抄録
A ducted Darrieus-type turbine has been proposed for extra-low head hydropower utilization of total head less than 2m. Though the hydro turbine system, in general, might consist of an intake, runner section and the draft tube for higher efficiency operation, it was clarified in previous experiment that there was no need of the side-walls of runner section and a draft-tube for keeping the performance high, in the case of duct with an inlet nozzle, which yields a simplification of the structure of the turbine system. In order to reconfirm this result for large-sized turbine with 500×300mm duct, instead of small-sized one with 400×200mm, the side-wall effect on turbine performance was experimentally investigated for three- or four-bladed runner. In the present paper, the experimental results are shown with considering flow behaviors in the runner section.
