# Impacts of Micro-Deviations of Aperture on the Characteristics of Collision Atomization Field
## 5 Results and Discussion
### Influence of Colliding Aperture Deviation on Atomization Effect
For collision nozzle \(N_{1}\), the maximum difference of SMD corresponding to four injection pressures is 5 \(\upmu\)m, while the difference is about 25 \(\upmu\)m when colliding with nozzle \(N_{11}\). In Figure 13b, SMD decreases with the increase in injection pressure. This is because the increase in injection pressure will lead to more obvious cavitation phenomenon in the internal flow field, which directly causes the increase in collision velocity. The impact  
Figure 13: The curves of SMD of atomized droplet with colliding aperture and injection pressure. (**a**) The relationship between SMD and the colliding aperture under different jet pressures. (**b**) The curve of SMD with injection pressure for the small range of collision aperture. strength of the two jets is greater, the atomization field is more fully atomized and the SMD is smaller. When the injection pressure is in the range of 0.20-1.00 MPa, the SMD range of \(N_{10}\) jet with colliding aperture is the largest, which is 22 \(\upmu\)m, and the SMD range of \(N_{2}\) jet with colliding aperture is the smallest, which is 8 \(\upmu\)m. When the diameter of the impinging nozzle changes uniformly about 1 mm, the SMD changes relatively evenly, and with the increase in injection pressure, it will eventually become a stable value. In a word, it can be seen from Figure 13 that the increase in the injection pressure and the decrease in the impinging orifice diameter will lead to higher jet velocity and smaller jet diameter, which will make the impact of the atomization field more intense, the atomization effect more sufficient and obtain smaller SMD. Figure 14 shows the variation curve of the atomization cone angle with colliding aperture and jet pressure. It can be seen from the figure that with the increase in injection pressure, the atomization cone angle corresponding to the same pair of nozzles increases, and the final atomization cone angle tends to be stable, and gradually approaches and does not exceed the collision angle of the two nozzles. When the injection pressure is 0.3 MPa, the difference in the atomization cone angle of five pairs of nozzles is the smallest, and then the difference increases gradually until the atomization field reaches the steady state. When the pressure is small, the atomization cone angle increases greatly. This is due to the sudden appearance of cavitation, which causes the jet to collide violently. At the same injection pressure, the atomization cone angle increases with the increase in the nozzle diameter. The atomization cone angle of \(N_{2}\) and \(N_{10}\) approaches 53\({}^{\circ}\) and 60\({}^{\circ}\), respectively. This is because the process of the liquid membrane breaking is disturbed by the surrounding air. When the inner diameter of the nozzle is small, the liquid membrane formed by the collision of two jets is relatively thin. At the same time, the research of [PERSON] [37] shows that the inner diameter of the nozzle has a weak influence on the waviness of the liquid membrane surface, and the waviness of the liquid membrane formed by the small inner diameter of the nozzle is denser. A slight disturbance can rupture the formed liquid membrane, and it is not easy to spread to both sides, so the final spray angle is small.