配备下限流导液管的环缝喷嘴雾化能力研究

高品质金属粉末是众多制造领域中的基础材料，微细粉末成型的关键技术在于气雾化制备阶段，而喷嘴及导液管结构和雾化工艺参数对气雾化粉末的质量有重要影响。基于高速射流流体动力学的数值模拟方法研究了雾化压力、雾化气体温度、导液管下口直径与伸出长度对配备下限流导液管环缝喷嘴雾化能力的影响，通过喷盘流场检测验证模型的可靠性。结果表明：环缝喷嘴装配下限流导液管临界入口压力为128.1 kPa，雾化压力2.0 MPa时既能有效增大雾化腔内的气体最大速度和降低最低温度，又能防止过高压力造成返喷而影响气雾化顺行。此外，在极限雾化压力2.0 MPa下，通过增大雾化气体温度、下限流导液管下口直径由5 mm降低至1 mm以及伸出长度由0 mm增大至2 mm均能继续提升气液质量流速比而提升其雾化能力。生产实践也证实了模型的预瞻性，在此优化工艺下生产顺行且粉末粒度D50仅为23.84μm。

Study on the Atomization Ability of the Annular Slit Nozzle Assembly with the Delivery Tube of Lower-limiting Flow

High-quality metal powders are the basic material in many manufacturing fields, the key technology of microfine powder forming is in the stage of gas atomization, and the structural parameters of nozzle and delivery tube and the atomization parameters have a great impact on the quality of the powders from gas atomization. The effects of atomization pressure, gas temperature, lower port diameter and protrusion length on the atomization ability of annular slit nozzle assembled with delivery tube of lower-limiting flow are analyzed by numerical simulation based on high-speed jet flow fluid dynamics. The accuracy of the model is validated by the measurement device for fluid flow filed of the spray disc. The results show that the critical inlet pressure of the annular slit nozzle assembled with delivery tube of lower-limiting flow is 128.1 kPa and the atomization pressure is 2.0 MPa, which can not only effectively increase the maximum velocity of the gas in the atomization chamber and reduce the minimum temperature, but also prevent the backflow caused by too high pressure from affecting the atomization stability. In addition, at the ultimate atomization pressure of 2.0 MPa, the gas to metal ratio (GMR) can be increasing the atomization gas temperature, reducing the lower port diameter from 5 mm to 1 mm and increasing the protrusion length from 0 mm to 2 mm for the improvement of atomization ability. The production practice also confirmed the foresight of the model, the production is antegrade and the powder particle size D₅₀ is only 23.84 μm under this optimized process.