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

Application of Atmospheric Pressure Chemical Vapor Deposition (APCVD) to the production of thin film coated glass is addressed in this study. Several layers of thin solid film are deposited on the surface of the glass as it moves underneath the APCVD applicator system at high temperature. High velocity in the vicinity of the deposition zone is desirable. Two separated regions of recirculating fluid are generated as the fluid jet exits the injector. The memory effect in the form of thickness streaks, corresponding to the location of the inlet holes located upstream in the upper manifold feed channel, are evident on the thin film. Also, the velocity field in the injector channel is influenced by the location of the holes. This nonuniform gas flow 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, premature reaction is to be avoided. Optimum design parameters include the dimensions of the applicator and the sensitivity of the flow field to boundary conditions. The Computational Fluid Dynamics (CFD) simulation and analysis package FIRE® is used to predict the flow. The flow of the gases involved is treated as that of a steady, viscous, incompressible fluid. The flow in the narrow injector channel is laminar and fully-developed with a Reynolds number of approximately 368. Results for both two- and three-dimensional cases demonstrate that the deposition process can be improved and that CFD techniques can be successfully used to predict the flow behavior.