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CFD Modelling of Headlamp Condensation

Mikael Aspelin ; Johan Brunberg
Göteborg : Chalmers tekniska högskola, 2011. Diploma work - Department of Applied Mechanics, Chalmers University of Technology, Göteborg, Sweden, ISSN 1652-8557; 2011:34, 2011.
[Examensarbete på avancerad nivå]

An automotive headlamp is exposed to thermal variations together with low air exchange. The possibility of humidity entering the headlamp will therefore increase the risk for condensation to form on the lamps inner surface. The automotive industry today is highly competitive and tends to focus more on reducing costs together with consumers demanding more advanced features and styling characteristics such as transparent optical plastics and low energy emitting lamps. This will cause problems if dew is formed and visible from the outside. Physical testing and validation are not available until late in the development process and are expensive to perform. Therefore it is of great importance for the car manufacturer to be able to simulate the risk for condensation early in the design stage and thereby also reduce the cost. Thus, the goal in this thesis is to develop a numerical method with help of Computational Fluid Dynamics (CFD) that will predict if and where condensation will form in an automotive headlamp. Engineers at Saab Automobile AB today rely fully on physical testing obtained from climate tunnel experiments, pushing the headlamp to its limits during extreme weather conditions and thereby visualizing the behavior of condensation. The purpose is to evaluate if a numerical method is possible to include the condensation phenomena and compare the dew pattern formed during the climate tunnel experiments to the numerical model. Furthermore, a numerical model was successfully developed and predictions of condensation were found to be within an acceptable range, though with a slight deviation. It was also found that the possible source of deviation may lie in how scattering of light is treated in the numerical model, foremost the boundary conditions governed by it. Hence, further work is imposed to solve this.

Nyckelord: Headlamp, Condensation, CFD



Publikationen registrerades 2011-11-21. Den ändrades senast 2013-04-04

CPL ID: 148760

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