抄録
An undershot cross-flow water turbine does not require a casing for open channels and hence considerable simplification is attained. However, because this water turbine does not have a casing and has a free surface, it is believed that the flow field considerably changes with the number of blades. In this study, the effects of number of blades on performance and flow field of undershot cross-flow water turbine at a constant flow rate are investigated by an experiment and numerical analysis, and the following facts are clarified. The torque and power of the runner with 8 blades are lower than them of the runner with 24 blades. Furthermore, torque fluctuation of the runner with 8 blades is larger than it of the runner with 24 blades. It is because the runner with 8 blades has little underwater number of blades.
