Numerical Study of High Speed Liquid Droplet Impingement Phenomena by Fluid/Material Coupled Numerical Method

Abstract

Serious damages are possibly caused by high-speed Liquid Droplet Impingement (LDI) on the material surface. In particular, the wear by LDI in piping system of nuclear power plant is becoming great problem in recent years because of high aging operation. Therefore, it is important for the safety of piping systems in nuclear power plant to evaluate accurately effect of high speed LDI on the inner pipe wall. In this study, by using our in-house fluid/material two-way coupled numerical method which considers reflection and transmission on the fluid/material interface, high-speed LDI on material surface is simulated. The algorithm of two-way coupled method at fluid/material interface is applied as follows: fluid pressure on material surface and normal stress of vertical direction of material surface are obtained by considering reflection and transmission of pressure and stress waves based on acoustic impedance. Nonslip condition is adopted on fluid/material surface, where the vertical velocity has the values obtained by considering reflection and transmission and the tangential velocity of fluid has the same velocity of material which is calculated by material analysis. From the numerical results, it is shown that variation of impingement velocity has an effect of linear for maximum pressure and equivalent stress but variation of droplet diameter has little an effect of these values.