平面液膜破碎及雾化过程的试验研究

Experiment Research on Break-Up and Atomization Process of Planar Prefilm

关键词:  平面液膜  破碎过程  可视化研究  液膜形态  雾化粒径

Key words:  Planar prefilm  Break-up process  Visualization investigation  Prefilm shape  Atomization size

摘要:

为考察液膜破碎及雾化特性，通过高速相机、平面激光诱导荧光（PLIF）和相位多普勒粒子分析仪（PDPA）对平面液膜的失稳、破碎及雾化全过程进行了试验研究。结果表明，平面液膜在预膜板上的液膜形态与气液速度比（λ）直接相关。随着气液速度比增大，平面液膜分别会呈现平滑表面（λ≤23）、波动表面（23<λ<70）和液膜剥离（λ≥70）三种形态。此外，平面液膜破碎过程中会形成叶瓣状、波纹状、孔状和韧带状的液带，液带形状主要取决于气流和液体速度。液膜破碎过程的破碎距离和横向不稳定波长与韦伯数、动量比以及液相雷诺数有关，液膜破碎后的雾化粒径随着气流速度的增大而减小，与液膜破碎过程的破碎距离和横向不稳定波长呈线性关系。

Abstract:

High-speed camera， Planar Laser Induced Fluorescence （PLIF） and Phase Doppler Particle Analyzer （PDPA） were used to evaluate the break-up and atomization process of planar prefilm to evaluate the breaking-up and atomization characteristics of liquid prefilm. The result shows， liquid sheet on the prefilm plate can be divided into three shapes decided by air and liquid velocity ratio： smooth film surface （λ≤23）， wave film surface （23<λ<70） and film stripping （λ≥70）. Prefilm will break up into shapes of lobe， corrugation， hole， and ligament based on the effect of air and liquid velocity. The break-up length and transverse unstable wavelength of the prefilm break-up are dependent on Weber number， momentum ratio and liquid Reynolds number. The droplet size decreases with the increase of air velocity and is in a linear relationship with break-up length and transverse unstable wavelength.