采用CFD(computational fluid dynamics,计算流体力学)软件系统研究超音速气雾化喷嘴两相流的雾化过程.利用VOF(volume of fluid,流体体积)函数两相流模型模拟验证金属液不同质量流率下的2种初级破碎模式,并研究雾化压力和液体表面张力对金属液初级破碎过程的影响.模拟结果表明:金属液质量流率较小(0.053 kg/s)时,初级破碎模式为液膜破碎,金属液质量流率较大(0.265 kg/s)时,初级破碎模式为"微型喷泉"破碎;随雾化压力从0.5 MPa增加到1.5 MPa,初级破碎程度加剧,但雾化压力过高反而会削弱雾化效果;将金属液表面张力由1.2 N/m降至0.4 N/m,初级破碎时能够获得尺寸更细小的液滴,通过随后的二次破碎形成更加均匀细小的液滴,从而获得高质量的沉积锭.%The atomization process of gas-liquid two-phase flows in ultrasonic gas atomizer was analyzed using computational fluid dynamics software.The two kinds of primary-breakup models of liquid metal at different mass flow rates were verified by volume of fluid model,and the effects of atomizing pressure and liquid surface tension on the primary-breakup process were also studied.The simulation results indicate that the transformation of primary-breakup model will occur with decreasing the liquid mass flow rate.When the liquid mass flow rate is 0.053 kg/s,the primary breakup model is melt sheet,but when it is 0.265 kg/s,the primary breakup model is "fountain".When the atomizing pressure increases from 0.5 MPa to 1.5 MPa,the primary-breakup degree aggravates.However,excessive atomizing pressure will weaken the atomization effect.The smaller-size drop can be formed in the primary-breakup process when the surface tension of liquid metal decreases from 1.2 N/m to 0.4 N/m.Through the following secondary-breakup,more uniform and finer powder particles and high-quality as-spray ingot will be obtained.
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