离心甩油盘径向喷雾破碎机理实验研究

Experiment on Spray Breakup Mechanism of a Rotary Atomizer with Radial Discharge Channel

关键词:  甩油盘雾化  高速阴影成像  破碎模式  雾化粒径  离散度

Key words:  Rotary atomizer  High-speed shadow imaging  Breakup mode  Droplet size  Dispersion

摘要:

本文发展了离心甩油盘高速旋转雾化的光学测试实验台，采用高速数字成像、高速阴影成像等可视化方法研究了在不同转速（8~20kr/min）和燃油流量（4~15g/s）下航空煤油的喷雾形态及燃油破碎过程，分析了喷雾特性变化规律，并采用激光粒度分析仪测量了不同工况下的燃油雾化粒径及其分布规律。实验结果表明，甩油盘雾化过程中，科氏力推动液膜聚积在与甩油盘旋转方向相反的喷口一侧，且甩油盘喷孔出口处的液体呈薄片状。随着燃油的进一步破碎雾化，实验中观察到三种不同的破碎形态：韧带破碎、袋状破碎和剪切破碎，跟转速和燃油流量有关，研究基于气动韦伯数和液气动量比给出了破碎模式图。研究表明甩油盘转速是影响雾化特性的主要因素，甩油盘转速越高，燃油粒径越小；离散度在气动韦伯数和液气动量比的综合作用下呈现不同的变化趋势。

Abstract:

A high-speed rotary spray optical test bench was developed for rotary atomizer study. Spray morphology as well as fuel breakup process of aviation kerosene were measured by high-speed digital imaging and high-speed shadow imaging technique under different rotational speeds （8~20kr/min） and liquid flow rates （4~15g/s）， respectively. The variation of spray characteristics is analyzed， and laser particle size analyzer was used for recording the particle size of the fuel droplet as well as the droplet size distribution. The experimental results show that Coriolis force pushes the liquid film to the side of the channel exit opposing the rotational direction. The liquid stream issues from the atomizer orifice exit as a thin liquid sheet. As the liquid film breaks up further， three breakup modes such as ligament， bag， and shear breakup were observed. Moreover， these modes vary with the rotational speed and liquid flow rates. A breakup mode map is presented based on aerodynamic Weber number and the liquid to air momentum flux ratio. The results indicate that rotational speed of the rotary atomizer is a main factor influencing spray characteristics. Sauter mean diameter decrease with the increasing of the rotational speed. Dispersion has different trend with the coaction of dynamic Weber number and liquid to air momentum flux ratio.