Pressors Fluctuations and Fatigue Stresses in Storage Pumps and

Similarity is shown between a model and a f ull scale pump or pump-turbine in the static and dynamic fields of stress and in the vibration characteristics, if the peripheral speed of rotation and the material used for the blades are the same for the two machines. Simple formulas are derived for predicting phase coincidence of the pressure fluctuations caused by the blade passage of the runner rotating in a diffuser. Test results are shown which confirm the established theory. This work was made as part of a joint develop-ment work on pump-turbine by Suizer Brothers, Ltd., and English Electric Company. WHEN developing modern storage pumps or reversible pump-turbines, the designer has to face two classes of problems. The first is related to the h3'draulic characteristics of the machine when pumping, and when operating as a turbine. These problems can be solved by using model machines working under low head conditions. The head-flow characteristics, the efficiency curves, and the data relating to cavitation can be measured with a high degree of accuracy. The scale up in pressure and size t