Initial droplet conditions in numerical spray painting by electrostatic rotary bell sprayers / Nico Guettler in JOURNAL OF COATINGS TECHNOLOGY AND RESEARCH, Vol. 17, N° 5 (09/2020)  

[article]  inJOURNAL OF COATINGS TECHNOLOGY AND RESEARCH > Vol. 17, N° 5 (09/2020) . - p. 1091–1104 Titre : Initial droplet conditions in numerical spray painting by electrostatic rotary bell sprayers Type de document : texte imprimé Auteurs : Nico Guettler, Auteur ; Philipp Knee, Auteur ; Qiaoyan Ye, Auteur ; Oliver Tiedje, Auteur Année de publication : 2020 Article en page(s) : p. 1091–1104 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Atomiseurs Evaluation Fluides, Dynamique des Peinture au pistolet Pulvérisation électrostatique Revêtements:Peinture Simulation par ordinateur Index. décimale : 667.9 Revêtements et enduits Résumé : In computational fluid dynamics, the modeling of paint application processes by electrostatic rotary bell sprayer is mostly performed using an Euler–Lagrange approach. The initial conditions of the discrete phase—position, velocity, size, and charge—have an essential influence on the resulting film thickness distribution and the total charge transferred to the object. Typically, so-called injection models are used to specify these initial conditions, whereby the determination of the injection model coefficients is crucial. In this paper, a framework is proposed that combines experimental input data, an injection model, and a metamodel-based optimization. The painting tests for the generation of input and validation data were carried out in a technical center in the industrial standard. The simulations were performed using ANSYSFluent. Initial droplet conditions could efficiently be determined via the framework so that the painting-specific objectives were achieved with reasonable accuracy. In addition to the framework, a turbulence study of the strongly swirled shaping air of this atomizer was carried out, whereby a substantial underestimation of the axial air velocity was found in the turbulence models being investigated. The initial droplet conditions were also used in this study to draw conclusions about the accuracy of the airflow simulation. The proposed framework can be adapted to other solvers and efficiently finds injection model coefficients for other paint applicators. Note de contenu : - STRUCTURE AND OBJECTIVE OF THE FRAMEWORK - EXPERIMENTAL MATERIALS AND METHODS : Spray booth, atomizer, and paint material - Determination of shaping air velocity - Determination of particle size distribution - Determination of painting-specific data - NUMERICAL METHODS : Domain, grid and boundary settings - Turbulence model and solver settingst - Discrete phase model : motion of particles - SIMULATION OF THE AIRFLOW FIELD - MODELING INITIAL DROPLET CONDITIONS : Injection model : droplet position - Injection model : droplet velocity - Injection model : droplet size distribution - Injection : droplet charge - METAMODEL-BASED OPTIMIZATION OF INJECTION MODEL COEFFICIENTS : Design of experiments : sampling points - Conduction and evaluation of simulations - Principle component analysis - Training of metamodels - Multiobjective optimization DOI : https://doi.org/10.1007/s11998-020-00352-1 En ligne : https://link.springer.com/content/pdf/10.1007/s11998-020-00352-1.pdf Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=34552 [article]

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Primary breakup of a non-Newtonian liquid using a high-speed rotary bell atomizer for spray-painting processes / Bo Shen in JOURNAL OF COATINGS TECHNOLOGY AND RESEARCH, Vol. 16, N° 6 (11/2019)  

[article]  inJOURNAL OF COATINGS TECHNOLOGY AND RESEARCH > Vol. 16, N° 6 (11/2019) . - p. 1581-1596 Titre : Primary breakup of a non-Newtonian liquid using a high-speed rotary bell atomizer for spray-painting processes Type de document : texte imprimé Auteurs : Bo Shen, Auteur ; Qiaoyan Ye, Auteur ; Nico Guettler, Auteur ; Oliver Tiedje, Auteur ; Joachim Domnick, Auteur Année de publication : 2019 Article en page(s) : p. 1581-1596 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Atomiseurs Dépôt par pulvérisation Fluides non newtoniens Formation de film Revêtements:Peinture Rhéologie Simulation par ordinateur Système de pulvérisation (technologie) Index. décimale : 667.9 Revêtements et enduits Résumé : The present contribution deals with numerical and experimental studies of the primary liquid breakup process using a high-speed rotary bell atomizer. The first part of the investigations focuses on the film formation on the distributor disk and the inner surface of the rotary bell. Numerical simulations using the volume-of-fluid approach were carried out. A non-Newtonian liquid that has shear-thinning behavior is used to investigate the effect of the viscosity on the initial wetting, the film formation process, and the film thickness distribution on the bell. A nonhomogeneous film structure is found on the inner surface of the rotary bell. This is also observed in experimental investigations using a high-speed camera. The second part focuses on the disintegration process of the paint liquid in the near bell region. As inlet conditions for the breakup simulations, the properties of the liquid film at the bell edge, i.e., film thickness, velocities, and apparent viscosity, resulting from the film formation simulations were applied. Two different liquid disintegrations in the near-field were found, which were also observed in experimental investigations using a high-speed camera. Furthermore, user-defined functions were compiled in ANSYS Fluent to uniquely identify and characterize droplets formed through the breakup process. In this way, droplet properties such as diameter, velocity, and position can be determined. Note de contenu : - CHARACTERISTICS OF THE ATOMIZER : Experimental setup and measuring techniques - NUMERICAL METHODS - SIMULATION OF THE FILM FORMATION ON THE BELL : Computational domain - Wetting process on the bell - Simulation of air flow in the near bell region - Computational domain - Boundary conditions - Atomization regimes - Drop detection DOI : 10.1007/s11998-019-00231-4 En ligne : https://link.springer.com/content/pdf/10.1007%2Fs11998-019-00231-4.pdf Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=33411 [article]

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