Water Tunnel Experiment of an Undershot Water Turbine and Performance Analysis Based on Momentum of Blade Element

Abstract

In order to recover hydraulic energy such a discharge channel of small hydropower plant, the performances of an undershot water turbines were experimented by a water tunnel. The width of the channel was much wider than the blade width and the impeller was installed sufficiently apart from the bottom surface of the channel. One of the criteria for the high efficiency turbine was to set the solidity to approximately 0.4. This result could explain that increasing the number of blades and chord length could not necessarily contribute the improvement of the performance. The momentum analysis of the blade element proposed in this study could represent the output of the water turbine with the solidity 0.4 in the vicinity of the design point.