Simulation of unsteady thermal-flow field for modified chemical vapor deposition (MCVD) process

A three-dimensional unsteady thermal-flow coupling model for the modified chemical vapor deposition (MCVD) process is established in this work, and further the influence factors on the temperature field are extensively investigated. The results indicate that the axial wall temperature is significantly influenced by the maximum heat flux and torch speed, while the tube rotation speed and gas flowrate effects can be ignored. Generally, the temperature difference between inner and outer walls always exists, and can reach a maximum value of 169 K. Specially, it is also found that the circumferential surface temperature distribution of quartz tube appears non-uniform under the heating of oxy-hydrogen torch because of helical effect, and it is sensitive to the tube rotation speed. With increasing of the tube rotation speed, the maximum temperature difference of outer wall is reduced from 324 K to 249 K, and the maximum temperature difference of inner wall is reduced from 164 K to 65 K. Finally, the simulation results could provide theoretical basis for optimizing the operation parameters such that a uniform temperature field can be obtained to fabricate the optical fiber with high quality.