Experimental and Analytical Study of under Water Pressure Wave Induced by the Implosion of a Bubble Generated by Focused Laser.

Abstract

In various domains of material processing, such as surface cleaning and surface treatment, cavitation phenomenon may become an alternative to traditional methods if this phenomenon is well understood. Due to experimental and mathematical difficulties in theoretical models, it is still a challenge to accurately measure the physical mechanism of the fluid/structure interactions. In this study, we verified the feasibility of using polyvinylidene fluoride (PVDF) sensors to quantitatively measure the under-water pressure wave generated by the collapse of a single cavitation bubble. The electrical signal obtained by PVDF can be converted into pressure information only by using the sensor material parameters provided by the supplier. During the conversion process, only the capacitance of the acquisition chain needs to be additionally measured. At the same time, a high-speed video recording system was used to visualize the evolution of the cavitation bubble. The Gilmore analytical model and an associated wave propagation model were used to simulate the pressure peak of the first collapse of the cavitation bubble. This theoretical pressure was compared with the experimental results. The result showed that, for bubbles with a normalized standoff distance larger than 5, the PVDF sensor had the ability to quantitatively measure the pressure wave generated by a single cavitation bubble.