单液滴羽状/液膜稀释破碎特性研究

Experimental Investigations of Breakup Characteristic of Single Droplet in Plume/Sheet-Thinning Breakup Regime in Airflow

关键词:  液滴  雾化  热气流  喷雾  高速摄像机

Key words:  Droplet  Atomization  Heated air flow  Sprays  High-speed cameras

摘要:

为了获得气流中单液滴羽状/液膜稀释破碎特性，采用高速摄像机对液滴变形、破碎过程进行了捕获。实验结果表明:液滴的变形时间小于其破碎时间，且都随气动力增加呈负增长的变化趋势，其变化梯度、相同气动力下特征时间也都随液滴初始直径的增加而有所增加；液滴破碎区域面积随气动力增加呈先增加后减小再增加的变化趋势，且随液滴初始直径增加，液滴破碎区域面积也随之增加；破碎区域中子液滴质量百分数随气动力增加而增加，且随液滴初始直径增加而减小，其值变化的范围为0.48～0.66；液滴的破碎程度随气动力、液滴初始直径的增加而增加；破碎区域中子液滴细度与液滴初始细度的比值在0.18～0.23之间变化；在羽状/液膜稀释破碎阶段，多元线性回归理论可以用于建立子液滴数目、SMD的数学模型。

Abstract:

In order to obtain characteristic of single droplet in the plume/sheet-thinning breakup regime in airflow，the high-speed cameras were applied to measure single droplet deformation and breakage. Experimental results show that the character time of droplet breakup had a negative relationship with the aerodynamics，while its value and change gradient were both positively associated with the original droplet diameter，and the deformation time was less than the broken time. The area of droplet breakup increased but then changed to decrease and increased again with the increase of aerodynamics，and the area of droplet breakup increased as the increase of original diameters. The percentage of sub-droplet mass increased with the increase of aerodynamics，but it decreased as the increase of original diameters，and its value changed between 0.48～0.66. The level of droplet breakup was significantly improved as the increase of droplet original diameter and the aerodynamics. The ratio of sub-droplet fineness and initial droplet fineness varied between 0.18～0.23. The multivariate linear regression analysis method could be used to establish the mathematical model of the number and sauter mean diameter (SMD) of sub-droplet，in the plume/sheet-thinning breakup regime.