An Investigation of the Viscous Flow Problem Associated with the Heating of the Glass Preform During Optical Fiber Processing

Abstract

ABSTRACTA thermal study of the optical fiber manufacturing process involves some of the most challenging, and in some cases, unsolved fundamental problems in heat transfer and fluid Mechanics. The heating stage of the process, where the glass cylinder (preform) is heated radiantly by the cylindrical muffle furnace, greatly influences the resultant quality of the fiber. During the process a neckdown region is formed that is characterized by the stretching of the glass. The two-dimensional transient equations of motion and Mass conservation, with viscosity dependent on temperature, were solved to obtain the velocity profiles in the glass and the shape of the neckdown region. Axial velocity contours and the neckdown profiles were examined for various drawing conditions. Differences between the new method presented here and existing one-dimensional method were examined. The analysis can be used for drawing of other materials such as metals and polymers, and the modeling is applicable to other viscous liquids.