Transient numerical simulation of convection-driven flow field and temperature distribution of vapor deposition for material processing under microgravity conditions.

摘要

Convection in a 3-D co-axial cylinder at extremely low pressure environment of 10{dollar}sp{lcub}-2{rcub} mmHg{dollar} is modeled applying 3 different gravity levels, 1, 10{dollar}sp{lcub}-2{rcub}{dollar} and 10{dollar}sp{lcub}-4{rcub}{dollar} {dollar}gsb0 (gsb0=9.81 m/ssp2).{dollar} Using the vapor deposition from source materials driven by heat transfer process under normal and oblique directions of gravitational acceleration, a series of time-step animation of the initiation and development of flow and temperature profiles during the course of vapor deposition has been obtained through the numerical computation. It is obvious that there is no way to produce a homogenous thin crystalline film with fine grains under such a complicated flow pattern of recirculation with a non-uniform temperature distribution under normal gravitational acceleration. Vapor deposition under microgravity environment is favorable to produce a homogenous thin crystalline film. Results of numerical simulation verify these conclusions.