Local structure of a water jet and the related damage mechanism of a metallic material.

Abstract

This paper is concerned with an experimental verification of the correlation between the local structure of a high-speed water jet in air and the damage process in a metallic material resulting from the impingement of the water jet. The experiment was made under the conditions of 30 MPa to 90 MPa in injection pressure and a nozzle inner diameter of 1 mm. The metallic material tested was aluminum. Three kinds of liquid (tap water, polymer solution and ion-exchanged water) were used as working fluids. Stroboscopic observations of the structure of the liquid jet and erosion tests were carried out for various liquid temperatures. The following facts were clarified : The mass loss increases remarkably with the addition of the polymer. The effect of the polymer additive on the structure of the water jet is to reduce the number of small-scale droplets, while leaving large-scale motions unchanged. Increasing the liquid temperature causes an increase in the mass loss.