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紧耦合气雾化喷嘴流场特性研究

Research on flow field characteristic of close-coupled gas atomizing nozzles

  • 摘要: 雾化喷嘴作为紧耦合气雾化法制备金属粉末的核心部件,其导液管末端压力及滞留点处压力对雾化过程中金属熔液的顺利流出和破碎至关重要。当导液管末端为正压时,金属熔液无法顺利流出导液管,严重时会造成金属熔液的反喷现象;滞留点处压力越大,流出导液管的金属熔液所受到雾化气体的冲击力越大,其破碎效果越佳。本文通过数学建模、实验验证及数值模拟的方法研究了雾化压力、导液管伸长量及导液管锥顶角对其末端压力及滞留点处压力的影响。结果表明:随着雾化压力的增大,负压区域长度基本不变,而滞留点处压力增大;导液管伸长量的增加会使负压区域长度增加且滞留点处压力减小;随着导液管锥顶角的增大,其末端压力会从负压过渡成正压,从而导致雾化失败。

     

    Abstract: The atomization nozzle is the core component for the metal powder preparation by close-coupled gas atomization method. The pressure at the tip of the melt delivery tube and the stagnation point is very important for the smooth outflow of the molten metal during the atomization process. When the tip of the melt delivery tube is positive pressure, the molten metal cannot flow out of the nozzle smoothly, and in severe cases, it may cause the back spray of the molten metal. The greater the pressure at the stagnation point, the greater the impact force of the atomized gas acting on the molten metal flowing out of the melt delivery tube, and the better the crushing effect. The effects of atomization pressure, protrusion length, and cone-apex angle on the pressure at the tip of the melt delivery tube and the stagnation point were studied by mathematical modeling, experimental verification, and numerical simulation in this paper. The results show that, with the increase of atomization pressure, the length of the negative pressure area remains basically unchanged, while the pressure at the stagnation point increases. With the increase of the melt delivery tube elongation, the length of the negative pressure area increases and the pressure at the stagnation point decreases. With the increase of the cone-apex angle of the melt delivery tube, the pressure at the tip of tube changes from the negative to the positive, resulting in the failure of atomization.

     

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