摘要
吹气发泡法制备闭孔泡沫铝的过程实质上是搅拌流场中复杂的两相流动过程,应用计算流体力学方法分析由倾斜轴倾斜叶片引起的发泡熔池内气液两相强旋湍流流动过程.在双流体模型基础上引入多重参考系法描述搅拌两相流场,通过分析相间相互作用及湍流模型进行封闭.解气泡数密度函数的输运方程来分析气泡聚合和破碎引起的气泡尺寸变化.应用体积积分的方法,计算平均及局部气含率及气泡直径.考察了桨叶转速及气体流率对气泡直径及其分布的影响.结果显示,气含率随桨叶转速和气体流率增加而增大;气泡直径随气体流率增加而增大,随桨叶转速增大而减小.
The production process of aluminum foams by air injecting into molten aluminum composites is a highly complex two-phase flow with mechanical stirring. This work presents the results in Computational Fluid Dynamics simulations of gas-liquid turbulent flows induced by a pitched-blade turbine （four blades, 45 inclined） with a inclined shaft. A two fluid model incorporated with the Multi-reference Frame （MRF） method is used to predict the three-dimensional two-phase flow in the foaming tank. Bubble size distribution is also predicted by solving a transport equation for the bubble number density function, which accounts for break-up.and coalescence phenomena. Furthermore, the averaged total and local gas fractions and bubble diameters are predicted by means of volume integration. The influences of impeller rotational speed and gas flowrate on bubble diameter and distribution are examined. Computational results show that gas volumetric fraction increases with increasing gas flowrate and impeller speed, bubble size increases with increasing gas flowrate and decreasing impeller speed.
出处
《过程工程学报》
EI
CAS
CSCD
北大核心
2007年第5期889-894,共6页
The Chinese Journal of Process Engineering
关键词
泡沫铝
多重参考系
气液两相流
气含率
aluminum foam
multi-reference frame
gas-liquid flow
gas volumetric fraction
