Shuang Zhou

To address the challenge of uneven coating deposition during air-assisted robotic spraying on horn-shaped surfaces, a gas–liquid coupled numerical model was developed using the Euler–Euler multi-phase flow approach and subsequently validated through experimentation. Two dynamic spray trajectories—axial spraying and circumferential spraying—were designed to examine the influence of spraying strategy, horn angle (ranging from 45° to 135°), spray distance, and spraying speed on film-forming characteristics. The results demonstrate that the features of the horn alter the near-wall flow field due to wall confinement effects, leading to spray splitting and kinetic energy attenuation with pronounced anisotropy. Specifically, stronger geometric constraints are observed along the minor axis, while weaker constraints are noted along the major axis. Axial spraying requires approximately 60% less time than circumferential spraying and results in more uniform coatings, thereby establishing it as the preferred strategy. In axial spraying, film thickness increases steadily with horn angle, with a 147.7% increase from 45° to 135°. Circumferential spraying achieves the best uniformity at angles of 67.5° to 90° due to geometric and temporal influences. Film thickness decreases with spraying speed following a power-law relationship (h ∝ 1/v). Pearson correlation shows moderate links between film thickness and horn angle (r = 0.466), spraying speed (r = −0.347), and spray distance (r = −0.325), with an ideal spray distance of 190–210 mm. The study highlights the anisotropic effects of horn features on spray flow, offering quantitative insights for precise robotic spraying of complex surfaces.

To address the challenge of uneven coating deposition during air-assisted robotic spraying on horn-shaped surfaces, a gas–liquid coupled numerical model based on the Euler-Euler multiphase flow approach was developed and experimentally validated. Two dynamic spray trajectories (axial spraying and circumferential spraying) were designed to investigate the effects of spraying strategy, horn angle (45°–135°), spray distance, and spraying speed on film-forming characteristics. Results indicate that horn features alter the near-wall flow field through wall confinement effects, causing spray splitting and kinetic energy attenuation with significant anisotropy—stronger geometric constraints along the minor axis and weaker along the major axis. Axial spraying requires approximately 60% less time than circumferential spraying and yields more uniform coatings, making it the preferred strategy. During axial spraying, the central film thickness increases monotonically with horn angle (up to 147.7% over 45°–135°), while circumferential spraying achieves optimal uniformity at 67.5°–90° governed by competing geometric and temporal effects. The film thickness approximately follows a power-law decay with spraying speed (h ∝ 1/v). Pearson correlation analysis identifies horn angle as the primary variable controlling film thickness (r = 0.466), followed by spraying speed (r = −0.347) and spray distance (r = −0.325), with an optimal spray distance of 190–210 mm recommended. This study reveals the anisotropic regulation mechanism of horn features on the spray flow field and provides quantitative guidance for precise robotic spraying of complex-curved components.