LES study of the precessing vortex core mitigation by radial injection in a Francis turbine air model

This work is devoted to a numerical study of the precessing vortex core (PVC) mitigation in a Francis turbine air model. The approach utilized to suppress the PVC, injection of radial jets, was based on influencing flow zones that are most susceptible to control. The analysis of the time-averaged velocity fields revealed extending of a recirculation zone. The time-averaged pressure pulsations in the flow decreased significantly, that indicates a mitigation of the PVC dynamics. Spectra of the azimuthally decomposed pressure pulsations signal demonstrated a suppression of the m = 1 mode by 25% and m = 2 by 40%, however, it does not coincide with the control efficiency in experimental work of I. Litvinov et al. In further investigations it is planned to vary the spatial orientation of the injection jets in order to achieve more effective PVC suppression.