Reversible Counter-Rotating Type Hydroelectric Unit for Tidal Power Station

摘要

To cope with the warming global environments, the authors have proposed the counter-rotating type hydroelectric unit. This unit may take place of the traditional bulb type turbines, and is suitable for not only the hydropower on the land but also the tidal power in the ocean. This paper discusses the effects of the setting angles of the front and the rear runner blades on the turbine performances, and presents the optimum setting angles at the on-cam operation, which is applicable to the gradual change of the tidal head at the large power station. The maximum output or the maximum efficiency is got at the larger unit discharge with the decrease of not only the blade number but also the blade setting angle. The on-cam hill chart gives the optimum blade setting angles to operate the unit at the specified efficiency or output. Besides, the runner blades were modified to get the fruitful output from not only the rising but also the falling tides at the power station with the dam/weir/sluice. The performances against the relative rotational speed have almost the same profiles as those of the normal runners and the maximum hydraulic efficiency is compared favorably with that of the normal runners.