针对反压条件下雾化数据缺乏、雾化机制不清的问题，采用直流自击喷嘴，在反压雾化实验仓中开展了0.1~4.1 MPa环境条件下的雾化特性宏观及微观实验研究。基于高速阴影成像方法获得了不同反压下自击喷嘴的喷雾宏观形貌并提取出雾化角、雾化场液滴速度分布等数据，进一步通过相位多普勒粒子分析（PDPA）激光测量手段获得了不同反压下液滴直径概率密度分布及索特平均直径（SMD）等微观特性参数。实验结果表明，高反压会导致喷雾总体发展受到压缩，雾化角减小，且雾化液滴的数量密度更为稠密；液滴速度随着反压增大，衰减更为显著；但液滴SMD随反压增大呈现非单调演化规律，且演化规律与沿喷孔出口的竖直距离有关，即当反压小于1.1 MPa时，液滴SMD随反压的增大而减小，在H=20 mm处，当反压从1.1 MPa增大到3.1 MPa，SMD基本保持不变，而进一步增大反压时，SMD逐渐增大。在H=30 mm处，当反压大于1.1 MPa时，SMD逐渐增大。分析认为，反压增大导致更高的液滴数量密度，提升了液滴碰撞并聚合的概率，使高反压下液滴SMD增大。

Aiming at the lack of atomization data and unclear atomization mechanism under back pressure， we conducted both macro and micro experimental research on atomization characteristics under the back pressure of 0.1–4.1 MPa using an impinging jet injector. Based on the high-speed shadow imaging method， the spray macro-morphology of the impinging jet injector under back pressure was obtained， and the atomization angle， the spatial distribution of droplet velocity in the spray field and other data extracted. Furthermore， the microscopic parameters such as the probability density distribution of droplet size and the Sauter Mean Diameter （SMD） under back pressure were obtained by the Phase Doppler Particle Analysis （PDPA） laser measurement method. The experimental results show that high back pressure compresses the overall development of spray， reduces the atomization angle， and increases the number density of atomized droplets. With the increase of back pressure， the droplet velocity attenuates more significantly. However， the SMD of droplets shows a non-monotonic evolution law with the increase of back pressure， and the evolution law is related to the vertical distance along the nozzle outlet. At a back pressure smaller than 1.1 MPa， the SMD of droplets decreases with the increase of back pressure. At H=20 mm， when the back pressure increases from 1.1 MPa to 3.1 MPa， the SMD remains basically unchanged， while further increasing back pressure leads to gradual SMD increase. At H=30 mm， back pressure larger than 1.1 MPa results in gradual SMD increase. It is considered that the increase of back pressure leads to higher droplet number density and increases the probability of droplet collision and polymerization， explaining the increase of droplet SMD under high back pressure.