毛细管静电雾化模式与力学过程分析

Electro-spraying modes from capillary and mechanical analysis

采用带有显微变焦镜头的高速摄像技术对无水乙醇在不锈钢单毛细管产生的静电雾化现象进行了可视化研究.基于毛细管末端形成的弯月面、微射流或雾滴分散形态,获得了无水乙醇的静电雾化模式及其转变过程,典型的雾化模式有滴状、微滴、纺锤、摆动射流、旋转射流、锥射流及多股射流等.通过分析不同雾化模式下微射流与雾滴的受力,探讨了微射流和雾滴的运动形态与雾化模式及受力之间的关系.试验结果表明:毛细管静电雾化模式与电压紧密相关,随着电压的增加,雾化模式逐渐从滴状、纺锤模式过渡为射流及多股射流模式,呈现较为有序的过渡;在不同的雾化模式下,微射流或雾滴受到的重力、电场力、阻力、表面张力及介质电泳力和变形力对微射流形态或雾滴运动轨迹有着不同程度的影响;在较低的电场强度下产生静电雾化过程中,电场力作用较小,重力占主导地位,雾滴在表面张力的作用下呈现球形或椭圆形;在较高的电场强度下产生的静电雾化过程,电场力占主导地位,雾化模式在不同性质电场力的作用下呈现出多样性.

Based on microscopic high-speed camera technology,the electro-spraying visualization of anhydrous ethanol was investigated in stainless steel single-capillary. Based on the outlet of capillary meniscus and the formation of micro-jet or droplet morphology,the electro-spraying modes of anhydrous alcohol and the transformation process were analyzed. The typical spraying-modes include dripping,micro-dripping,spindle,multi-spindle,oscillating-jet,precession-jet,cone-jet and multi-jet modes. The forces acting on micro-jet and droplets under different spraying-modes were analyzed,and the relationship between force and motion pattern of micro-jet,droplet and spraying-modes was discussed. The results indicate that the capillary electro-spraying modes are closely associated with applied voltage. With the increasing of voltage,the electro-spraying modes gradually transform from dripping,spindle modes to cone-jet and multi-jet modes with orderly transition. For different electro-spraying modes, gravity,electric field force,resistance,surface tension,dielectric electrophoretic force and deformation force play different roles on motion pattern and trajectory of micro-jet or droplet. For low electric field strength,thegravity dominates the droplet motion,and the droplet becomes spherical under the surface tension. For high electric field strength,the electric field force dominates the motion of micro-jet or droplets,and it shows various electro-spraying modes under different electric forces.