Rubber Popper Slams and Nucleates a Toroidal Cavitation Bubble

Cavitation bubbles occur everywhere, not only in the fluid machinery but also in animal activities. In this present study, we employ the rubber popper to study cavitation upon object impact. The rubber popper can achieve fast deformation (up to 8 m/s in our case) even underwater, as it impacts a glass substrate. Three high-speed cameras allow us to visualize the dynamics of the bubble and the 3D- deformation characteristics of poppers simultaneously. We observed that cavitation occurs on the popper surface before it hits the glass substrate, forming an annular shape of the popper, and rebound multiple times. We measured the lifetime of the bubble as well as found the radius of the cavitation bubble at its peak. The impacting speed of the popper and its shape change are identified. Experimental parameters are the popper size, location, and fluid types. It was found that the higher the popper location, the larger the velocity for both popper sizes, where the small popper had an overall larger velocity at similar heights to the medium popper. Cavitation bubble lifetime was positively correlated with the bubble radius. We also discuss the possible future work and applications such as the surface cleaning process.