Investigation of the cavitational stability of an aluminum piston surface based on a three-dimensional model

Abstract

The problem of determining the optimal material for manufacturing the surface of a movable element (piston) is considered, which has an increased resistance to cavitation failure, in order to justify the expediency of using structural materials for the manufacture of pistons in fuel automatics elements. On the basis of three-dimensional numerical modeling of the elasticity equations, the conditions under which a cavitation bubble collapse on the surface of a piston made of various structural materials can lead to irreversible deformations of the piston. The pressure acting on the piston determined from the model of nonspherical bubble collapse with the formation of a cumulative stream. The impact on the surface of the collapse of both a single bubble and a pair of bubbles located at different distances from each other is studied. Calculations showed that with special treatment the surface of the piston will become more resistant to erosion destruction. Deformations are localized near the region to which the force is applied, at a distance of the order of two bubble diameters. Cavitation destruction of the material is associated with the yield threshold and grain size, is independent of the Young's modulus and inversely proportional to the Poisson's ratio. The simultaneous collapse of two bubbles at a distance of the order of one or two sizes of the bubble increases the maximum pressure on the surface and, consequently, increases the probability of irreversible deformation of the surface.