Prediction of Scalable Loss in Francis Runners of Different Specific Speed

Abstract

Hydraulic losses are composed of scalable loss and non-scalable loss. For the determination of scale-up formulae in hydraulic turbines, it is important to predict the scalable loss, that is the friction losses in a runner and fixed channels, as precisely as possible. However, it is still difficult to determine them both theoretically and experimentally, partly because the boundary layer is too thin to prepare sufficient mesh size for CFD, and partly because the scalable loss cannot be separated experimentally from the measured total hydraulic loss.