BOILING ON FREE-FALLING SPHERES: DRAG AND HEAT TRANSFER COEFFICIENTS
ZVIRIN, Y.; R HEWITT, G.; KENNING, D. B. R.; ZVIRIN, Y.; Faculty of Mechanical Engineering, Technion; R HEWITT, G.; Faculty of Mechanical Engineering, Technion; KENNING, D. B. R.; Faculty of Mechanical Engineering, Technion
Журнал:
Experimental Heat Transfer
Дата:
1990
Аннотация:
AbstractExperiments have been conducted to measure drag (Cg) and heat transfer coefficients (h) and to study the boding nature on heated spheres free-falling in saturated and subcooled water. Simultaneous measurements of the transient sphere velocity and temperature during the fall enabled calculation of cD, heat fluxes and h values. It has been found that the drag decreases with the initial sphere temperature, T0. The measured results, as well as still and motion photography, show that at10⩾ 450° Cfilm boiling pre vaih, with low heat fluxes at the beginning of the transient. In some cases the film collapses, leading to a transition to disturbed-film and micro-bubble regimes, associated with larger heat fluxes and also solid-liquid interactions, with lateral motion of the sphere )“ shoot-off” )
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