Numerical modeling and analysis of glass fiber drawing process from large sized silica preform

Abstract

As fiberoptics industries have been attempting to use a silica preform of larger diameter in order to reduce facility down time and increase optical fiber manufacturing productivity, this computational study investigates how the use of large sized preform in sized up draw furnace affects high speed glass fiber drawing process. Present computational model for glass fiber drawing simulations employs iterative scheme between one-dimensional momentum balance model for neck-down profile of heated and softened preform and two-dimensional axisymmetric thermo-fluid computations of convective and radiative heat transport for preform heating and purge gas flow inside muffle tube. Prediction of preform neck-down shape for 10 cm diameter preform has been verified with measured profile from actual optical fiber drawing test. The effects of larger preform diameter up to 20 cm are appreciated and discussed on temperature distribution of preform and drawn glass fiber and fiber draw tension. This study also shows that fine control of heating condition is necessary to maintain proper amount of draw tension in high precision glass fiber drawing.