# 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  
Figure 10 shows the atomization field structure of three equal diameter nozzles (the diameter of each pair of colliding nozzles remains equal) \(N_{1}\), \(N_{6}\) and \(N_{11}\) at the collision angle of 60\({}^{\circ}\) under different input pressures. It can be found that no matter what kind of inner diameter of the nozzle, when the injection pressure increases, accompanied by the breakup of the liquid membrane, the collision between the two jets will become more intense. When the pressure reaches a certain value, the atomization field will almost maintain a steady state, and the parameters of the atomization field will tend to be stable. When the jet pressure is small, the liquid membrane has a relatively complete and regular edge, and the size of the liquid membrane increases with the Weber number. For \(N_{1}\), \(N_{6}\) and \(N_{11}\), when the injection pressure is 0.30 MPa, 0.35 MPa and 0.32 MPa, respectively, the edge of the corresponding liquid membrane begins to break, becoming no longer continuous and regular, and obvious surface waves appear on the surface of the liquid membrane. This is because the liquid membrane is disturbed by the external air at the gas-liquid interface and forms waves on its surface, which is also called air disturbance wave. The bottom liquid membrane appears to peel and then gradually breaks up to form droplets. From the change in the atomization field shown in Figure 10, we can see that with the increase in injection pressure, the liquid membrane formed at the bottom of the liquid membrane shrinks and the spray angle continues to increase. In Figure 10a-c, when the jet pressure reaches 0.84 MPa, 0.87 MPa and 0.85 MPa, respectively, it is difficult to see the edge of the liquid membrane formed by jet collision, which is called boundless mode. With the increase in the Weber number, the position of the liquid membrane breaking is closer to the impact point of the jet, which indicates that the air disturbance wave increases with the increase in the Weber number. In the boundless mode, during the downward movement of the periodic bow-shaped liquid filament, a large number of droplets appear due to continuous breaking. Figure 9: The cavitation state of the flow field in the 1 mm orifice when the aspect ratio is 4 in the experiment. (**a**) 0.2 MPa. (**b**) 0.3 MPa. (**c**) 0.35 MPa. (**d**) 0.4 MPa. (**e**) 0.8 MPa. The diameter directly affects the orifice flow, while the injection pressure controls the growth rate and trend of volume flow. Figure 11 shows the relationship between volume flow rate and injection pressure in single nozzles with small deviation. Taking \(N_{6}\) (1.00 mm) as the standard diameter, the critical pressure required to induce cavitation and hydraulic turnover will be reduced by approximately 2.1% and 2% when the diameter is reduced by 2%, and will be further reduced to 5.3% and 6.3% when the diameter is reduced by 4%. Similarly, when the diameter increases by 2%, the critical values of the initial cavitation and hydraulic turnover increase by approximately 2.6% and 2.5%, and when the diameter increases by 4%, the critical values will further increase to 4.7% and 5%. Figure 11: Relationship between the volume flow rate and injection pressure of single small deviation cylindrical nozzles. Figure 10: The atomization field structure images of \(N_{1}\), \(N_{6}\) and \(N_{11}\) nozzles under different input pressures at 60\({}^{\circ}\) collision angle. (**a**) \(N_{1}\). (**b**) \(N_{6}\). (**c**) \(N_{11}\). In addition, it can be seen from Figure 11 that for a nozzle with a specific diameter, the volume flow rate increases with the increase in injection pressure. However, when cavitation occurs, the flow channel narrows and the volume flow rate decreases sharply until the hydraulic overturning phenomenon is completed, and the volume flow rate begins to increase again, but the growth rate slows down.