Numerical studies on heat and mass transport during large-sized fused silica glass synthesis by multi-burner chemical vapor deposition

Abstract

With the development of modern optical systems towards large scale, the fused silica glass with a large size is receiving increasing attention. In this paper, multi-burner chemical vapor deposition technique was proposed to synthesize the large-sized fused silica glass, and an integrated computational model was used to describe the fluid flow, combustion and heat transfer in the furnace. The effects of various process parameters on the distributions of temperature and species were investigated. Based on the evaluation of temperature and key species concentrations on deposition surface, the size and quality of the synthesized fused silica glass were indirectly estimated. Results showed that reducing the deposition surface height and increasing the number of burners could improve the temperature and species concentrations on the deposition surface, while an increase in the number of furnace outlets led to their decreases. The use of two burners would lead to the formation of discontinuous glass regions at the current conditions and a circular glass structure was generated when employing three burners and deposition surface height of 0.5 m, based on the proposed temperature criterion. The combined process parameters of four burners, deposition surface height of 0.5 m, H2/O2 equivalence ratio of 1.00 and two furnace outlets are be of advantage to synthesize the large-sized and high-quality fused silica glass at current sizes and structures of the furnace and burner.