10.24423/EngTrans.3075.20230418
Numerical Estimation of Film Thickness With an Air-Assisted Spray Gun
The main goal of this study is to present the effects of spraying parameters on the numerical evaluations of the fundamental behaviors of an air-assisted spray gun during the formation of child droplets in the spray flow field and material deposition on the target surface. For this purpose, first of all, the air-assisted spray gun geometry was created using the Solidworks software. Then, a computational domain with a 3D, unstructured grid structure was generated using the ANSYS-Workbench meshing tool. Numerical calculations were conducted using ANSYS-Fluent 2020-R2 commercial software. Different breakup models and their effects on the child droplet size were investigated. By coupling the Taylor analogy breakup (TAB) model and discrete phase model (DPM), the droplet size, trajectory, and coating thickness calculations were made under different atomizing air pressures. Also, the effects of spraying distance and droplet size on coating thickness and the critical Weber (We) number on the atomized particle diameter and particle speed were investigated. The results show that with the increase in atomizing air pressure, droplet sizes decrease and the film thickness on the center of the target surface and droplet speeds increases. Also, increasing the critical Weber number makes it more difficult to atomize the droplets.
Copyright © The Author(s). This is an open-access article distributed under the terms of the Creative Commons Attribution-ShareAlike 4.0 International (CC BY-SA 4.0).
References
Antonio J.K., Optimal trajectory planning for spray coating, Proceedings of the IEEE International Conference on Robotics and Automation, vol. 3, pp. 2570–2577, 1994, doi: 10.1109/robot.1994.351125.
Ye Q., Domnick J., Analysis of droplet impingement of different atomizers used in spray coating processes, Journal of Coatings Technology and Research, 14(2): 467–476, 2017, doi: 10.1007/s11998-016-9867-4.
Liao Y., Sakman A.T., Jeng S.M., Jog M.A., Benjamin M., A comprehensive model to predict simplex atomizer performance, Proceedings of the ASME 1998 International Gas Turbine and Aeroengine Congress and Exhibition. Volume 3: Coal, Biomass and Alternative Fuels; Combustion and Fuels; Oil and Gas Applications; Cycle Innovations, Stockholm, Sweden. June 2–5, 1998, doi: 10.1115/98-gt-441.
Ansdell D.A., Automotive paints, [in:] Paint and Surface Coatings: Theory and Practice, R. Lamboune, T.A. Strivens [Eds.] , pp. 431–489, John Wiley & Sons, New York, NY, 1987.
Chen H., Xi N., Sheng W., Dahl J., Optimizing material distribution for tool trajectory generation in surface manufacturing, Proceedings of the 2005 IEEE/ASME International Conference on Advanced Intelligent Mechatronics, Monterey, CA, USA, pp. 1389–1394, 2005, doi: 10.1109/AIM.2005.1511205.
Kim D., Yoon Y., Hwang S., Lee G., Park J., Visualizing spray paint deposition in VR training, Proceedings of 2007 IEEE Virtual Reality Conference, Charlotte, NC, USA, pp. 307–308, 2007, doi: 10.1109/VR.2007.352515.
Luangkularb S., Prombanpong S., Tangwarodomnukun V, Material consumption and dry film thickness in spray coating process, Procedia CIRP, 17: 789–794, 2014, doi: 10.1016/j.procir.2014.02.046.
Fogliati M., Fontana D., Garbero M., Vanni M., Baldi G., Dondè R., CFD simulation of paint deposition in an air spray process, JCT Research, 3(2): 117–125, 2006, doi: 10.1007/s11998-006-0014-5.
Ye Q., Domnick J., Khalifa E., Simulation of the spray coating process using a pneumatic atomizer, ILLAS-EUROPE 2002, 18th Annual Conference on Liquid Atomization & Spray Systems, Zaragoza, SPAIN, September, 9–11, 2002. Zaragoza, 9(11), 2002.
Ye Q., Shen B., Tiedje O., Bauernhansl T., Domnick J., Numerical and experimental study of spray coating using air-assisted high-pressure atomizers, Atomization and Sprays, 25(8): 643–656, 2015, doi: 10.1615/AtomizSpr.2015010791.
Xie X., Wang Y., Research on distribution properties of coating film thickness from air spraying gun-based on numerical simulation, Coatings, 9(11): 721, 2019, doi: 10.3390/coatings9110721.
Wang Y.-A., Xie X. -P., Lu X.-H., Design of a double-nozzle air spray gun and numerical research in the interference spray flow field, Coatings, 10(5): 475, 2020, doi: 10.3390/coatings10050475.
Hiltunen K. et al., Multiphase Flow Dynamics, Theory and Numerics, VTT Publications 722, 2009.
Ishii M., Thermo-fluid dynamic theory of two-phase flow, NASA STI/Recon Technical Report A, 75: 29657, 1975.
O’Rourke P.J., Amsden A., The TAB method for numerical calculation of spray droplet breakup, SAE Technical Paper, No. 872089, 1987, doi: 10.4271/872089.
Lamb H., Hydrodynamics, 6th ed., Dover Publications, New York, 1945.
Beale J.C., Reitz R.D., Modeling spray atomization with the Kelvin-Helmholtz/Rayleigh-Taylor hybrid model, Atomization and Sprays, 9(6): 623–650, 1999, doi: 10.1615/AtomizSpr.v9.i6.40.
ANSYS Fluent Theory Guide, Ansys Inc., USA, 15317, pp. 724–746, 2020.
Apte S.V., Gorokhovski M., Moin P., LES of atomizing spray with stochastic modeling of secondary breakup, International Journal of Multiphase Flow, 29(9): 1503–1522, 2003, doi: 10.1016/S0301-9322(03)00111-3.
Yi Z., Mi S., Tong T., Li K., Feng B., Li B., Lin Y., Simulation analysis on the jet flow field of a single nozzle spraying for a large ship outer panel coating robot, Coatings, 12(3): 369, 2022, doi: 10.3390/coatings12030369.
Li W., Qian L., Song S., Zhong X., Numerical study on the influence of shaping air holes on atomization performance in pneumatic atomizers, Coatings, 9(7): 410, 2019, doi: 10.3390/coatings9070410.
Barth N., Schilde C., Kwade A., Influence of particle size distribution on micromechanical properties of thin nanoparticulate coatings, Physics Procedia, 40: 9–18, 2013, doi: 10.1016/j.phpro.2012.12.002.
Liu Y., Zeng Y., Zhao X., Liu J., Liu D., Analysis of film forming law and characteristics for an air static spray with a variable position of the plane, Coatings, 11(10): 1236, 2021, doi: 10.3390/coatings11101236.
Li C. -J., Li W. -Y., Wang Y. -Y., Yang G. -J., Fukanuma H., A theoretical model for prediction of deposition efficiency in cold spraying, Thin Solid Films, 489(1–2): 79–85, 2005, doi: 10.1016/j.tsf.2005.05.002.
DOI: 10.24423/EngTrans.3075.20230418