Improvement of Hysteresis Characteristics of Francis Pump-Turbines When Operated as Turbine

The turbine hysteresis characteristics in Francis pump-turbines when operated as turbine were reported in the previous paper [1]. In the present report the characteristics of inner flow of runners will be observed and at the same time the effect given by the entrance angle of runner vanes and the sweepback at the entrance of runner vanes to the performance of pump-turbine will be studied. As a result, the enlargement of the sweep-back at the entrance of runner vanes is to be proved as a desirable remedy to hysteresis characteristics of Francis pump-turbines.