气液两相环状流射流液膜的破碎与雾化特性实验研究

Experimental Study on Liquid Film Breakup and Atomization of Gas-Liquid Annular Flow Jet

关键词:  环状流射流  破碎模式  周期性  两段式破碎  液滴

Key words:  Annular flow jet  Breakup mode  Periodicity  Two-section breakup mode  Droplets

摘要:

采用可视化测试技术，针对气液两相环状流射流液膜的变形、破碎与雾化特性开展了实验研究。研究发现，自由发展环状流射流液膜的破碎过程具有周期性和不连续性特征；不同环状流流动条件下，射流液膜在宏观上存在三种不同的破碎模式：爆式破碎、两段式破碎和环膜袋式破碎。基于测试结果，给出了不同破碎模式对应的临界动力学条件；获得了两段式破碎模式下环状流气液动量通量比对射流液膜的破碎高度影响规律并建立了无量纲预测关联式，同时分析了不同位置处射流液膜的破碎特性以及雾化液滴粒径分布规律，发现增大射流气液动量通量比，后段液膜破碎产生的液丝液滴和前段液膜破碎形成的节点液滴粒径均减小，射流雾化效果变好。

Abstract:

In the present work， the characteristics of the deformation， breakup and atomization of the liquid film of gas-liquid annular flow jet were experimentally investigated by using visualization technique. It is found that the breakup of the liquid film of the annular flow jet has the features of periodicity and discontinuity. The results also show that there exist three breakup modes for the annular liquid film under different flow conditions， namely the burst breakup mode， the two-section breakup mode and the annular bag breakup mode. The critical dynamic conditions for different breakup modes are clarified based on the experimental results. In the case of the two-section mode， the effects of the gas-to-liquid momentum flux ratio of the annular flow on the breakup lengths for both the forepart and the rear part of the jet liquid film are obtained and the dimensionless correlations for them are developed. Moreover， the breakup features of the liquid films in both parts of the jet and the size distribution of the atomized droplets are discussed. It is shown that as the gas-to-liquid momentum flux ratio of the annular flow jet increases， both the droplets coming from the liquid filaments produced by the breakup of the rear part liquid film and the node droplets generated from the forepart liquid film all become smaller， and the atomization performance of the jet become better.