ガイド壁とキャビティを有するクロスフロー水車の吸出管形状について

抄録

Cross-flow turbines are utilized in many run-off river types and small hydropower stations because of their excellent partial load characteristics and low manufacturing cost. But the maximum turbine efficiency is not high, so there have been many studies to improve the performance. The authors have been developing a new shape cross-flow turbine with a cylindrical cavity and a guide wall to enhance the performance by controlling the runner outflow and making the turbine small. The outflow situation will depend on the shape of a draft tube. This study focused on the influence of the wall shape in a part of a draft tube on the turbine performance experimentally. Results under various guide vane openings show that the efficiency is degraded for overload and improved for the partial load without draft tube throat. Also, the flow separation, captured with PIV measurement, from the outer casing tip changes with the change of the draft tube shape.