# Impacts of Micro-Deviations of Aperture on the Characteristics of Collision Atomization Field
## 1 Introduction
Due to the effect of liquid surface tension, the fracture zone will gradually converge to form a liquid filament, which will break and produce large droplets. Under the synthetical influence of surface tension, density, viscous force and ambient air flow, large droplets proceed to break. When the droplet adapts itself to dynamic equilibrium with the surrounding airflow field, the eventual atomized droplet is generated [11]. Since the jet impingement atomizer has the advantages of uncomplicated structure, marvelous atomization and mixing performance, researchers have carried out extensive and in-depth research since [PERSON] observed two identical coaxial jets in 1833, and the liquid membrane generated by the collision broke into droplets [12]. Droplet size, atomization angle and flow coefficient are the most prominent parameters that an abundant amount of researchers are interested in. Based on the current research, the effects of liquid membrane breakage characteristics, atomization droplet formation process, spray conditions and nozzle structural parameters on the spray characteristics of impinging nozzles have been investigate extensively [13; 14; 15; 16; 17]. [PERSON] et al. [11] and [PERSON] et al. [18] employed numerical simulation to capture the liquid membrane formed after impact and inspect the impingement atomization growth of two jets, summarizing that the rupture process of the liquid membrane is mainly affected by liquid viscosity and surface tension. [PERSON] et al. [19] have inquired the atomization process of incompressible multiphase flow of diesel under low pressure injection by adaptive octree grid and VOF which involves a complex physical process and gas-liquid interaction. [PERSON] et al. [20] studied the breakup and atomization process of two impinging jets with non-Newtonian fluid as working fluid and found that with the increase in jet pressure, the shape of the liquid membrane formed after the impact of the gel propellant simulation material is transformed from the edge closed state to the edge opening state. [PERSON] et al. [21] and [PERSON] et al. [22] studied the atomization characteristics of different working fluids and found that the development process of spray can be divided into four parts: the complete conical liquid membrane stage, the liquid membrane and liquid zone coexistence stage, the turbulent reticulated liquid zone stage and the liquid zone and droplet coexistence stage, and the size of the liquid membrane increases with the increase in the jet velocity when the working mediums are water and the gel material. [PERSON] et al. [23] mainly researched the effects of nozzle geometry and Weber number on the characteristics of liquid membrane and droplet. The decisions demonstrate that the breakup mode of the liquid membrane is determined by Weber number and nozzle length. The increase in the Weber number promotes the breakup of liquid tape into liquid filaments and droplets. [PERSON] et al. [24] studied the effects of impingement parameters, geometry parameters and fluid viscosity on atomization performance and found that with the increase in injection pressure, the velocity of the droplet increases in all directions, the SMD (Sauter Mean Diameter) of the droplet decreases and the dimensionless average size SMD/D (D is Droplet diameter) of the droplet tends to be a constant value of 0.14. Nowadays, the research has gradually been enriched by simulation and experiment; however, there still exists indispensable research that requires enriching. From the brief review, it indicates that the diversity of the nozzle structure parameters, injection conditions and collision angle which may affect the atomization performance of the colliding atomizer has been investigated. Nonetheless, owing to the complexity of fluid dynamics, the miniaturization of nozzles and the lack of high-precision measurement and processing approaches, the analysis of the influence of machining errors on the atomization field is still in the primary stage.