Impact of self-excited cavitating waterjet feeder pipe on acoustic and erosion patterns

The impact of the feeder pipe geometry on the dominant frequencies and erosion patterns induced by self-excited cavitating waterjets, SECJ, is studied using laboratory experiments. Complementary inspection of the bulk flow in the feeder sections is illustrated using averaged governing equations. The experimental results indicate that the feeder pipe length, L2, affects the acoustic characteristics of the waterjets. As an acoustic reflector, the length of feeder pipes induces distinct transmission losses, resulting in resonant intensity changes and reflectivity. The relatively larger section of the feeder section with respect to the upstream fitting led to the formation of a large-scale recirculation pattern due to a sharp shear layer from the incoming flow. This recirculation bubble may cover the entire or a fraction of the feeder extent depending on L2. Overall, the work offers insight into the design of required pipe system parameters to modulate peak resonance.