Computational Fluid Dynamics Analysis of the Flow in an APCVD Applicator System

Application of Atmospheric Pressure Chemical Vapor Deposition (APCVD) to the production of coated glass is addressed in this study. Several layers of thin films are deposited on the surface of the glass as it moves underneath the APCVD applicator system at high temperature. A memory effect in the form of film thickness streaks, corresponding to the location of the inlet holes located upstream in the upper manifold feed channel, is evident on the glass. This nonuniform film across the glass causes a color variation of the coating. Effective mixing of the gas streams is required to treat the hole memory problem. However, a premature reaction is to be avoided. Optimum design parameters to correct this problem include the geometry of the applicator and the sensitivity of the flow field to boundary conditions is of major interest. The Computational Fluid Dynamics (CFD) simulation and analysis package FIRE is used to predict the flow. The flow of gases involved is treated as that of a steady, viscous, incompressible fluid. Results for both two- and three-dimensional cases demonstrate that the deposition process can be improved by injecting the flow at an angle counter to the direction of glass motion, and that CFD techniques can be successfully used to predict the flow behavior of an APCVD applicator system and help optimize its design.