Numerical Simulation of Mixing Uniformity for Dynamic Mixer of Vacuum Injection Machine
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摘要: 在真空状态下,为将混合时间尺度小、粘度较高的不同液体快速均匀混合,提出了一种带有挤压槽轮和搅拌叶轮的动态混合器,介绍了这种动态混合器的结构原理和混合机理。基于FLUENT中的动网格模型、Mixture多相流模型、RNG κ-ε湍流模型及PISO算法,对混合器预混合管道不同出口位置、叶片数量、叶轮转速等不同条件下的两相流混合效果进行了数值模拟,结果表明:预混合管道出口位置不同时,混合效果不同;当叶片数量为16时,混合效果最理想;模拟还表明,增加叶轮旋转速度对混合效果作用明显,但是达到一定转速后,混合效果趋于稳定。在此基础上,通过液体质点运动矢量图、速度流线图和湍动强度分布云图,分析了加速溶液混合均匀的是叶轮二次剪切和混合器中运动部件对流场的湍动作用,选用环氧树脂(E51)与对应的固化剂进行混合并浇注成型,并对制品的硬度进行了测试,实验结果表明该混合器混合性能可靠。Abstract: A kind of dynamic mixer with extrusion sheave and stirring impeller is designed to achieve uniform mixed performance for the short mixing time and different high viscosity liquids in vacuum state. The structure principle and mechanism about mixer are introduced. Mixture multiphase model, RNG κ-ε model and PISO algorithm are adopted in FLUENT software to obtain the simulation result for different outlet location of mixer premixed pipe, blades number, impeller speed. The results show that there are different mixing performance when the premixed pipe outlet location is changed, the mixer has its best mixing performance if the blades number is sixteen. The mixing performance has good effect as the rotational speed is increased at the same time, but the mixing performance will have steady state when it obtains certain speed. On this basis, the secondary shear effect from impeller and turbulence function of moving parts for flow field in mixer can accelerate liquid mix, according to the velocity vector of liquid particle, the distribution of flow streamline and the cloud chart of turbulent intensity contours. We choose Epoxy resin (E51) and the corresponding curing agent to mix for a mould, and the hardness of the production was tested. The experimental results show that this dynamic mixer has reliable mixing performance.
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Key words:
- vacuum casting machine /
- dynamic mesh /
- dynamic mixer /
- mixing performance /
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