ボリュート付新型水車の開発と性能予測

抄録

In this research, we proposed a new-type hydroturbine featuring high-efficiency and a stable internal flow in a wide range of operating conditions. To improve the turbine performance at off-designed points, it is necessary to mitigate the flow instabilities, represented by a vortex rope breakdown in a draft tube. As opposed to Francis turbine's draft tube, the new turbine is equipped with a parallel diffuser i.e. a radial vaneless diffuser and a spiral volute. The specific speed of the designed prototype is 77 [m-kW]. We carried out the CFD based investigation on the turbine. The steady simulation output a relatively broad hill-chart of the turbine efficiency than that of the same-specific speed Francis turbine. The internal flow simulated in the volute is constant because of a fresh supply from 360 degrees around the parallel diffuser outlet. It indicates that there will be low risk of vortex instability. The verification tests of the prototype turbine have been started in January 2021.