Turbomachinery

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The aim of this study is to develop an ultralow-head water turbine for an open channel, such as an irrigation channel, in order to effectively use hitherto unused hydropower energies. By focusing on a cross-flow runner, we eliminated the casing and used the application as a water turbine(undershot-type cross-flow water turbine)for an open channel. We investigated the performance and internal flow of the water turbine at a constant flow rate through an experiment and computational fluid dynamics(CFD)analysis. As a result, the following facts became clear. The performance and internal flow of the proposed water turbine with a free surface can be predicted to a certain extent by CFD analysis. At the best-efficiency-point rotational speed, θ=21-91° is the first-stage inlet area and θ=91-132° is the second-stage outlet area on the outer circumference of a runner. Moreover, on the inner circumference of the impeller, θ=48-109° is the first-stage outlet area and θ=109-141° is the second-stage inlet area.

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