Modeling and Numerical Investigation of Air Spraying Film Formation on Arc-Shaped Bent Pipe

Taking arc-shaped bent pipes as the subject of study, a three-dimensional dynamic spraying numerical model based on Euler–Euler approach and a wall film formation model was developed through numerical simulation and experimental validation. The effects of geometric parameters, such as the bending radius and pipe diameter, on the distribution of coating thickness were systematically investigated. Numerical simulations were used to reproduce the motion of gas–liquid two-phase flow and the evolution of spray film formation, and the reliability of the model was verified experimentally. The results indicate that the film thickness distribution for axial spraying exhibits good stability, whereas circumferential spraying shows significant position dependence due to differences in local curvature and the angle of incidence. In addition, increased curvature in convex areas reduces the peak film thickness and widens the spray pattern, while concave areas enhance localized deposition, resulting in a narrower distribution of the coating. Spray coating experiments conducted on flat and bent pipe confirmed that the film thickness distribution trends and peak locations predicted by the model were in good agreement with the experimental results. This study provides a theoretical basis and practical guidance for spray trajectory planning and film thickness control in complex curved components.