Development of a hybrid Lagrange–Euler transition model for the film formation and dynamics of an impinging liquid spray

Abstract

This paper proposes a hybrid Lagrange–Euler transition model that fully describes the injection and film formation process with different transition sub-models to balance accuracy and efficiency under the incompressible framework for spray cooling of electric machines. When the liquid phase is far away from a wall or film, a Lagrange discrete particle modeling method is employed to track liquid phase motion, which then transforms into a Eulerian droplet when a particle is close to a wall or film. Thereafter, the volume-of-fluid (VOF) method is adopted to simulate the processes of impingement, wall film formation, and dynamics. The transition model is implemented with the CONVERGE code package and validated against several available experimental data ranging from single droplets to spray impingement. The results indicate that the hybrid Lagrange–Euler transition model exhibits excellent mass and momentum conservation under different mesh resolution conditions and can well reproduce film formation and dynamics behaviors. In addition, detailed comparisons between the transition model and particle-based thin film modeling (TFM) are made for wall film formed by spray impingement. The transition model predicts a smaller film area and a better film shape than the TFM model compared to the measurements. Overall, the transition model coupled with the VOF method shows a higher sensitivity to mesh resolution, whereas the TFM model is more easily affected by semi-empirical splash models.