Flow Analysis in Francis Water Turbines

Abstract

It is the intent of this study to investigate the flow field in Francis water turbines operated at various guidevane settings with the use of analytical techniques. The flow fluid is analyzed with a streamline-curvature method and the underlying theory is discussed briefly. With the analysis, certain lower and upper limits for the guidevane settings can be defined. Within these limits only a small drop-off in efficiency at the extreme settings can be expected. Outside these limits severe cavitation and flow reversals are shown to take place. In the Appendix, it is shown how the analysis can be used to evaluate the effects of different passage and blade geometry on the flow field.