为探究不同反压条件下缩进比和气液动量通量比对气液同轴离心式喷嘴自激振荡特性的影响，采用过滤水和干燥空气作为模拟介质在反压罐内进行试验，通过背景光成像技术获得了喷嘴不同结构和工况参数下的喷雾图像，同时对比分析了自激振荡喷雾和稳态喷雾的动态特性。结果表明：气液动量通量比不变时，低反压、低缩进比工况，喷雾更容易出现自激振荡。缩进比和反压增加均会抑制自激振荡发生。高反压条件下，增加缩进比有利于提高喷雾稳定性，但与此同时喷雾锥角减小，喷雾分布变得不均匀。自激振荡发生时，随着反压增加，喷嘴锥角先增加后减小，且喷雾锥角与自激振荡强度正相关，自激振荡强度最强时喷雾锥角最大。稳态喷雾锥角受反压影响程度较小，但自激振荡喷雾明显受反压影响，液膜先振荡扩张，而后破碎成小液滴再向中心收缩，整个过程周向旋转运动较弱，主要表现为轴向振荡。

The effect of gas-liquid momentum flux ratio and recess ratio on the self-pulsation characteristics of gas-liquid swirl coaxial injectors under various backpressure is explored. Atomization experiments were carried out in a backpressure tank by using filtered water and dry air. The spray images for different structures and working condition parameters of the injector were obtained by background light imaging. The dynamic characteristics of the self-pulsation spray and steady spray were compared and analyzed. The results show that when the gas-liquid momentum flux ratio is constant， the spray is more prone to self-pulsation under the ocnditions of low backpressure and small recess ratio. Both recess ratio and backpressure can restrain the occurrence of self-pulsation. Under high backpressure， increasing the recess ratio is beneficial to improving spray stability， but at the same time， the spray cone angle decreases and the spray distribution becomes uneven. When self-pulsation occurs， the spray cone angle increases at first and then decreases with the increase of backpressure， and the spray cone angle is positively correlated with self-pulsation intensity. The spray cone angle is the largest when self-pulsation intensity is the strongest. The steady spray cone angle is less affected by backpressure， but self-pulsation spray is obviously influenced by backpressure. The liquid film first expands with oscillation， then breaks into small droplets and shrinks to the center of injector. The circumferential rotation motion of the self-pulsation process is weak， showing axial oscillation mainly.