An experimental and numerical study on the air entrainment phenomenon during the optical fiber coating process

2002 ◽  
Author(s):  
Shilai Liu
Keyword(s):  
Optical Fiber ◽  
Numerical Study ◽  
Air Entrainment ◽  
Coating Process ◽  
Fiber Coating

A Numerical Investigation of the Free Surface Flow During Optical Fiber Coating Process

2001 ◽  
Author(s):  
C. S. L. Liu ◽  
S. H.-K. Lee
Keyword(s):  
Contact Angle ◽  
Free Surface ◽  
Optical Fiber ◽  
Dynamic Contact Angle ◽  
Air Entrainment ◽  
Dynamic Contact ◽  
Coating Process ◽  
Coating Quality ◽  
Fiber Coating ◽  
Drawing Speed

Abstract Optical fiber has increasingly played a crucial role in the information transmission area nowadays. The elevated demand makes it necessary to manufacture high quality light-guide fibers that have proper mechanical properties to endure the stresses induced during installations and operations. Optical fiber coating process provides a protection layer to shield the fiber from surface abrasion and also to increase the fiber’s tensile strength. However, there are problems encountered during this process which reduce the coating quality. One of the major problems is air entrainment, which may lead to eccentrical or incomplete coating. Apparently, it is of great interest to study this problem to improve the coating quality. Many experimental studies have been performed on the dynamic contact angle, air entrainment velocity and their correlation with various parameters, such as the viscosity and the surface tension of coating materials, fiber drawing speed, etc. Nevertheless, how the coating flow affects the upper meniscus (directly related with dynamic contact angle and air entrainment) has not been intensively studied. Understanding of the effects is essential to improve the coating quality. To fulfill this requirement, the present work focused on investigating the relation of upper meniscus and fiber drawing speed. This is just the first part of the serial study on the optical fiber coating process. Firstly, a numerical code was developed with finite volume formulation. The results showed that the code had the capacity to deal with this free surface fluid flow problem. The simulated free surface shape was validated with experimental data available. The trend of the upper meniscus shape and dynamic contact angle developments at high drawing velocity was simulated. The results showed, as expected, that the dynamic contact angle would approach 180° with the increase of the fiber-drawing speed.

scholarly journals Manufacturing of Double Layer Optical Fiber Coating Using Phan-Thien-Tanner Fluid as Coating Material

Coatings ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 147 ◽  
Author(s):  
Zeeshan Khan ◽  
Haroon Ur Rasheed ◽  
S.O. Alharbi ◽  
Ilyas Khan ◽  
Tariq Abbas ◽  
...  
Keyword(s):  
Optical Fiber ◽  
Glass Fiber ◽  
Fiber Optics ◽  
Double Layer ◽  
Polymer Melt ◽  
Deborah Number ◽  
Coating Process ◽  
Polymer Flow ◽  
Fiber Coating ◽  
Ptt Fluid

Modern optical fiber required a double-layer resin coating on the glass fiber to provide protection from signal attenuation and mechanical damage. The most important plastics resin used in coating of fiber optics are plasticized polyvinyle (PVC), low/high density polyethylene (LDPE/HDPE), nylon, and polysulfone. Polymer flow during optical fiber coating in a pressure type coating die has been simulated under non-isothermal conditions. The flow dependent on the wire or fiber velocity, geometry of the die, and the viscosity of the polymer. The wet-on-wet coating process is an efficient process for two-layer coating on the fiber optics. In the present study, the constitutive equation of polymer flow satisfies viscoelastic Phan-Thien-Tanner (PTT) fluid, is used to characterize rheology of the polymer melt. Based on the assumption of the fully developed incompressible and laminar flow, the viscoelastic fluid model of two-immiscible resins-layers modeled for simplified-geometry of capillary-annulus where the glass fiber drawing inside the die at high speed. The equation describing the flow of the polymer melt inside the die was solved, analytically and numerically, by the Runge-Kutta method. The effect of physical characteristics in the problem has been discussed in detail through graphs by assigning numerical values for several parameters of interest. It is observed that velocity increases with increasing values of ε D 1 2 , ε D 2 2 , X 1 , and X 2 . The volume flow rate increases with an increasing Deborah number. The thickness of coated fiber optic increases with increasing ε D 1 2 , ε D 2 2 , and δ . Increase in Brinkman number and Deborah number enhances the rate of heat transfer. It is our first attempt to model PTT fluid as a coating material for double-layer optical fiber coating using the wet-on-wet coating process. At the end, the present study is also compared with the published work as a particular case, and good agreement is found.

