Surface damage caused by the interaction of particles and a spark-generated bubble near a solid wall

Abstract

Machine components operating in a fluid under conditions of cavitation and hard particle erosion can be severely affected by wear, which may reduce the lifespans of the components. To understand this synergic behaviour, in this work, experimental and numerical approximations of the damage caused by a particle interacting with a spark-generated bubble were developed. The effects of particle size, particle material, bubble position, surface material and bubble size on the damage of a surface impacted by a particle propelled by the spark-generated bubble were evaluated. The experimental results show that under the tested conditions, the heaviest particles and larger bubbles caused more considerable damage, while the initial position of the bubble did not exert a significant influence. It was found that the relationship between the increase in the bubble size and the increase in damage was quadratic. Numerical simulations involving computational fluid dynamics (CFD) and explicit finite element analysis (FEA) of a particle interacting with bubble of several sizes were conducted. The findings exhibited good correlation with the experimental data which validated the proposed numerical models. Additionally, the simulation indicated that the damage on the surface was linearly related to the kinetic energy of a particle. Furthermore, it was identified that particles closer to the bubble nucleation point had higher velocities and could thus lead to more considerable damage to the surface; however, when the pressure inside the initial bubble was high (which produced larger bubbles), the bubble interface moved faster than the particle, and the particle was trapped by the bubble, which decelerated the particle and reduced the velocity of impact on the surface. The obtained results could help to explain the mechanism of interaction between the particle and the bubble and its correlation with solid surface damage.