Investigation of the diagonal-flow turbines of the Zeya hydroelectric station under low heads

Abstract

1. The optimal combiner relationships of the diagonal-flow turbines in the Zeya hydrostation differ considerably from those calculated. Realization of the optimal combiner relationship for a turbine head of 46 m makes it possible to increase the efficiency of the unit by about 8% at loads close to the maximum for this head. 2. The maximum capacity of the unit under low heads is limited by the limiting opening of the guide apparatus with a considerable margin with respect to the runner-blade angle. 3. At heads close to the start-up head the maximum output of the turbine is slightly below the output on the line of limitation of the factory operating characteristic. 4. The operation of the turbine in nonoptimal regimes is accompanied by a considerable increase of pressure fluctuations under the runner and vertical vibrations of the supporting elements of the unit. Therefore a careful adjustment of the optimal combiner relationship is necessary. 5. The maximum output of the turbine at heads greater than 50 m exceeds the value on its line of limitation on the factory operating characteristic. 6. The diagonal-flow turbines made a good showing with respect to vibrations during operation at reduced heads; there is no need to introduce operating regime limitations. 7. The diagonal-flow turbines of the Zeya hydrostation have good cavitation properties, thanks to which there is little need to protect them from cavitation.