Heat transfer of symmetric impacts of two droplets on a hot liquid film

Abstract

To gain a better awareness on heat transferring mechanism of droplet impingement on liquid films, this study adopted the coupled level set–volume of fluid method for numerically simulating the symmetric impacts of two droplets upon the liquid film. Based on the flow mechanism of multiple droplets impacting liquid film, we studied heat transferring processes of two cold droplets obliquely impacting a hot liquid film. By analyzing diverse impacting modes, droplet impacting interface morphology, splash temperature, and variations of wall heat transfer coefficient were examined, and influences of droplet spacing and film thickness on heat transfer features were examined. we found that the vertical impact upon liquid film had the best heat transferring efficiency to the wall, and the maximum wall–average heat transfer coefficient can reach 9903 W/m²·K. The symmetric outward impact upon liquid film had maximal heat transferring range. The lower liquid film thickness produced a higher local heat transfer coefficient on wall surface. Droplet spacing mainly affected the scope of variations of heat transfer coefficient but had a small influence on splash temperature.