The main task of the automotive headlights on cars is to illuminate the roadway and facilitate the driver fatigue-free and safe driving. An automotive headlamp is exposed to thermal variations during its operations and also exposed to the different environmental conditions. Automotive headlamp compartment is not completely sealed and vents are provided to exchange the air between environment and headlamp compartment for thermal cooling of the internal components.
An automotive headlamp compartment is an environment with high thermal and low air flow exchanges with the ambient as results humidity can accumulated inside the headlamp compartment and there is a possibility of thin mist layer formation on the lens inner surface [1]. The combined use of numerical simulation and experimental studies is an important approach for headlamp design.
This paper summarizes CFD simulation results for automotive headlamp condensation and de-condensation using ANSYS FLUENT. In this study, transient multiphase fluid flow with natural convection, conduction and radiation heat transfer were performed along with species transport. Radiation heat transfer is modelled using “Discrete Ordinate” (DO) model [2] which takes into account of heat transfer through semi-transparent media. Multiphase flow is modelled using Eulerian wall film approach which models condensation and de-condensation of water vapor. The variable diffusivity of the water vapor inside the headlamp compartment is defined using user defined function in ANSYS FLUENT. Both CFD and experimental results are presented in this paper, which shows good agreement, demonstrating enormous potential of proposed CFD based approach for reduced product development and cost.