A PREDICTIVE MODEL FOR LOCALIZED EROSION CORROSION

A predictive numerical model for localized erosion-corrosion of metals in disturbed two-phase flow has been developed. The flow structure is determined by the application of a two-phase flow version of a k - epsilon eddy viscosity, low Reynolds number model of turbulence. The Eulerian approach for the fluid flow is coupled with a Lagrangian approach for particle motion. Local values of fluid velocity and turbulent and molecular transport coefficients are determined along with particle-wall interactions in terms of impact velocity, angle, and frequency. The corrosion component of the model assumes mass-transfer control. The mass-transfer rates are determined by the solution of the mass-transport equation simultaneously with the fluid flow equations. The erosion is determined on the basis of the computed particle-wall interactions and cutting-wear erosion equations. Simulation results for the erosion of stainless steel and the erosion-corrosion of mild steel at a sudden expansion in a vertical pipe carrying a dilute 2% sand/water slurry are compared with previously measured values. The erosion-corrosion rates at a groove in a steel pipe are also presented to demonstrate the generality of the model.