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Título del libro: 65th Abm International Congress, 18th Ifhtse Congress And 1st Tms/abm International Materials Congress 2010
Título del capítulo: Effect of the hydrodynamic conditions on the vapor film during forced convective quenching

Autores UNAM:
JOSE BERNARDO HERNANDEZ MORALES;
Autores externos:

Idioma:
Inglés
Año de publicación:
2010
Palabras clave:

Fluid velocities; High cooling rates; Hydrodynamic conditions; Phase fraction fields; Physical conditions; Quenching process; Vorticity gradients; Wetting fronts; Hydrodynamics; Kinematics; Mathematical models; Models; Probes; Quenching; Velocity; Vorticity; Wetting; Vapors


Resumen:

To achieve the high cooling rates required during quenching processes, the parts are quenched in agitated liquid baths which modifies boiling phenomena at the part-fluid interface and, therefore, the thermal field evolution within the part. In spite of this, the interactions between fluid hydrodynamics and wetting front kinematics have not been investigated in detail. In this paper we studied the effect of vorticity and pressure gradients near the part surface on wetting front kinematics during forced convective quenching by means of a mathematical model which couples the velocity, thermal and phase fraction fields. The particular physical condition studied was that of water at 60°C flowing parallel to a flat-end cylindrical stainless steel probe, for which experimental results were already available. The computed pressure and vorticity fields show larger gradients near the probe end as the fluid velocity increases. This behavior favors a thicker vapor film near the probe base reducing heat transfer to the quenching bath locally. In contrast, low pressure and vorticity gradients occurring for low fluid velocities favor a uniform vapor film. A direct consequence of the nonuniform vapor film thickness occurring at high velocities is a significant thermal gradient along the probe axis which favors distortion. Copyright © (2010) by Associação Brasileira de Metalurgia Materiais e Mineração (ABM).


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