Study on Characteristrics of Nanopowder Continuous High Pressure Dispersing System
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摘要: 搭建了一种超微颗粒连续分散装置，实验发现纳米颗粒经连续喷射分散可被分散至初级粒径范围。为探讨该装置的机理及高压分散特性，数值模拟了纳米粉体的二级喷射分散过程。结果表明，数值与实验结果的压力动态曲线相符，颗粒数密度沿流动方向降低，实验数据较模拟结果更低。颗粒高压分散的喷嘴不宜过长，以避免颗粒在喷嘴内流动过程中再次团聚，喷嘴长径比在2.5左右可在射流出口产生最大的剪切率，获得最佳的颗粒分散效果。Abstract: A continuous dispersing device for deagglomerating ultrafine particles is established. The experimental results show that nanoparticles can be dispersed to the primary particle size range via a continuous jet dispersion system. In order to investigate the mechanism and high-pressure dispersion characteristics of high pressure dispersion, the secondary jet dispersion of dry-powder nanoparticles was modeled and numerical simulated. The results show that numerical results of dynamic pressure profile agree with experiments. The particle number density decreases along the flow direction, and the experimental data is lower than the simulation results. The high pressure dispersing nozzle should not be too long to avoid re-agglomeration of the particles when passing through the nozzle. The aspect ratio of nozzle near 2.5 can produce the maximum shear rate at the jet outlet to obtain the best particle dispersion effect.
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Key words:
- nanoparticles /
- computational fluid dynamics /
- compressible flow /
- pressure /
- aspect ratio
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表 1 二级分散前各计算域的无量纲初始矩值
初始矩值 高压腔体 喷嘴 收集气袋 $m_{00}^*$ 1 1.0×10−6 1.0×10−6 $m_{10}^*$ 1 1.0×10−6 1.0×10−6 $m_{20}^*$ 22.107 22.107×10−6 22.107×10−6 
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