Investigating high-speed liquid impingement with full-field measurements

Abstract

Repeated high-speed liquid impingement on solid surfaces results in erosion that can have undesirable consequences. In recent years, the capacity of model predictions has exceeded the experimental measurements of an impingement; this work closes the gap. Using the grid method, tens of thousands of individual measurements of surface displacement were taken of the response of a polymethylmethacrylate test specimen to the impingement of a high-speed ( 233   m   s − 1 ) curved-fronted water jet. The full-field measurements were taken at a rate of 5 MHz and interpreted using two models based on differing sets of assumptions. The results support the current qualitative description of a high-speed impingement. However, the widespread assumption of a rigid solid surface in existing analysis and modelling was found to be inaccurate: only the model that recognized the effect of the compliance of the solid surface was successful in predicting the measured temporal and spatial variation in displacement and acceleration. This model predicted that the energy absorbed by the solid surface was less than 0.3% of the total kinetic energy of the equivalent droplet impingement.