Numerical Study on the Influence of Shaping Air Holes on Atomization Performance in Pneumatic Atomizers

In pneumatic atomizers, the shaping air holes play an important role in the spraying system. The pressure and intersection of shaping air holes are the two most important parameters in engineering. In this paper, the Euler–Lagrangian method is used to describe the two-phase spray flow. The spraying process of the pneumatic nozzle is simulated numerically, and the experiment is designed to verify this simulation. By setting different air pressures and distances between the intersection and the paint hole, target surface pressure and droplet size distribution are investigated in detail, in order to explore the relationship between shaping air holes in pneumatic nozzles and overspray. From the results of the numerical simulation, it is found that an increase in the distance between the intersection and the paint hole increases the gas velocity at the central axis of the nozzle and the central pressure of the target surface, the droplet size becomes larger, and the distribution of droplets is more concentrated on the target surface, which easily leads to overspray. With the increase in the pressure of the shaping air holes, the central pressure of the target surface decreases, and the ovality of the spraying pattern on the target surface increases.