On-cam operation of counter-rotating type hydroelectric unit

To cope with the warming global environments, the authors had proposed the counter-rotating type hydroelectric unit, which is composed of the tandem runners and the peculiar generator with double rotational armatures. This unit can be supplied to various water circumstances, for instance, the traditional large hydropower, the mini/micro hydropower, and the tidal power. The fundamental performances and the flow conditions around the runners have been investigated and the design materials for the runners have been presented. Continuously, this paper discusses the performances at the on-cam operation, in the large tidal power station. The model unit was operated while keeping the relative rotational speed constant nT = 900 min−1, namely 60 Hz, irrespective of the hydropower circumstances. The output and the hydraulic efficiency are affected by the blade setting angles of the front and the rear runners. Resultantly, both optimum angles giving the maximum output and/or the maximum efficiency are presented at the various discharges/heads.