横向气流中液体射流袋式破碎机理

Bag Breakup of Round Liquid Jets in Crossflow

关键词:  液体圆形射流  横向气流  袋式破碎  破碎机理  袋的触发  高速摄像仪

Key words:  Round liquid jet  Crossflows  Bag breakup  Breakup mechanism  The onset of bags  High-speed camera

摘要:

采用高速摄像仪对横向气流场中的液体圆形射流袋式破碎过程进行了实验研究。实验所用喷嘴孔径为1.0mm,实验工质采用水。We_a范围覆盖11~23,液/气动量通量比q覆盖11~95。实验中观察了袋的形成及破碎过程。实验发现,袋的触发长度lonset/d与无量纲数In(q/Re) 存在线性关系,而袋的触发时间则为常数；对袋式结构的进一步研究得出袋的破碎长度与液体射流速度无关,只与We数有关,且成线性关系,即破碎长度随着We数的增加线性减小。最后还给出了核心射流破碎位置与液/气动量通量比q的关系,无量纲化破碎位置横坐标为常数,而无量化破碎位置纵坐标随着In (q)线性增加。以上结果可以指导实际设计合理安排袋的触发、破碎点位置,改善雾化性能；在数值模拟上能帮助构建精确的初始雾化模型,提高模拟精度。

Abstract:

An experiment was conducted to investigate bag breakup process of round liquid jets in crossflow. High-speed camera was used to observe the formation and breakup of bags. The diameter of the nozzle used in the experiment was 1.0 mm. And the test liquid was tap water. We number covered the range of 11~23, and liquid-to-air momentum flux ratio varied from 11 to 95. Present results indicate that the dimensionless onset length of bags (lonset/d) is linear to In(q/Re), while the dimensionless onset time is almost a constant. With We increasing, the bag breakup length decreased linearly, and was unrelated to liquid jet velocity. Finally the relationship between jet breakup point and liquid-to-air momentum ratio was studied, and it was found that the breakup position in the stream direction was always the same while the distance in the crossflow direction was increased with In(q) linearly.