Flow stabilization and coating thickness reduction through use of multi-slot air-knife in gas jet wiping / J. R. McDermid ; Andrew N. Hrymak ; F. E. Goodwin in JOURNAL OF COATINGS TECHNOLOGY AND RESEARCH, Vol. 19, N° 1 (01/2022)  

[article]  inJOURNAL OF COATINGS TECHNOLOGY AND RESEARCH > Vol. 19, N° 1 (01/2022) . - p. 143-158 Titre : Flow stabilization and coating thickness reduction through use of multi-slot air-knife in gas jet wiping Type de document : texte imprimé Auteurs : J. R. McDermid, Auteur ; Andrew N. Hrymak, Auteur ; F. E. Goodwin, Auteur Année de publication : 2022 Article en page(s) : p. 143-158 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Fluides, Mécanique des Galvanisation Matériaux -- Epaisseur Revêtements Tags : 'Balayage  au  jet  de  gaz'  'Réduction  l'épaisseur  du  revêtement'  'Lame  d'air  multi-fentes'  'Galvanisation  à  chaud  continue'  'Modélisation  des  turbulences'  'Mesures  d'épaisseur Index. décimale : 667.9 Revêtements et enduits Résumé : This paper investigates the gas jet wiping process, which is widely employed for controlling the final zinc-alloy coating thickness of a moving steel strip in the continuous hot-dip galvanizing process. In this study, large eddy simulation (LES) was employed to determine the effect of lower velocity symmetric auxiliary jets on main jet stabilization and coating thickness reduction during the gas jet wiping process. For validation purposes, experimental measurements of coating thickness were also carried out for the prediction of final coating thickness via a novel prototype multi-slot air knife used as the wiping actuator. Good agreement was found between the experimental measurements and model predictions for the coating weight, which also confirmed the applicability of the Elsaadawy et al.1 model for the prediction of final coating weight for the multi-slot air knife geometry used. It was found that the jet flapping observed during single jet wiping could be prevented through use of the multi-slot air knife operating with lower velocity symmetric auxiliary jets (Rea/Rem =  0.45) situated on both sides of the main jet. The auxiliary jets modified the flow field in the main jet shear layer and diminished the formation of alternating vortices, which are the main cause of jet flow oscillations. As a result, a stabilized impinging flow with a longer potential core was found for the multi-slot jet configuration. This led to increased pressure gradient and increased shear stresses in the vicinity of the wiping region and, consequently, lower coating weights were obtained through use of the multi-slot air knife compared to the conventional single slot jet. Note de contenu : - Analytical model of film thickness - Experimental setup - Numerical simulation - Results and discussion - Table 1 : Working liquid properties in the experimental facility DOI : https://doi.org/10.1007/s11998-021-00570-1 En ligne : https://link.springer.com/content/pdf/10.1007/s11998-021-00570-1.pdf Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=37152 [article]

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Numerical investigation of multiple-slot jets in air-knife wiping / A. Yahyaee Soufiani in JOURNAL OF COATINGS TECHNOLOGY AND RESEARCH, Vol. 14, N° 5 (09/2017)  

[article]  inJOURNAL OF COATINGS TECHNOLOGY AND RESEARCH > Vol. 14, N° 5 (09/2017) . - p. 1015-1025 Titre : Numerical investigation of multiple-slot jets in air-knife wiping Type de document : texte imprimé Auteurs : A. Yahyaee Soufiani, Auteur ; J. R. McDermid, Auteur ; Andrew N. Hrymak, Auteur ; F. E. Goodwin, Auteur Année de publication : 2017 Article en page(s) : p. 1015-1025 Note générale : Bibliogr. Langues : Américain (ame) Catégories : Acier L'acier est un alliage métallique utilisé dans les domaines de la construction métallique et de la construction mécanique. L'acier est constitué d'au moins deux éléments, le fer, très majoritaire, et le carbone, dans des proportions comprises entre 0,02 % et 2 % en masse1. C'est essentiellement la teneur en carbone qui confère à l'alliage les propriétés du métal qu'on appelle "acier". Il existe d’autres métaux à base de fer qui ne sont pas des aciers comme les fontes et les ferronickels par exemple. Enduction par filière Galvanisation Lame d'enduction Matériaux -- Epaisseur Métaux -- Revêtements protecteurs Revêtement métallique Zinc Index. décimale : 667.9 Revêtements et enduits Résumé : Gas-jet wiping using an air knife is an effective hydrodynamic method to control the coating thickness of zinc on a moving steel substrate in the continuous hot-dip galvanizing process. The current generation of single-slot air knives is widely used in the galvanizing industry but has limitations in producing low coating weights at the higher line speeds desired for the current generation of automotive sheet steel products. In this work, a novel configuration of a multiple-slot jet (multijet) air knife is investigated through numerical simulations as an alternative to the traditional single-slot air knife. The aim of this study is to investigate the sensitivity of the coating weight to the pressure and shear stress profiles in order to determine whether there are operating regions that are more robust to air-knife geometry changes. A modified geometry for the multislot air knife is proposed based on computational fluid dynamics results obtained from a parametric study. The effects of different operating conditions such as the main jet Reynolds number (Rem), auxiliary jet Reynolds number (Rea), and jet-to-wall distances (Z/D) on the final coating thickness were investigated. The results of the modeling showed that by setting the auxiliary jet Reynolds number at a fraction (25%) of the main jet Reynolds number, lighter coating weights can be achieved for higher strip velocities and higher wall-to-jet distances as compared to the single-slot jet design. It is believed that this geometry will provide a robust operating window to enable the prototype design to be employed in the industrial setting. Note de contenu : - Analytical model of film thickness - Numerical modeling - Boundary conditions and grid generation - Validation - Results and discussion : Effect of Da - Effect of auxiliary jet tilt angle (h) - Effect of a - Effect of s - Effect of jet-to-wall distance - Effect of main jet Reynolds number - Effect of auxiliary jet Reynolds number effect DOI : 10.1007/s11998-017-9963-0 En ligne : https://link.springer.com/content/pdf/10.1007%2Fs11998-017-9963-0.pdf Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=29137 [article]

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