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Titolo:
Visualization of Marangoni convection in simulated weld pools containing asurface-active agent
Autore:
Limmaneevichitr, C; Kou, S;
Indirizzi:
Univ Wisconsin, Dept Mat Sci & Engn, Madison, WI 53706 USA Univ WisconsinMadison WI USA 53706 Mat Sci & Engn, Madison, WI 53706 USA
Titolo Testata:
WELDING JOURNAL
fascicolo: 11, volume: 79, anno: 2000,
pagine: 324S - 330S
SICI:
0043-2296(200011)79:11<324S:VOMCIS>2.0.ZU;2-P
Fonte:
ISI
Lingua:
ENG
Soggetto:
FLUID-FLOW; TENSION; HEAT;
Keywords:
Marangoni convection; surface-active agent; laser beam welding; weld pool; gravity-induced; buoyancy convection; flow visualization;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Engineering, Computing & Technology
Citazioni:
26
Recensione:
Indirizzi per estratti:
Indirizzo: Limmaneevichitr, C Univ Wisconsin, Dept Mat Sci & Engn, 1509 Univ Ave, Madison, WI 53706 USA Univ Wisconsin 1509 Univ Ave Madison WI USA 53706 6 USA
Citazione:
C. Limmaneevichitr e S. Kou, "Visualization of Marangoni convection in simulated weld pools containing asurface-active agent", WELDING J, 79(11), 2000, pp. 324S-330S

Abstract

The theory that a surface-active agent can cause weld pool Marangoni convection to reverse itself to go inward along the pool surface and downward toward the pool bottom and result in deeper weld penetration - was proposed by Heiple and Roper in 1982 and studied worldwide since then. To actually observe such a flow pattern, a simulated transparent weld pool of NaNO3 (10 mm in diameter) was heated with a defocused CO, laser beam to induce Marangoni convection, and C2H5COOK was used as a surface-active agent to cause flow reversal. A laser light-cut technique was used to reveal convection in the pool. With pure NaNO3, convec tion was outward along the free surface anddownward along the pool wall. However, when C2H5COOK was present (e.g., at0.5 and 1 mole-%), convection slowed down. When more C5H5COOK was present (e.g., at 1.5 and 2 mole-%), convection was reversed to go inward along thepool surface and downward along the pool axis. Since this is in the opposite direction of gravity-induced buoyancy convection, Marangoni convection clearly dominated in the pools. In stationary laser beam welding, NaNO3 containing 1 mole-% C2H5COOK showed deeper weld pools and inward surface flow, while pure NaNO3 showed shallower weld pools and outward surface flow. Thisis consistent with the reversal of Marangoni convection caused by C2H5COOKobserved in the flow visualization.

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Documento generato il 03/04/20 alle ore 20:11:17