SPRAY IMPINGEMENT FILM ANALYSIS: CHARACTERISTICS EVALUATION AND CORRESPONDING SIMULATION METHOD

Abstract

Spray impingement is a process during which discrete spray droplets contact a solid surface and form a continuous liquid film. To thoroughly understand such a process is challenging due to the complex gas-liquid-solid interaction and coupling. The liquid converts from a continuous phase into discrete droplets, and finally back to the continuous phase again on the plate. On the basis of experimental analysis, this work investigates a computational fluid dynamics model in the Lagrangian-Eulerian system to focus more on the film dynamics during the impingement. The impingement criterion is modified to incorporate a more accurate momentum transfer within the liquid film. Furthermore, a submodel of droplet slide is coupled into the numerical model to analyze the effect where droplets with a high horizontal velocity will glide away from the plate without contacting it. The numerical model is validated by free spray experiments in the aspects of spray morphology, droplet size, and droplet velocity. Afterward, film dynamics are validated from experimental film thickness measurement with the high-speed laser-induced fluorescence technique. The results show that the modified Bai-Gosman model in the Lagrangian-Eulerian framework can well predict the motion and characteristics of the impingement film, and incorporating the glide model further improves the approximation in many aspects.