环状出口气泡雾化喷嘴液膜破碎过程与喷雾特性

主要研究了环状出口气泡雾化喷嘴出口下游液膜破碎过程与喷雾特性．当气液质量流量比为零时，出口下游形成空心封闭膜壳，表面波明显存在于液膜表面．随着气液质量流量比的增加，膜壳逐渐膨胀并在最薄弱部位被撕裂．利用DualPDA测量得到液雾颗粒的速度分布、直径分布与流通量分布特性；在主流区域存在负向运动的粒子同时颗粒平均速度明显降低．出口下游的速度分布曲线呈现双峰趋势，实验数据显示中心回流区域结束于距离出口30mm左右．索特平均直径的有关数据显示气泡的“爆炸”发生于出口下游5～15mm区域．流通量分布曲线也是双峰的，径向逐渐扩张，轴向逐渐降低，并且液雾主流区域流通量明显高于边缘区域的流通量．

Studies on Breakup of Liquid-Sheet and Spray Characteristics Downstream of the Annular-Spout Effervescent Atomizer

The breakup and atomization processes of liquid-sheet downstream the annular-spout effervescent atomizer were studied in this paper. When the mass flow-rate of air is zero, the liquid-sheet forms closed hollow shell. Wavy can be seen on the surface of liquid sheet distinctly. With the increasing of the mass flow-rate of air, the hollow shell expands and then collapses. Velocity profile, drop-size distribution and flux profile downstream of the annular-spout effervescent atomizer were measured with DualPDA. Near the main flow of spray, there are many drops with negative velocity and the average drop-size decreases distinctly at the same time. The velocity profile was found to be double peak shaped downstream of the atomizer exit. Experimental results reveal that the recirculation zone disappears at 30 mm down the spout.The experimental results of distribution of the Sauter mean drop size (SMD) that the bubbles "explode" at 5 to 15 mm down the spout. That means the secondary atomization is accomplished instantly.Flux profile is also double peak shaped. Those curves of flux expand in radial and fall in axial, and the flux is highest in main flow-field and lower in the rims.