An Experimental Study of the Model Microjet

Abstract

In this experiment, in connection with the cavitation microjet, the behavior of a model microjet, produced by a water capsule, is photographed by a high-speed camera and its impact pressure is measured by a piezo-type pressure transducer. When the model microjet, whose diameter is 1.3 to 1.7 mm and impact velocity is 85 to 115 m/s, impacts directly against the solid wall, an impact pressure of 10 to 15 MPa is measured. The impact pressure, however, decreases very much, when a water layer exists on the solid wall and its thickness is greater than 1.5 mm. The measured time of the maximum impact pressure, detected on the solid wall, coinsides with our previous experimental results, obtained by the photoelastic method. Moreover it is shown that most of the test pieces of pure aluminum are damaged by the model microjet, whose diameter is 1.3 to 1.7 mm and velocity is 85 to 120 m/s, and that the damage pattern is clearly influenced by the shape of the microjet front.