双股射流碰撞雾化特征实验

为改善双股射流碰撞雾化器的雾化性能,基于自行搭建的射流碰撞雾化实验台,采用CCD拍摄技术,研究射流速度、碰撞角度、喷嘴出口内径和黏度对雾化特征的影响.结果表明:随着射流韦伯数和碰撞角度的增大,喷雾角增大,液滴的索太尔平均直径(SMD)减小,且液滴分布更加均匀;喷嘴内径较小时形成的液膜厚度较薄,稳定性差,喷雾角较小,在所研究的范围内,液滴的平均直径不受喷嘴内径的影响;液体黏度越大,液膜越稳定不易破碎,液膜尺寸越大,喷雾角越小,液滴的平均粒径越大;在韦伯数较小时,差异明显,而在较高的韦伯数条件下,差距较小.在进行40%浓度甘油溶液雾化实验时,观察到了液膜翻转现象,从碰撞点往下出现连续多个相互垂直的液膜.因此,增大射流速度、碰撞角度,减小液体黏度,有助于改善雾化性能.

Atomization characteristics experiment of impinging jets

To improving the atomization characteristics of dual impinging jets, based on the impinging jets platform established by ourselves, the effects of jet velocity, impingement angle, nozzle diameter and liquid viscosity on the atomization characteristics were studied by CCD Photography technology. The experimental results indicate that with the increase of Weber number and impingement angle, the spray angle is increased, droplet SMD is decreased and the droplet distribution is more uniform. When the nozzle diameter is small, the thickness of liquid sheet is small, the liquid sheet is unstable and the spray angle is small. The nozzle diameter has little influence on SMD. Besides, the larger the liquid viscosity, the more unstable of the liquid, the larger the liquid size, the smaller the spray angle and the larger the droplet SMD. When the Weber number is small, the difference is obvious and when the Weber number is large, the difference is smaller. Also, in the study of 40% concentration of glycerol solution atomization characteristics, the phenomenon of liquid sheet flip was observed, and multiple consecutive perpendicular liquid sheets could appear down from the impact point. In conclusion, increasing the jet velocity and impinging angle and decreasing the liquid viscosity can improve the atomization characteristics.