Exploiting Air-bubble Reflection for Reducing Propeller Caviation Induced Hull Excitation

Single nozzle arrangement in the full-scale ship reveals that a significant reduction of propeller cavitation induced pressure amplitude is possible at the outside of air-bubble layer, where the isolation effect of the air is not involved. Resulting hull-vibration reduction is approximately 75 %. Instead of excessive consumption of air, that is, considerably small amount is necessary for a reduction of propeller excitation, which can make the constitution of relevant system simple. Hence the purpose of this study is to provide a physical proof for such a beneficial phenomenon. By approximating the solution of acoustic reflection from a bubble, we could find that phase-reversal reflection provoking a destructive interference is the main reasoning for a pressure reduction outside the layer.