Date of Graduation
Statler College of Engineering and Mineral Resources
Mechanical and Aerospace Engineering
Gary J. Morris
Robert E. Bond
Thin filaments for use in glass, polymer, or textile industries are formed by extruding molten material through an orifice to form a continuous filament. These filaments are cooled rapidly from the melting temperature of the material to near room temperature. If this cooling occurs too rapidly or too slowly imperfections can develop in the filaments. These imperfections can decrease the overall quality and strength of the fiber sometimes leading to temporary production shutdowns caused by filament breakage.;Driven by the need to understand and control the cooling of thin filaments, research has been conducted to attempt to experimentally characterize the heat transfer experienced by a thin filament. For this study, a platinum filament was placed axially in a vertical wind tunnel and electrically heated. Forced convective air flowing over the stationary heated filament was used to simulate the heat transfer associated with a forming filament moving through still air. A computerized data acquisition system was utilized to collect information on the heat dissipated by the filament. These data in addition to freestream data were used to evaluate the heat transfer coefficient. Data were collected for 5 different filament diameters, 25.4, 38.5, 51, 63.5 and 76 microns for 5 different dynamic pressure settings, 0.0, 0.466, 0.931, 1.397, and 1.863 mm Hg over a temperature range of 400 K to 1100 K in increments of 100 K. These data were taken at a zero crossflow setting. The angle of the test filament with the freestream was altered producing a crossflow effect and the same data were recorded for 2.5°, 5° and 7° crossflow angles. From these data an empirical equation was developed for the heat transfer coefficient as a function of filament diameter, temperature difference between the filament and the freestream, freestream velocity and crossflow angle. When compared with the experimental data the empirical equation was accurate to approximately 11.5%.
Cragg, Amy J., "Experimental characterization of heat transfer from an electrically heated thin filament" (1999). Graduate Theses, Dissertations, and Problem Reports. 1888.