Conjugate Heat Transfer in an Optical Fiber Coating Process

2005 ◽  
Author(s):  
Sang-Yeoun Yoo ◽  
Yogesh Jaluria
Keyword(s):  
Heat Transfer ◽  
Optical Fiber ◽  
Conjugate Heat Transfer ◽  
Fiber Surface ◽  
Ultra Violet ◽  
Thermal Conditions ◽  
Coating Process ◽  
Uv Curable ◽  
Fiber Coating

The optical fiber coating process in an axi-symmetric applicator and die system was simulated in this study. Various thermal conditions and process variables are investigated. Ultra-violet (UV) curable acrylates are used for the coating material, whose properties are highly dependent on temperature. Conjugate heat transfer is considered at the moving fiber surface since the fiber constantly exchanges energy with the contacting fluid. The temperature level in the applicator and die is found to increase with fiber speed, the increase being the highest in the die whose wall temperature is kept fixed. This high temperature rise is primarily due to the tremendous viscous dissipation within the fluid, especially in the die. It is important to avoid high temperatures in the fluid because the polymer starts to crosslink and degrade. The fiber temperature at the entrance was also found to be of substantial importance. This work can be used to improve the quality of the coating, particularly its uniformity, and the production rate.

scholarly journals Double-layer optical fiber coating analysis in MHD flow of an elastico-viscous fluid using wet-on-wet coating process

2017 ◽  
Vol 7 ◽  
pp. 107-118 ◽  
Author(s):  
Zeeshan Khan ◽  
Saeed Islam ◽  
Rehan Ali Shah ◽  
Muhammad Altaf Khan ◽  
Ebenezer Bonyah ◽  
...  
Keyword(s):  
Viscous Fluid ◽  
Optical Fiber ◽  
Double Layer ◽  
Mhd Flow ◽  
Coating Process ◽  
Fiber Coating

A Numerical Study of Dynamic Meniscus

2002 ◽  
Author(s):  
C. S. L. Liu ◽  
S. H.-K. Lee
Keyword(s):  
Free Surface ◽  
Numerical Study ◽  
Contact Point ◽  
Air Entrainment ◽  
Dynamic Contact ◽  
Surface Flow ◽  
Coating Material ◽  
Coating Process ◽  
Coating Flow ◽  
Phase Calculation

Air entrainment is one of the bottlenecks during high speed coating process. Numerous studies concerned with the mechanics of air entrainment in coating process have been reported during the last four decades. The difficulty in visualization of three-phase contact point due to small dimension made it a hard task to unveil the mechanism of air entrainment experimentally. In most numerical studies on free surface flow, the effect of air upon dynamic meniscus was usually neglected, which induced the coarse accuracy in air entrainment study. In the present study, the numerical simulation of free surface coating flow as well as airflow upon dynamic meniscus was given. The effect of several parameters, such as coating material viscosity, and coating cup geometry, especially airflow upon free surface on the dynamic meniscus, was studied. The results showed that the dynamic effects of air in the vicinity of dynamic meniscus should not be disregarded. The pressure near the dynamic meniscus, especially at the dynamic contact point in the coating flow simulation, was much smaller than the atmosphere pressure, while in the gas phase calculation, the value was larger than the atmosphere one at the same position. These results indicated another explanation of the mechanics of air entrainment: the low pressure in the vicinity of dynamic contact point in the liquid makes the gas dissolve easily into the coating material, and the gas flow will even break the dynamic meniscus when the pressure difference between the gas and liquid phase is large enough. The effects of several factors on pressure distribution at the dynamic meniscus were also presented.

Viscous Dissipation Effects on the Coating Resin Flow Characteristics in High-Speed Optical Fiber Coating Process

2015 ◽  
Vol 656-657 ◽  
pp. 496-499
Author(s):  
Kyoung Jin Kim
Keyword(s):  
Optical Fiber ◽  
High Speed ◽  
Viscous Heating ◽  
Coating Process ◽  
Operational Parameters ◽  
Fiber Drawing ◽  
Temperature Dependent Viscosity ◽  
Fiber Coating ◽  
Drawing Speed ◽  
Modern Mass

Since the fiber drawing speed continues to increase in the modern mass manufacturing of optical fibers, the effects of viscous heating on the coating liquid flow could be significant in the capillary coating die of optical fiber coating applicator. Present study investigates the viscous coating resin flows in the micron-sized channel of coating die with temperature dependent viscosity. The computational results find the substantial temperature increase near the die wall and plug-like velocity distribution due to localized viscous heating. Also, final coating thickness is affected by the change of coating die diameter when the fiber drawing speed is high. Thus, the design of glass fiber coating process at high drawing speed requires careful consideration of several key operational parameters.

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