This content is not included in
your SAE MOBILUS subscription, or you are not logged in.
Predicting the Thermal Performance of an Automotive Fog Lamp Reflector
Annotation ability available
Sector:
Language:
English
Abstract
The thermal performance of an automotive fog lamp reflector is predicted with a computational fluid dynamics program. The 2D, steady-state heat transfer model accounts for convection and radiation within the enclosure, conduction through the reflector walls, external convection and radiation losses, and transmission through the lens. A good comparison of the predicted reflector temperatures with experimental thermocouple and infrared data suggests that the specular component of the inner metal coating plays a secondary role in the overall heat transfer and that a detailed thermal model of the bulb is not required. The radiant exchange with the tungsten filament and the conductive energy losses through the bulb connections are accounted for by specifying an appropriate heat flux at the bulb surface, and the transmission of radiant energy through the lens is modeled with an appropriate heat sink. Driven by the thermal expansion of the air near the bulb surface, 4 counter-rotating recirculation zones are predicted within the reflector enclosure. The highest temperatures are predicted at the intersection of these zones on the inner surface of the shelf above the bulb. The thermal model can be used to assess the importance of different heat-transfer mechanisms. For example, sensitivity studies show that thermal radiation within the reflector enclosure redistributes the energy so that the wall temperatures are more uniform. In addition, thermal radiation losses to the environment surrounding the reflector need to be included in the thermal model; otherwise, the predicted wall temperatures are higher than the experimental data.
Recommended Content
Technical Paper | Numerical Investigation of Natural Convection in a Simplified Engine Bay |
Technical Paper | CFD-Analysis and Experimental Verification of an Automotive Fog Lamp |
Technical Paper | Dual Fan Alternator Design Analysis |
Authors
Citation
Liang, E., Lillquist, R., Gallo, J., Poslinski, A. et al., "Predicting the Thermal Performance of an Automotive Fog Lamp Reflector," SAE Technical Paper 970912, 1997, https://doi.org/10.4271/970912.Also In
References
- Siegel, R. Howell, J.R. Thermal Radiation Heat Transfer 3rd Hemisphere, London 1992
- “Optical Properties,” Encyclopedia of Polymer Science and Engineering V 10 John-Wiley & Sons 1987
- Fused Quartz Properties and Usage Guide General Electric Company 1995
- Sherman, K.C. “Infrared Transparent Reflector Materials,” SAE Technical Paper Series 950556 : Advances in Automotive Plastic Components and Technology (SP-1099) International Congress and Exposition Detroit, Michigan 1995
- FIDAP Theory Manual Fluid Dynamics International, Inc. Evanston, IL 1993
- GE Plastics Engineering Design Database and Design Guide GE Plastics Pittsfield, MA 1989
- Chapman, A. J. Heat Transfer 4th Macmillan, New York 1984
- Schlichting, H. Boundary Layer Theory 4th McGraw-Hill New York 1960