Pressure pulses in Francis Turbines vs. guide vane design

In order to investigate the pressure pulses at the inlet of a Francis runner, unsteady pressure measurements are carried out in the volute region between the outlet of the guide vanes and the inlet of the runner in a model turbine. The results show that the dominant pulse in this area is the blade passing frequency. By removing the splitter blades on the runner or adding end sealing on the guide vanes, the pressure pulses was changed and gave higher pressure pulses, while smaller changes on the guide vanes or stay vanes did not affect the results.