Accelerated Cooling of Optical Fiber
- PDF / 333,092 Bytes
- 6 Pages / 414.72 x 648 pts Page_size
- 78 Downloads / 249 Views
ACCELERATED COOLING OF OPTICAL FIBER S. KYRIACOU*, C.E. POLYMEROPOULOS* AND V. SERNAS* and *Rutgers University, Dept. of Mechanical Engineering, P.O. Box 909, Piscataway, New Jersey 08855,
Aerospace U.S.A.
ABSTRACT A novel apparatus for accelerated cooling of optical fiber has been used at different fiber speeds using Nitrogen and Helium The gas flow was counter to the direction as the cooling gases. of the fiber motion inside a small diameter tube. The experimental results show significant improvement over natural cooling, as well as over available transverse cooling. INTRODUCTION One of the problems encountered in high speed drawing of optical fiber is the resulting high temperature at the coating cup location. This is because as the drawing speed increases the rate of heat loss by natural cooling from the fiber to the relatively is not adequate for reducing the stagnant ambient environment fiber temperature to a sufficiently low value for maintaining the integrity of the coating substance. This problem can be overcome by using a high drawing tower, or by employing some method of forced cooling of the fiber. A forced cooling apparatus using a transverse gas jet has been described by Paek et al.(l). Transverse jet cooling using a cooling gas such as helium, with better heat transfer characteristics than air, is available with commercial draw towers such as the one used in the present work. however, limited to the The extend of transverse jet cooling is, use of relatively short cooling sections because of lateral fiber Jochem et vibrations resulting from the transverse gas motion. al. (2) passed the fiber through a water cooled tube which was continuously flushed with a low flow rate of cooling gas thus enabling a choice in the type of ambient gas environment for the fiber. The results showed significant improvement in fiber cooling by changing the cooling gas from air to helium. The present work deals with the description and testing of a new fiber cooling apparatus that employs a well controlled cooling gas flow in the annular region between the cooling section wall The and the fiber, which moves counter to the gas flow direction. choice of a small outer diameter annulus and counterflow configuration results in better mixing and heat transfer from the fiber. In addition, the geometry and knowledge of flow configuration offer the possibility of analytical predictions and comparisons with experimental findings. EXPERIMENTAL APPARATUS Figure 1 shows a schematic diagram of the fiber cooling apparatus used. The main cooling section consisted of a water cooled brass tube 50cm long and 4mm inside diameter. It was connected to two 12cm inside diameter and 6.5cm long plenum chambers whose purpose was to maintain the necessary static pressure difference for the desired cooling gas flow. For this purpose the downstream (top) vacuum plenum chamber was kept below ambient pressure using the pump shown in Fig. 1, while the upstream (bottom) plenum chamber
Mat. Res. Soc. Symp. Proc. Vol. 172. @1990 Materials Research Society
Data Loading...
