. The authors evaluated the effect of the flow conditions on undershot wheel power performance. The effect of the number of blades and the blade thickness on runner performance was also investigated. It was found that the power coefficient changed drastically with varying impinging flow thickness and runner installation height. Power could be generated when the impinging flow thickness was less than 28% of the runner diameter. The maximum power coefficient, CPmax, increased as the impinging flow thickness was decreased. Furthermore, a higher CPmax was obtained as the runner installation height was lowered. This was because the water flow was inclined between the runner and the bottom wall of the channel. In this study, the highest CPmax obtained was 0.401.