Abstract
The performance of variable speed radial inflow hydraulic turbines is affected by Coriolis forces. With increasing flow and rotational speed, the influence of the Coriolis force on hydraulic efficiency and performance stability becomes more significant. The performance equation for variable speed turbines is based on Newton's Law of Conservation of Energy and describes the balance between the static and the kinetic fluid energy. To define the influence of each form of energy the kinetic fluid energy is divided into translatory, rotatory and Coriolis energy. A desirable result it is that the Coriolis energy increases the hydraulic efficiency, but it is shown that Coriolis forces also cause the performance curves for constant rotational speed to cross each other, generating undesirable regional instabilities.
