基于多相流的LCM工艺气泡生成仿真

Numerical simulation on bubble formation of LCM process based on multiphase flow

分析了液体模塑成型工艺(LCM)下织物预成型体中双尺度流动以及由此造成的空气裹入,进而产生细观及微观气泡的现象。基于多相流(VOF)方法建立了树脂空气两相流体在单胞内部流动的数学模型,并确定了该模型中多孔介质阻力源项和毛细力源项的具体形式。基于Fluent软件的UDF功能实现了上述两相流模型的数值求解,研究了平纹织物单胞中的两相流动以及2种气泡的生成过程。对Rovcloth 2454织物的气泡生成仿真结果显示,毛细数Ca对气泡的产生有决定性作用:当毛细数接近临界毛细数Cac时,气泡产生量最低,而当Ca小于Cac时,容易产生细观气泡,反之容易产生微观气泡。通过与文献中的理论预测和实验数据对比,验证了本文算法的正确性。

The dual-scale flow and the air entrapment in the preform which cause the meso and micro bubbles formation during liquid composite molding(LCM)process were analyzed.On the basis of volume of fluid(VOF)method,the mathematical model of the resin air two-phase flow in a unit cell was established,and the porous medium resistance and capillary force source term in the model were determined.The numerical simulation method of the above-mentioned mathematical model was implemented based on the UDF function of Fluent software,and the dual-scale flow and bubble formation of the plain woven unit cell was simulated.According to the simulation results on the Rovcloth 2454 fabric,capillary number has a critical role in the bubble formation,the critical capillary Cac,at which the micro and meso bubble content is minimal,is exist.When the Cais lower than Cac,meso bubbles are formed.At Ca higher than Cac,the micro bubbles are favored easily.The results were compared with the experimental data,and the feasibility of the simulation method was verified.