超声强化液相中纳米SiO_(2)分布特性的CFD-PBM数值模拟

Numerical Simulation of Distribution Characteristics of Nano-SiO_(2) in Ultrasound-enhanced Liquidoid by CFD-PBM

纳米粒子均匀分散对于纳米复合材料应用在航空航天、汽车等领域具有重要意义。依据目前超声强化纳米粒子固液混合过程中数值模拟存在的不足,基于群体平衡模型建立了考虑颗粒聚并与破碎作用的超声分散过程动力学模型,并采用CFD-PBM耦合的方法对不同超声探头位置、颗粒质量分数、颗粒尺寸下的纳米SiO_(2)颗粒分布特性进行了数值研究。结果表明:该模型能较好描述纳米SiO_(2)颗粒经超声分散后的粒径分布情况;在一定超声探头位置范围内,h对纳米SiO_(2)颗粒分散影响较小;在超声探头位置h=10mm,质量分数为0.1%的悬浮液中颗粒分散更为均匀;此外,SiO_(2)颗粒初始平均粒径越大,其分布越均匀。

The uniform dispersion of nano-particles is of great significance for the application of nano-composite materials in aerospace,automobile and other fields.Based on the shortcomings of numerical simulation of solid-liquid mixing process of ultrasonic enhanced nanoparticles,a dynamic model of ultrasonic dispersion process was established based on the population equilibrium model considering particle coalescence and fragmentation.The distribution characteristics of nano-SiO_(2) particles under different ultrasonic probe positions,particle mass fraction and particle size were numerically studied by CFD-PBM coupling method.The simulation results show that the model can describe the size distribution of nano-SiO_(2) particles after ultrasonic dispersion.In a certain range of ultrasonic probe position,h has little influence on the dispersion of nano-SiO_(2) particles.In the ultrasonic probe position h=10 mm,the particle dispersion is more uniform in the suspension of 0.1%mass fraction;In addition,the larger the initial average size of SiO_(2) particles is,the more uniform the distribution is.