Modeling of Film Formation in Airless Spray

Self Cite

The special surface appearance of complex surfaces restricts the coating film quality of spraying. The study of the atomization and film formation characteristics of typical complex surfaces, as well as the spraying mechanism, is essential for planning the spraying robotic trajectory and improving the spraying efficiency. In this paper, modeling and characteristics of the atomization and film formation process, based on CFD numerical simulations in previous studies, are systematically reviewed, focusing especially on airless spraying. In addition, the advantages and disadvantages of the existing research from the perspective of numerical models and methods are discussed. Finally, a further research direction for spraying on complex surface is prospected. Overall, a comprehensive and up-to-date review of spray atomization and film formation characteristics is considered valuable to practitioners and researchers in these fields, and will facilitate the further application of robotic spraying in the mechanical, automotive, marine, aerospace, petrochemical and other industries.

Section: Discussion On Multiphase Flow Modelsmentioning

confidence: 99%

“…For model comparison, airless spraying film formation characteristics based on the Euler-Euler approach and the Euler-Lagrange approach, respectively, investigated by the same research group are listed here [114,122], as is shown in Figure 8. With the same number of meshes and parameter settings, the model based on the Euler-Euler approach only took half the time of the other, and achieved the same level of solution accuracy.…”

Section: Discussion On Numerical Models For Airless Spraying Simulati...mentioning

confidence: 99%

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

Wu,

Chen,

Liu

et al. 2023

Self Cite

“…The droplet trajectories were modeled using a discrete phase model in the Fluent code. The thickness of the coating film was simulated using the Euler-Lagrange method with a Rosin-Rammbler atomization model in an airless spraying process [16]. The effect of the mixer blade orientations on the spray-wall interaction was simulated using the Euler-Lagrange method in a channel [17].…”

Section: Introductionmentioning

confidence: 99%

A CFD-DEM Simulation of Droplets in an Airless Spray Coating Process of a Square Duct

Li,

Chen,

Hong

et al. 2024

The purpose of this paper is to provide a numerical simulation, taking into account the collisional interactions of droplets in an airless rotary spray coating process. The hydrodynamics of gas and droplets are simulated using the CFD-discrete element method (DEM) with the JKR contact model in an airless rotary spray coating process of a horizontal square duct. The surface energy parameter used in the JKR model is calibrated using a virtual accumulation angle test in the funnel device. Based on the distribution of accumulation angles, a suitable surface energy for wall droplets is proposed. A rational gas RNG k-ε model is suggested in accordance with the comparisons of velocities, standard deviations, and the skewness of droplet number fractions from three turbulence models. The simulations of droplet film thicknesses agree with measurements from the literature regarding the film thickness along a vertical panel. The correlations of the exit gas and droplet velocities of sprayer holes are proposed with a discharge coefficient of 0.85 for gas and 5.87 for droplets. A number index of droplets is introduced in order to measure the uniformity of droplet distributions. A low droplet number index is found at low rotational speeds, representing a more uniform distribution of droplets as the rotation speeds reduce within the square duct. The normal force between the droplet and the wall is approximately an order of magnitude larger than the droplet–wall tangential force of collisions.

“…Through the two-way coupling method, researchers considered the interaction between the two phases in the modeling [12][13][14][15]. Yang et al [16] proposed a coating film-forming model based on the Euler-Lagrangian method and established a Rosin-Rammler atomization model. Zhou et al [17] applied a coupling algorithm between Volume of Fluid and Lagrangian Particle Tracking (VOF-LPT) for spraying simulations.…”

Section: Introductionmentioning

confidence: 99%

Modeling and Characteristics of Airless Spray Film Formation

Yang

Chen

et al. 2022

Self Cite

Based on the computational fluid dynamics (CFD) theory, this paper proposes a film formation model and a numerical simulation method that can be used in thickness prediction of airless spraying robots. The spraying flow field and the film formation process in the airless spraying process were simulated by the Eulerian–Eulerian approach, and the airless spraying film formation model including the paint expansion model and the wall hitting model was established. To verify the correctness of the model, numerical simulations of static spraying and dynamic spraying were carried out on the plane and arc surfaces. The simulation results showed that the width of the spraying flow field on the far wall increased linearly with the longitudinal distance in the major-axis direction. The busbar spraying on the outer surface of the arc surface showed the similar characteristics to the plane in the major-axis direction. Besides, the annular spraying was similar to the plane spraying in the minor-axis direction, but the inner surface spraying was completely opposite. When spraying the outer surface, the film thickness increased with the increase of the inner diameter but was smaller than that of the plane spraying, while the inner surface spraying was completely opposite. In the spraying experiment, the plane dynamic spraying and the arc plane inner and outer surface translation spraying were selected for verification. The experimental results were in good agreement with the simulation results, indicating that the film formation model of airless spraying established in this paper is basically correct. As a result, this model can be used for thickness prediction of spraying robots.