Dynamical Study of a Molten Boundary Layer Ejected by Laminar Gas Flow

Abstract:

We consider in the present work the fusion laser cutting of stainless steel sheets under a nitrogen laminar gas jet. The molten metal is treated as a laminar and steady viscous incompressible fluid. The mathematical model describing our problem is set in terms of Navier-Stokes equations, solved numerically using the finite differences method, where the effect of the gas jet velocity on the molten boundary layer is considered. The generated shear stress occurring on the gas-liquid interface and its contribution in the momentum is carried out, and it is found that when the skin friction and the shear stress decrease, the thickness and the velocity at the edge of the molten boundary layer increase along the kerf surface. The layer thickness reduces when the assisting gas velocity is increased.

• Periodical: Defect and Diffusion Forum (Volume 348)
• Pages: 88-93
• DOI: https://doi.org/10.4028/www.scientific.net/DDF.348.88
• Online since: January 2014
• Authors: Samia Aggoune, El Hachemi Amara
• Keywords: Boundary, Cutting, Flow, Friction, Fusion, Gas, Laser, Layer

References

[1] B. S. Yilbas, A. Z. Sahin, Oxygen assisted laser cutting mechanism - a laminar boundary layer approach including the combustion process, Optics and Lasers Technology 27 (1995) 175–184.

DOI: 10.1016/0030-3992(95)93638-8

[2] D. Petring, Laser cutting processes, in: J. F. Ready and D. F. Farson (Eds. ), LIA Handbook of Laser Materials Processing, Magnolia Publishing, Orlando, FL, 2001, p.425–426.

[3] E. Beyer, T. Himmer, M. Lütke, F. Bartels, A. Mahrle, Stuttgart Laser Technologies Forum, German Scientific Society of Laser Technology, Stuttgart, (2008).

[4] M. Vicanek, G. Simon, Momentum and heat transfer of an inert gas jet to the melt in laser cutting, Journal of Physics D Applied Physics 20 (1987) 1191–1196.

DOI: 10.1088/0022-3727/20/9/016

[5] H. Golnabi, M. Bahar, Investigation of optimum condition in oxygen gas-assisted laser cutting, Optics and Laser Technology 41 (2009) 454-460.

DOI: 10.1016/j.optlastec.2008.08.001

[6] W. Schulz, D. Becker, J. Franke, R. Kemmerling, G. Herziger, Heat conduction losses in laser cutting of metals, Journal of Physics D Applied Physics 26 (1993) 1357-1363.

DOI: 10.1088/0022-3727/26/9/003

[7] W. Schulz, V. Kostrykin, M. Nießen, J. Michel, D. Petring, E. W. Kreutz, R. Poprawe, Dynamics of ripple formation and melt flow in laser beam cutting, Journal of Physics D Applied Physics 32 (1999) 1219–1228.

DOI: 10.1088/0022-3727/32/11/307

[8] E. Abdulahdi, Etude de la découpe d'acier au carbone par laser CO2, Modélisation thermique et métallurgique du procédé, Thèse d'Etat de l'Ecole Nationale Supérieure des Arts et Métiers, Paris, (1997).

[9] C. Mas, R. Fabbro, Y. Gouedard, Steady-state laser cutting modeling, Journal of Laser Applications 15 (2003) 145–152.

DOI: 10.2351/1.1567749

[10] H. Schlichting, Boundary Layer Theory, McGraw-Hill, New York, (1982).