横向气流中液体圆柱射流的破碎特性和表面波现象

采用高速摄像仪对横向气流场中的圆形液体射流的圆柱破碎过程(低Weber数)进行了实验研究.实验采用直射式喷嘴,喷孔直径为0.3mm和0.5mm,喷嘴长径比均为40.实验工质采用水.Weber数为1.7~7,液/气动量通量比为3.4~83.实验观察了表面波现象及射流破碎形成的液滴的尺寸及其速度.观测发现,表面波波长随着气流Weber数的对数的增加而线性减小.破碎后形成的液滴直径 d_p/d₀与Weber数的对数成正比.液滴的初始x方向速度与y方向速度大小与液滴直径无关.在实验范围内,液滴y方向速度均不随Weber数和液/气动量通量比的变化,约为初始射流速度的0.94倍;而液滴x方向速度约为0.085倍的气流速度.对表面波和破碎后形成的液滴尺寸及速度的研究有助于构建更精确的初始雾化模型. 

Breakup characteristics and surface wave phenomenon of round liquid jets in crossflows

An experiment was conducted to investigate column breakup process of round liquid jets in crossflow.High-speed camera was employed to observe surface wave phenomenon and the formation of droplets.The injectors used in the experiment were plain orifice nozzle and their diameters were 0.3mm and 0.5mm.The test liquid was tap water.Test Weber number covered the range of 1.7~7,and liquid-to-air momentum flux ratio varied from 3.4 to 83.Present results indicate that the surface wavelength,is in negative proportion to the logarithm of Weber number.With the increase of the logarithm of Weber number,the diameters of droplets increase linearly.Droplets' velocities,both streamwise direction and cross stream direction,are independent on their diameters.In the range of the experiment,droplets' cross stream velocity equals to about 0.94 v_j,and droplets' streamwise velocity is about 0.085 u_a.The results of surface wavelength and droplet's diameter and velocity can significantly improve the accuracy of primary breakup model.