横流作用下气液两相环状流射流液膜的雾化特性实验研究

Experimental Study on Liquid Film Atomization of Gas-Liquid Annular Flow Jet in Crossflow

关键词:  环状流射流  横流  破碎与雾化  破碎模式  液滴  高速摄像

Key words:  Annular flow jet  Crossflow  Breakup and atomization  Breakup mode  Droplet  High speed photography

摘要:

为了更好地认识横向气流对气液两相环状流射流雾化过程的影响，采用高速摄像等技术，针对气液两相环状流射流液膜在横向气流中的破碎与雾化特性开展了实验研究。研究发现，气液两相环状流射流在横流作用下能够实现稳定的雾化，射流液膜的破碎与雾化具有周期性和不连续性特征；查清了雾化过程中射流液膜存在三种不同的破碎模式：爆式破碎、分段式破碎和环膜破碎，并对每种破碎模式下的液膜破碎特征进行了研究；结合实验结果统计分析，获得了射流液膜不同破碎模式的动力学条件和变化规律；同时对环状流射流液膜不同破碎阶段的雾化液滴的粒径分布进行了统计分析，发现三种破碎模式下，液膜的爆式破碎产生的雾化液滴粒径更小，雾化效果较好，同时提高环状流表观气速和横流速度也能够促进射流液膜的雾化。

Abstract:

In order to better understand the effects of the crossflow on the atomization of the gas-liquid annular flow jet， the characteristics of the breakup and atomization of the liquid film of the gas-liquid annular flow jet in the crossflow were experimentally investigated by using high speed photography technology in the present work. It is found that the gas-liquid annular flow jet can realize stable atomization in the crossflow， and the breakup and atomization of the jet liquid film have the features of periodicity and discontinuity. Three distinct breakup modes for the annular flow jet liquid film are clarified， namely the burst breakup mode， the segmental breakup mode and the annular film breakup mode. The characteristics of the liquid film evolution of the jet for each breakup mode are studied. The flow dynamic conditions for different breakup modes of the jet liquid film are obtained based on experimental statistical analysis. Furthermore， the diameter distributions of the droplets that came from different breakup stages of the liquid film of the annular flow jets are statistically analyzed quantitatively and the results show that among the three breakup modes， the burst breakup of the jet liquid film will produce more smaller droplets and achieve the best atomization quality. In addition， the increase in the superficial gas velocity of the annular flow as well as the velocity of the crossflow can also improve the atomization performance of the annular flow jet liquid film.