Effect of Hub Configuration on the Performance of Mixed Flow Turbine for Micro Hydropower in Pipes

As environmental issues have been on the rise recently, the demand for hydropower is increasing. Micro hydropower in pipes is highly safe, sustainable, and easy to introduce. In this study, a mixed flow turbine is introduced to collect waste energy in pipes, and numerical analysis was conducted to estimate the performance. Efficiency was adopted as an indicator to evaluate the performance, and the performance of three different hub configurations, which are conical, convex, and concave, was investigated. The hydroturbine used in this study was modeled except for the guide vane due to the small scale, and the blade was designed using design of experiments. As a result, three different hub configurations have the best efficiency point between rotational speeds of 3000 rpm and 3200 rpm. The convex hub showed the highest efficiency, which was 1.60% and 3.63% higher than the conical and concave hub, respectively. It is related to the variation in the cross-sectional area of the flow path of the runner depending on the hub configuration. Consequently, the convex hub configuration showed the best performance.