The oscillation of the mass flow rate of the input propellant in liquid rocket engines may induce a periodic heat energy release within the combustion chamber, resulting in operational instability. Since propellant components are discharged from the injector head, the injectors can play a role as a source of oscillation in the dynamic system of a liquid rocket engine. Prior studies confirmed that if the liquid spray and gas flow intersect by using gas-centered dual-swirl injector with tangential inlet in the gas flow path, droplets are generated with periodicity (fracture frequency). In this study, the characteristics and mechanisms of this periodicity were analyzed using longitudinal cross-section spray images. Since the multiple scattering signal that inhibits clarity is non-modulated components, it can be removed by using two modulated images with a phase difference of 180 deg (two-phase structured laser illumination planar imaging technique). And the dynamic characteristics of the gas–liquid spray were analyzed by applying the fast Fourier transform method. It was confirmed by this method that the fracture frequency was related to the impinging velocity of gas and hydrodynamic feature of liquid film. That is, it can be said that fracture frequency of the liquid film is dependent on the liquid Weber number and gas Weber number as the entrainment effect and impact force by gas flow are applied to the liquid film.

液体火箭发动机中输入推进剂的质量流量的波动可能会导致燃烧室内周期性的热能释放，导致运行不稳定。由于推进剂成分从喷油器头排出，喷油器在液体火箭发动机的动力系统中可以起到振动源的作用。先前的研究证实，如果在气流路径中使用带切向入口的气心双旋流喷射器使液体喷雾和气流相交，则会产生周期性（破裂频率）的液滴。在这项研究中，使用纵向截面喷雾图像分析了这种周期性的特征和机制。由于抑制清晰度的多重散射信号是非调制分量，它可以通过使用两个相位差为 180 度的调制图像（两相结构激光照明平面成像技术）来消除。并应用快速傅里叶变换方法分析了气液喷雾的动态特性。该方法证实了破裂频率与气体的撞击速度和液膜的流体动力学特征有关。即，可以说液膜的破裂频率取决于液体韦伯数和气体韦伯数，因为气流的夹带效应和冲击力施加到液膜上。该方法证实了破裂频率与气体的撞击速度和液膜的流体动力学特征有关。即，可以说液膜的破裂频率取决于液体韦伯数和气体韦伯数，因为气流的夹带效应和冲击力施加到液膜上。该方法证实了破裂频率与气体的撞击速度和液膜的流体动力学特征有关。即，可以说液膜的破裂频率取决于液体韦伯数和气体韦伯数，因为气流的夹带效应和冲击力施加到液膜上。