Open Access System for Information Sharing

Login Library

 

Article
Cited 14 time in webofscience Cited 0 time in scopus
Metadata Downloads

Aerodynamic investigation about the cause of check-mark stain on the galvanized steel surface

Title
Aerodynamic investigation about the cause of check-mark stain on the galvanized steel surface
Authors
Hyun Gi YoonGi Jang AhnKim, SJMyung Kyoon Chung
Date Issued
Nov-2009
Publisher
일본철강협회
Abstract
When galvanized steel strip is produced through a continuous hot-dip galvanizing process, the thickness of the adhered zinc film is controlled by impinging a thin plane nitrogen gas jet. In such a gas wiping process frequently there appears stain of check-mark shape. The check-mark stain is caused by non-uniform zinc coating over the surface. In order to find the main reason of the appearance of the check-mark stain, the unsteady compressible flow field is numerically simulated by using LES turbulence model for two cases of L/d=6.67 in the Case 1, 11.54 in the Case 2 where d is the nozzle width and L is the lip-to-plate distance. It was found that there are alternating plane-wise vortices near the impinging stagnation region, and that such alternating vortices move almost periodically to the right and to the left sides on the stagnation line due to the jet flow instability and alternating pressure peaks along the stagnation line. Since higher stagnation pressure removes more molten zinc adhered on the surface, the zinc coating thickness is thinner there. In addition, since the strip moves upward at a constant speed, the non-uniform coating surface is formed with a variety of patterns like "W", "V" and "X". The angle of the check-mark was calculated by using both the moving speeds of the steel strip and the sidewise movement of the vortices along the stagnation line. It was favorably compared with the experimental measurement.
Keywords
Slot impinging jet; coherent structure; vortex pair; LES; galvanized steel; SLOT-JET IMPINGEMENT; HEAT-TRANSFER; IMPINGING JETS; FLOW; COATINGS; PLATE; EDGE
URI
http://oasis.postech.ac.kr/handle/2014.oak/26339
ISSN
0915-1559
Article Type
Article
Citation
ISIJ INTERNATIONAL, vol. 49, no. 11, page. 1755 - 1761, 2009-11
Files in This Item:
There are no files associated with this item.

qr_code

  • mendeley

Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.

Views & Downloads

Browse