A Photoelastic Study of Impact Pressure by Model Microjet

Abstract

In this report, in connection with the cavitation microjet, the behavior of a model microjet is photographed by a high-speed camera. The stress fringe propagating in a photoelastic material is also photographed, when the model microjet hits the material. From this experiment, it is revealed that the jet diameter of more than 0.6mm is necessary to generate the stress fringes in the impact velocity range of 40-140m/s. On the other hand, when a water layer exists on a solid wall, the following happens ; an impulsive pressure acts on the solid wall, when a jet whose diameter is 1.3-1.7mm hits the water layer surface and the solid wall. For a jet whose diameter is 1.0-1.2mm it acts on the solid wall, when the jet hits the water layer surface in case of the water layer thickness Th≲1.5mm, and while the jet front moves through the water layer in case of the thickness Th≲1.5mm.