Analysis of Irradiator Tube Purging for Fiber Drawing.

This paper presents the numerical and experimental investigation of fluid flow and mass transfer in an irradiator tube. After applying the synthetic coating material for cushioning and protection, optical fibers or wires are drawn through a glass tube where UV light from the surrounding irradiators cause curing of the coating material. During this curing process, fumes are generated, which needs to be flushed out of the tube before it diffuses to the glass wall and causes tube smoking, a problem faced by the industries. Analytical calculations are first done to study the effect of laminar and turbulent flow, flow rate and tube diameter. Numerical simulation for the purging air flow and mass transfer of the generated chemical species is then done using a computational model and results presented. Irradiator tube flows with regular and enhanced lip at exit and without lip are all simulated. The mass concentration of generated species near the tube wall is found high for regular and extended lip (causes tube smoking), but low for no lip (suggests no smoking and hence desirable). Computations are also done for larger tube diameter, which gives lowest species concentration. Experiments are performed and they support the simulated results. [ABSTRACT FROM AUTHOR]