Simulation Analysis on Flow Field of Paint Mist Recovery with Single Nozzle for Ship Outer Panel Spraying Robot

Abstract

In this paper, we design a kind of negative pressure vacuum recovery hood, arranged at the front of the spray gun nozzle by CFD simulation; this addresses the paint mist pollution problem of the robot spraying on the outer plate of the ship, and the nozzle is arranged at the center of the recovery hood. Three vacuum recovery hood schemes are designed as follows: Scheme A, a hemispherical recovery hood with a diameter of 1.2 m; Scheme B, with a diameter of 1.6 m; Scheme C, with a diameter of 2.0 m. The recovery vacuum suction holes of the three recovery hoods are arranged differently. Firstly, a mathematical model of the spraying jet for the case of 0.48 mm diameter nozzle was established, and the established nozzle jet flow field model was verified to be feasible through case simulation analysis and experimental comparison. Secondly, a detailed discussion and analysis of the simulation process was conducted focusing on Scheme A. During the simulation of Scheme A, it was found that: the air velocity at the inlet surface and the kinetic energy of the paint mist had a large impact on the simulation effect, so it is necessary to try to further improve the structure of the recovery hood. Finally, the further simulation analysis of Scheme B and Scheme C shows that Scheme C > Scheme B > Scheme A in terms of the paint mist recovery effect. It can be seen that the use of Scheme C as a shipyard robotic spray paint mist recovery shows better results, which provides a theoretical scheme for shipyards to achieve paint mist anti-fouling as soon as possible.

A Review of the Developments of the Characteristics and Mechanisms of Airless Spraying on Complex Surfaces

“…In addition, the simulation results based on the Euler-Lagrange approach show a larger dispersion angle in the short-axis direction compared to the spraying experiments. On the contrary, Li [89] and Yi et al [90,91], who are also from the same research group, considered it more suitable for modeling by the Euler-Lagrange approach, owing to the low volume fraction of the droplet phase. Moreover, this method can better conform to the particle-loaded flow model and better simulate the impingement behavior of paint droplets on the wall, which cannot be achieved by the Euler-Euler approach.…”

“…They also presented numerical studies on spray painting processes using different atomizers (including airless sprayers), which found that the impacting droplet characteristics of the atomizers show significant influences on the properties of the forming paint films [88]. Similarly, based on the Eulerian-Lagrange approach, Li [89] and Yi et al [90,91] modeled the airless spraying on large ship exterior panels, and investigated the effects of the spraying parameters and their liquid film thickness distribution. Selected simulation results are shown in Figure 6.…”

Optimization Design of a Recovery System for an Automatic Spray Robot and the Simulation of VOC Recovery

“…Eddy currents are prone to occur in the cavity, resulting in the accumulation of VOCs inside the recovery hood. The flow field of a spray gun integrated with a single-layer recovery hood was first discussed by Yi et al [34], and the flow field caused by vacuum recovery suction was also studied. The characteristics of the recovery hood were optimized to improve the efficiency of paint misting to 83.4%, meeting the engineering needs of paintmist recovery during spraying operations.…”

“…The flow field generated by vacuum recovery suction can not only recycle the overspray paint mist but also have a significant impact on the paint mist that should be deposited on the ship hull. In addition, the physical phenomenon of VOCs evaporation was not considered by Yi et al [34]. Although the aforementioned research studies have made a lot of conceptual improvements in the ship painting system with the recovery function, some functions of the prototype production are still unsatisfactory and need to be further improved.…”