摘要针对干法造粒制备Si3N4颗粒过程,基于流体体积函数(volume of fluid,VOF)方法,采用湍流模型中可实现的k-ε模型(k为湍流动能,ε为耗散率),模拟计算喷嘴入口的倾斜角度α对空气芯、雾化锥角和喷嘴出口处黏结液速度的影响,并采用干法造粒制备Si3N4陶瓷颗粒进行实验验证。计算结果表明：随倾斜角度α从0°增大到30°,喷嘴内空气芯区域面积由约占总面积的18%增大到25%,空气芯的平均直径增大,同时喷嘴出口处的黏结液速度梯度由4.43~5.06 m/s增大到5.69~6.32 m/s,雾化锥角由63°增大到74°,从而加快黏结液膜的破碎过程;而当倾斜角度增大到45°时,空气芯的平均直径、喷嘴出口处黏结液的速度和雾化锥角都最小。实验结果表明,雾化喷嘴的入口倾斜角度为30°时,Si3N4颗粒粒度最细。数值分析结果与实验结果吻合良好。
Abstract：In the process of preparing Si3N4 particles by dry granulation, volume of fluid (VOF) method and realizable k-ε model (k is turbulent kinetic energy, ε is dissipation rate) in turbulence model were used to simulate and calculate the influence of the deflection angle α of the nozzle inlets on air core, atomization cone angle and adhesive velocity at nozzle outlet. The experimental verification of Si3N4 ceramic particles prepared by dry granulation was carried out. The results show that when the deflection angle α increases from 0° to 30°, the area of air core in nozzle increases from about 18% to 25%. The mean diameter of air core increases, and the velocity gradient of binder at nozzle outlet increases from 4.43-5.06 m/s to 5.69-6.32 m/s. The spray cone angle increases from 63° to 74° and then the breakup process of the liquid film can be accelerated. When the deflection angle increases to 45°, the average diameter of the air core, the velocity of adhesive at the nozzle outlet and the atomization cone angle are the minimum. The experimental results show that the particle size of Si3N4 is the smallest when the deflection angle of atomizer is 30°. The numerical results are in good agreement with the experimental results.
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2020, Vol. 25 
