Dynamics of vortex cavitation involved in the erosion of hydraulic machines

In order to investigate the dynamics of the vortex cavitation, which is found to be responsible of the cavitation erosion in hydraulic machinery, a cavitation vortex generator (CVG) is used. By producing the cyclic growth and collapse of cavitation vortex, this device provides a good simulation of the realistic hydrodynamics situation corresponding to the travelling cavities downstream a fixed leading-edge cavity. The simultaneous use of the shock and the pressure time-history recordings and the high speed Cranz-Schardin visualizations allows us to describe the instantaneous cavity motion in the CVG test section . The most important result is the evidence of a strong spherica1 shock waves emission at the time of the cavitation vortex collapse, leading to overpressure of more than 10 kbar.