Influence of the velocity field at the inlet of a Francis turbine draft tube on performance over an operating range

Abstract

We evaluate the sensitivity of the draft tube losses to the velocity field entering a given Francis turbine draft tube while this turbine is operated within a range of discharge values including part-load and full-load regimes. Within the present methodology, the velocity field at the draft tube inlet is determined prior knowing the runner by solving a variational problem for the kinematically constrained swirling flow. © 2013 Published under licence by IOP Publishing Ltd.