Random multistage input and energy partition approach to the description of cavitation erosion process

Abstract

Cavitation erosion process is analyzed from the point of view of energy consumption in constituent processes of the stochastic nature. Formulation of a new cavitation erosion model is presented. A kinetic approach is applied with due account taken of the random and multistage nature of the process. Mass loss is assumed proportional to the difference of the rates of the energy supply to the surface layer and the energy used for crack closure process (as well as other geometrical/environment processes contributing to retarding the cracks development). The model is thought to be the basis for prediction of cavitation erosion efficiency provided that functions and parameters used in the model are known. In view of the structure of the equations, the values of energy partition coefficients and energy input factor as well as statistical parameters are required. They are suggested to be related to the material parameters. The adequate types of probability functions of the constituent processes are also pointed out. The theoretical curves are adjusted to the experimental ones derived from the International Cavitation Erosion Test (ICET) data with calculations carried out under substantial simplifications. The general idea of the work consists in creating a simplified description of cavitation erosion, having caught the statistical dependence of the material destruction on its mechanical parameters and the loading conditions.

Stresses in the Surface Layer and Hydrogen Absorption and Diffusion in Cavitation Condition

“…These areas feature concentrations of hydrogen in the form of ions H + ( H 3 O + ) and tensile stresses. The process of adsorption and diffusion of hydrogen runs nonhomogeneously, where the main determinant is the probability of implosion of a bubble with boundary energy within a given surface microarea [23]. At the macroscopic level the deciding factor is a change in hydrogen concentration close to the crack bottom [24].…”

Selective detachment and entrainment of nanoparticles and droplets: possible cavitation erosion subprocess

“…Rough mechanical considerations in mesoscale have allowed to distinguish between the following subprocesses (components of the erosion process): 2 (i) energy transfer to the material in plastic deformations (ii) conversion of the delivered energy into microcrack surface energy (iii) energy relaxation in the process of microcrack disappearance due to their joining and absorption (iv) dumping of the microcracks generation and growth. In many cases, the enlisted processes are accompanied and amplified by corrosion processes.…”

“…Rough mechanical considerations in mesoscale have allowed to distinguish between the following subprocesses (components of the erosion process):2…”