DISCUSSION ON OSCILLATION PERIOD OF LASER-INDUCED SINGLE BUBBLE NEAR RIGID WALL IN LIQUID NITROGEN AND DISTILLED WATER

摘要

This paper describes an investigation of behavior of laser-induced single bubble in pressurized liquid nitrogen and distilled water. In addition, we performed experiments on oscillation period of bubble motion in pressurized liquid nitrogen, and compared it with that in distilled water at room temperature. Single bubble is produced by focusing of pulsed laser beam into liquid nitrogen and the motion of the bubble is visualized by shadowgraph technique with high speed camera. In order to increase the degree of subcooling, nitrogen gas pressure is applied to liquid nitrogen. The degree of subcooling is significant parameter for behavior of bubble in weakly subcooled liquid nitrogen. Generally, thermo-physical properties as low latent heat, surface tension, and viscosity of cryogenic liquid are different from those of water at room temperature. For this reason, collapse of cavitation bubble in cryogenic liquid may be affected by thermo-physical properties. We have discussed influence of thermal parameter as degree of subcooling on the oscillation period of single bubble in cryogenic liquid. It is found that the behavior and oscillation period of single bubble near rigid wall in liquid nitrogen differ from those of water between low and high subcooled region.