Synergy between cavitation and solid particle erosion in an ultrasonic tribometer

Abstract

Two of the most common wear phenomena in hydraulic machinery are cavitation damage and solid particle erosion. Depending on conditions, such as particle concentration, size and cavitation intensity, a synergy effect that increases wear can occur. This study evaluates the wear of the AISI 316 stainless steel simultaneously exposed to particle erosion and cavitation erosion. An assembly is made with an ultrasonic cavitation tribometer modified to include sand particles and distilled water. The experimental design is carried out for two particle sizes and three different concentrations of sediment, representative of the conditions of hydraulic turbines exposed to wear in industry environment. Measurements of accumulated wear are made over a 6-h test period, and the surface wear is analysed by means of optical stereoscopy and scanning electron microscopy. The results show that for the largest particle size analysed, the wear increases proportionally with the concentration; however, for low concentrations and the smallest size, the damage was inhibited, which shows a mutual dependence between the concentration and particle size in the inhibition or acceleration of cavitation damage.