基于VOF方法的多孔陶瓷快速成型喷嘴流场数值分析
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摘要
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 0.001 m/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.
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 0.001 m/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.
引文
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[2]左开慧,姚冬旭,夏咏锋,等.应用于陶瓷材料的快速成型技术的发展[J].中国材料进展,2015,34(12):921-927.
[3]韩召,曹文斌,林志明,等.陶瓷材料的选区激光烧结快速成型技术研究进展[J].无机材料学报,2004,19(4):705-713.
[4]张永良,王宝瑞,孔文俊,等.离心喷嘴实验与流场结构的数值模拟[J].工程热物理学报,2013,V34(4):760-764.
[5]吴南星,朱金贵,张柏清.基于ANSYS变温场的真空练泥机泥料挤出质量的研究[J].陶瓷学报,2010,31(2):180-184.
[6]王成军,陈海耿,马金凤.基于VOF方法数值模拟离心式喷嘴内两相流流动[J].东北大学学报(自然科学版),2009,30(7):1005-1008.
[7]黄启龙,李进贤,郑亚,等.旋流式进料喷嘴实验与流场结构数值模拟[J].西北工业大学学报,2015(3):388-394.
[8]Belhadef A,Vallet A,Amielh M,et al.Pressure-swirl atomization:Modeling and experimental approaches[J].International Journal of Multiphase Flow,2012,39:13-20.
[9]Amini G.Liquid flow in a simplex swirl nozzle[J].International Journal of Multiphase Flow,2016,79:225-235.
[10]邱庆刚,贾丹丹,朱晓静,等.结构参数对离心喷嘴出口液膜厚度的影响[J].江苏大学学报(自然科学版),2015,36(3):271-275.
[11]潘阳敏,罗青,王丽雯,等.压力旋流式喷嘴喷淋液膜区换热过程的数值模拟[J].化工学报,2017,68(2):575-583.
[12]Hirt C W,Nichols B D.Volume of fluid(VOF)method for the dynamics of free boundaries[J].Journal of Computational Physics,1981,39(1):201-225.