Research on flow field characteristic of close-coupled gas atomizing nozzle
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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大小对雾化过程中金属熔液的顺利流出至关重要。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方法研究了不同雾化压力、导液管伸长量、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 of the close-coupled gas atomization method to prepare metal powder. The pressure at the tip of the melt delivery tube and the pressure at the stagnation point are very important for the smooth outflow of the molten metal during the atomization process. When the tip of the melt delivery tube is under positive pressure, the molten metal cannot flow out of the nozzle smoothly, and in severe cases, it will 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. In this paper, the effects of atomization pressure, protrusion length and cone-apex angle on the pressure at the tip of the melt delivery tube and the pressure at the stagnation point are studied experimentally and numerically. The results show that with the increase of atomization pressure, the length of the negative pressure zone remains basically unchanged, while the pressure at the stagnation point increases; Increased protrusion length expands the negative pressure zone and reduces the pressure at the stagnation point; As the cone-apex angle of the melt delivery tube increases, the pressure at the tip of the tube will transition from negative pressure to positive pressure, resulting in the failure of atomization.
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Key words:
- nozzle /
- close-coupled gas atomization /
- numerical simulation /
- melt delivery tube
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