Numerical simulation of droplet impact onto heated surfaces below the boiling point

Abstract

Abstract Droplet impact onto heated surfaces is a widespread process in industrial applications, particularly in the context of spray cooling techniques. Therefore, it is essential to study the complex phenomenon of droplet spreading, heat removal and flow distributions during this process. The primary focus of this research centers on the wetting dynamics at a surface temperature below the saturation temperature of the liquid. This study employs a Computational fluid dynamics (CFD) framework to simulate the impact dynamics of a water droplet onto a heated surface. The impact dynamics, spreading, air entrapment and heat transfer in the process are discussed using simulation results. The Direct Numerical Simulation (DNS) tool Free Surface 3D (FS3D), an in-house code at the Institute of Aerospace Thermodynamics, University of Stuttgart, is utilized. The Finite-Volume method is used to solve the incompressible Navier-Stokes equations, and the interface is defined by the Volume of fluid (VOF) method. In this study, the temperature change above the entrapped air bubble formed due to droplet inertia is shown, which can influence the heat removal rate in the process. Therefore, conducting a comprehensive study on the temperature shift caused by the air bubble is crucial.