气体雾化过程中涉及颗粒形貌和空心颗粒形成的金属液滴变形和破碎数值模拟

Numerical simulation on metallic droplet deformation and breakup concerning particle morphology and hollow particle formation during gas atomization

采用考虑液滴冷却和凝固的流体体积(VOF)方法模拟金属液滴在气体雾化过程中的变形和破碎。建立典型粉末形貌和液滴破碎行为之间的相关性,以指导球形粉末颗粒的制备。结果显示,当增加液滴的气动力与黏性力的比值时,球形颗粒的形成得到加强;然而,当减小这个比值时,预期的液滴破碎模型将被改变或仅仅只发生液滴的变形。从空心颗粒的形成和演变过程的数值模拟中观察到几种典型的情况,例如,开放的空心液膜的形成、液膜封闭、气泡的离心和气泡的脱离。通过提高气体速度或液滴温度,实现较高的非平衡拉普拉斯压力或较低的粘性力,促使气泡从液滴内部分离。

The deformation and breakup of metallic droplets during gas atomization were simulated using a volume of fluid(VOF)approach that considered droplet cooling and solidification.The correlation between the typical powder morphology and droplet breakup behavior was established to guide the preparation of spherical powder particles.The results showed that upon increasing the ratio of aerodynamic to viscous force of the droplet,the formation of spherical particles was enhanced,while upon decreasing this ratio,the expected droplet breakup mode changed or only droplet deformation occurred.Several typical scenarios were observed from the numerical simulations of the hollow particle formation and evolution process,e.g.,open hollow film formation,film closure,bubble centrifugation,and bubble detachment.By increasing the gas velocity or droplet temperature,a higher non-equilibrium Laplace pressure or lower viscous forces was achieved,which separated the bubbles from the interior of the droplet.