CFD Simulation of Defogging Effectivity in Automotive Headlamp

Abstract

In the past decade, the condensation of internal air humidity in automotive headlamps has become more prevalent than ever due to the increased usage of a new light source—LEDs. LEDs emit far less heat than previously-used halogen lamps, which makes them far more susceptible to fogging. This fogging occurs when the internal parts of the headlamp fall to a temperature below the dew point. The front glass is most vulnerable to condensation due to its direct exposure to ambient conditions. Headlamp fogging leads to a decrease in performance and the possibility of malfunctions, which has an impact not only on the functional aspect of the product’s use but also on traffic safety. There are currently several technical solutions available which can determine the effectivity of ventilation systems applied for headlamp defogging. Another approach to this problem may be to use a numerical simulation. This paper proposes a CFD (computational fluid dynamics) simulation with a slightly simplified 3D model of an actual headlamp, which allows simulation of all the phenomena closely connected with fluid flow and phase change. The results were validated by real experiments on a special fogging–defogging test rig. This paper compares three different simulations and their compliance with real experiments.

Hygroscopic Behavior of Polypropylene Nanocomposites Filled with Graphene Functionalized by Alkylated Chains

“…The internal temperature of headlamps increases via the operation of the light source, and condensation occurs because of the temperature difference with the external environment. This in turn occurs because of the moisture inside the headlamp’s components [ 15 , 16 , 17 ], thereby requiring strategies to mitigate moisture absorption of such components. The moisture resistance of polymers can be improved by mixing an inorganic lamellar filler with an aspect ratio sufficient to alter the diffusion path of water molecules [ 4 , 5 , 6 , 18 , 19 ].…”

Reducing Moisture Absorption in Polypropylene Nanocomposites for Automotive Headlamps Using Hydrophobicity-Modified Graphene/Montmorillonite

“…In the past decades, headlamps served as simple light sources; however, in recent years, their functions have diversified because of the increasing importance of vehicle appearance and higher safety demands. Accordingly, the internal geometry of the lamp is becoming more complex, and headlamp parts are increasingly prepared using polymers because of their high design freedom [1][2][3][4]. However, because of the added functions and more complex design, automotive headlamps have gradually become heavier.…”

“…Several studies have analyzed the aforementioned fogging phenomenon. For example, Guzej and Zachar [2] used computational fluid dynamics (CFD) simulations with a simplified three-dimensional (3D) model of a headlamp to simulate phenomena related to fluid flow and phase changes. Watson et al [1] described a technique for the transient numerical simulation of liquid film formation on surfaces during lighting, as well as thermal analysis, using CFD, including the effects of the properties of the liquid film on thermal solution.…”

“…As explained above, the moisture that condenses inside headlamps originates from that contained inside the plastic components such as the housing or bezel [2][3][4]. Therefore, to mitigate condensation, the reduction of the moisture absorption of these components is necessary.…”

Optimization of the automotive air conditioning system using radial basis function neural network

“…Therefore, effectively improving the defrosting performance of automobile air conditioning systems has become a serious problem in the auto industry [2][3][4]. With the development of computer techniques, the computational fluid dynamics (CFD) technique has been widely used in the optimization research of defrosting performance [5][6].…”