基于VOF方法的多孔陶瓷快速成型喷嘴流场数值分析

VOF-Based Numerical Analysis of Flow Field of Nozzle in Rapid Prototyping of Porous Ceramics

为改善多孔陶瓷坯体中泥料开裂、分层现象,利用VOF方法和层流模型,以等效的二维网格模型对多孔陶瓷快速成型喷嘴流场进行数值分析,分析泥料进口速度对速度分布、压力分布和泥料体积分数的影响。结果表明：泥料进口速度为0.001 m/s时,喷嘴内速度分布均匀,没有出现空气涡;进口速度为0.002 m/s时,喷嘴内部存在压力差,在喷嘴轴线1/5处出现约占喷嘴总面积0.5%的空气涡;进口速度为0.003 m/s时,空气涡约占喷嘴总面积6%;数值分析和实验结果基本吻合,误差在12.5%以内,在用快速成型技术制备多孔陶瓷时,泥料进口速度需控制在临界值0.002 m/s以下。

In order to improve the cracking and delamination of pug in porous ceramic billet, the VOF method and laminar flow model were utilized, the flow field of porous ceramic rapid prototyping nozzle was numerically analyzed with equivalent two-dimensional mesh model, the influence of inlet velocity on velocity distribution, pressure distribution and pug volume fraction were being analyzed. The results showed that= when the inlet velocity of pug was 0.001m/s, the velocity distribution was even and did not appear air vortex, when the inlet velocity was 0.002 m/s, the difference of pressure arose inside the nozzle, there was an air vortex about 0.5% of the total area of nozzle that arose at the 1/5 position of the axis of nozzle; when the inlet velocity was 0.003 m/s, the air vortex accounted for 6% of the total area of nozzle approximately. The numerical analysis was in good agreement with the experimental results, the error was within 12.5%, in the preparation of making porous ceramics by rapid prototyping, the inlet velocity of pug should be controlled below the critical value of 0.002 m/s.