Transport Processes Governing the Drawing of a Hollow Optical Fiber

2008 ◽  
Author(s):  
Jing Yang ◽  
Yogesh Jaluria
Keyword(s):  
Optical Fiber ◽  
Transport Processes ◽  
Solid Core ◽  
Drawing Process ◽  
Variable Properties ◽  
Zonal Method ◽  
Drawing Speed ◽  
Optical Fiber Drawing ◽  
Feeding Speed ◽  
Core Fiber

This paper presents a mathematical model to simulate the silica hollow optical fiber drawing process. Two neck-down profiles, which represent the inner and outer surfaces of the hollow fiber, are generated by using an iterative numerical scheme. The zonal method is applied to calculate the radiative transport within the glass. The effects of variable properties for air and buoyancy are investigated and results indicate that these can be neglected for simulating the draw process. The validation of the model is carried out by comparing the results with those obtained by using the optical thick method as well as those for a solid-core fiber. The effect of drawing parameters like the temperature of the furnace, feeding speed and drawing speed on the temperature and velocity distributions and on the draw tension are studied. It is found that the geometry and qualities of the final hollow optical fiber are highly dependent on the drawing parameters, especially the drawing temperature and the feeding speed.

Transport Processes Governing the Drawing of a Hollow Optical Fiber

2009 ◽  
Vol 131 (7) ◽  
Author(s):  
Jing Yang ◽  
Yogesh Jaluria
Keyword(s):  
Optical Fiber ◽  
Transport Processes ◽  
Solid Core ◽  
Drawing Process ◽  
Variable Properties ◽  
Zonal Method ◽  
Drawing Speed ◽  
Optical Fiber Drawing ◽  
Feeding Speed ◽  
Core Fiber

This paper presents a mathematical model to simulate the silica hollow optical fiber-drawing process. Two neck-down profiles, which represent the inner and outer surfaces of the hollow fiber, are generated by using an iterative numerical scheme. The zonal method is applied to calculate the radiative transport within the glass. The effects of variable properties for air are investigated and results indicate that these can be neglected for simulating the draw process under typical draw conditions. Inclusion of buoyancy in the flow is also studied and it is found that the flow can be significantly affected due to buoyancy. The validation of the model is carried out by comparing the results with those obtained by using the optical thick method as well as those for a solid-core fiber. The effects of drawing parameters such as the temperature of the furnace, feeding speed, and drawing speed on the temperature and velocity distributions and on the draw tension are studied. It is found that the geometry and qualities of the final hollow optical fiber are highly dependent on the drawing parameters, especially the drawing temperature and the feeding speed.

Thermal Transport and Flow in High-Speed Optical Fiber Drawing

1998 ◽  
Vol 120 (4) ◽  
pp. 916-930 ◽  
Author(s):  
Zhilong Yin ◽  
Y. Jaluria
Keyword(s):  
Optical Fiber ◽  
Thermal Transport ◽  
High Speed ◽  
Radiative Transport ◽  
Gas Velocity ◽  
Furnace Temperature ◽  
Fiber Drawing ◽  
Zonal Method ◽  
Optical Fiber Drawing ◽  
Purge Gas

The thermal transport associated with optical fiber drawing at relatively high drawing speeds, ranging up to around 15 m/s, has been numerically investigated. A conjugate problem involving the glass and the purge gas regions is solved. The transport in the preform/fiber is coupled, through the boundary conditions, with that in the purge gas, which is used to provide an inert environment in the furnace. The zonal method, which models radiative transport between finite zones in a participating medium, has been employed to compute the radiative heat transfer in the glass. The flow of glass due to the drawing process is modeled with a prescribed free-surface neck-down profile. The numerical results are compared with the few that are available in the literature. The effects of important physical variables such as draw speed, purge gas velocity and properties, furnace temperature, and preform diameter on the flow and the thermal field are investigated. It is found that the fiber drawing speed, the furnace temperature, and the preform diameter have significant effects on the temperature field in the preform/fiber, while the effects of the purge gas velocity and properties are relatively minor. The overall heating of the preform/fiber is largely due to radiative transport in the furnace and the changes needed in the furnace temperature distribution in order to heat the glass to its softening point at high speeds are determined.

Effects of Variable Properties and Viscous Dissipation During Optical Fiber Drawing

1996 ◽  
Vol 118 (2) ◽  
pp. 350-358 ◽  
Author(s):  
S. H.-K. Lee ◽  
Y. Jaluria
Keyword(s):  
Optical Fiber ◽  
Viscous Dissipation ◽  
Variable Viscosity ◽  
Free Surface Flow ◽  
Fused Silica ◽  
Surface Flow ◽  
Variable Properties ◽  
Fiber Drawing ◽  
Optical Fiber Drawing ◽  
Considerable Impact

The axisymmetric free-surface flow and thermal transport of fused silica during optical fiber drawing was considered with variable properties, prescribed heat flux, and neck shape. Experimental data from previous researchers were adapted or used as the basis for assumptions in order to enable a realistic analysis. The main objectives were to model the neck-down process in order to clarify the effects of the variable properties and the associated viscous dissipation. Due to the large changes in dimension and viscosity, this system poses severe nonlinearities, and a new solution algorithm was necessarily developed. Validation was achieved and several important results were obtained. Among these, it was shown that the viscous dissipation has considerable impact on the fiber temperature due to its localization to a small volume near the fiber section. Also, it was shown that a variable viscosity generated vorticity, which was localized to the region where the preform radius undergoes large changes.

Development of Superplastic Dieless Drawing Apparatus for 3Y-TZP Zirconia Ceramic Tube

2016 ◽  
Vol 838-839 ◽  
pp. 597-602 ◽  
Author(s):  
Tsuyoshi Furushima ◽  
Yutaro Hirose ◽  
Kazuo Tada ◽  
Ken-Ichi Manabe
Keyword(s):  
Tensile Deformation ◽  
Local Heating ◽  
Zirconia Ceramic ◽  
Outer Diameter ◽  
Drawing Process ◽  
Ceramic Tube ◽  
Drawing Speed ◽  
Dieless Drawing ◽  
Feeding Speed ◽  
Reduction In Area

A novel superplastic dieless drawing technique with local heating and tensile deformation has been focused on for fabrication of zirconia ceramic tube. In this study, 3Y-TZP zirconia ceramic tube with outer diameter of 6mm and inner diameter of 4mm as a superplastic material is used experimentally. An apparatus of superplastic dieless drawing with rotary stage for circumferential uniform heating and acetylene burner for high temperature of 1700°C is developed. The superplastiac dieless drawing experiment is carried out to investigate the effect of the ratio of drawing speed to feeding speed on the flexible controllability of diameter after drawing process. As a result, the reduction in area after drawing process can be controlled by the ratio of drawing speed to feeding speed. In addition, a maximum reduction in area of 79.2% can be realized in this process. Consequently, the validity of developed apparatus of superplastic dieless drawing for Zirconia ceramic tube can be demonstrated.

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