A study on impulsive pressure of a cavitation bubble. At the 2nd collapse-reexpansion stage.

Abstract

The impulsive pressure is detected by the local pressure sensor, used in the previous report, at the 2nd collapse-reexpansion stage of a spark-induced cavitation bubble near a solid boundary. At the same time a flash photograph of the cavitation bubble is taken, and it is revealed that a microjet might be generated at the 2nd collapse-reexpansion stage of the cavitation bubble and the impulsive pressure of the microjet is about 1-2MPa, when the cavitation bubble is generated at 7-8 mm from the solid boundary. It is also revealed that the time lag between the microjet impact to the solid boundary and the shock wave generation is about 40-60 μs.