Particle image velocimetry measurements in the vaneless space of a model Francis turbine under steady state operation

Two-dimensional, two component particle image velocimetry (PIV) measurements of the guide-vane wake and vaneless space for a high head Francis model turbine are presented. Measurements have been carried out with a fixed head and rotational speed for a set of guidevane openings representative of part load, high load and best efficiency operating points. The measured trajectory and strength of the guide vane wake for the different operating points is discussed in conjunction with the periodic velocity oscillations. It is hoped that the present measurements will aid in further analysis as well as provide an additional set of data for validation of numerical analyses.