Effect of Solid Surface Wettability on the Formation of Cavitating Wave Front with Fluid-Structure Interaction

Fluid-structure interaction (FSI) and wave propagation occurred in engineering structure may cause severe damage and result in a leakage of hazardous material from piping in a plant. However, still limited studies could be found on the propagation of cavitating wave front along with tensile wave propagation. In addition, in those studies, the cavitating wave front is assumed to exist unconditionally. The present study aims at clarifying the relation between the interfacial condition of solid-fluid interface and the dynamic cavitation generation caused by wave propagation across the solid-fluid interface with FSI. An impact experiment was conducted with a free-falling projectile which hit the cylindrical solid buffer placed on top of the water surface within the elastic tube. Cavitation bubbles were generated at the interface of the buffer and water owing to the tensile wave propagation. Then, the surface wettability of the buffer and the surface tension of water were varied to change the intensity of cavitation. In the condition with better surface wettability, the cavitation generation from the interface was suppressed. Moreover, the cavitation generation in water was not observed. Then the cavitation generation from the solid-fluid interface was evaluated with transmitted energy from solids to water. It was revealed that the more severe the cavitation intensity on the interface with worse wettability, the more energy pressure transmittance was consumed.