EFFECT OF NOZZLE DIAMETER ON THE REWETTING J. OF HOT SURFACES

Abstract

When a hot metal surface is impinged by a liquid jet, due to the superheat involved, the jet is not able to establish contact with the hot metal surface instantaneously. After a few milliseconds of time of impact, the contact is made, accompanied by intense vapor generation During the process of rewetting, the geometry involves, a circular wetted region, circumscribed by radially advancing wetting front and the unwetted zone, outside. Rewetting is the occurrence of the establishment of contact with the hot surface. There are three important parameters that serves as element to the study of rewetting. These are Rewetting temperature, Rewetting velocity and wetting delay. The present study aims at understanding the l'ransient nature of rewetting phenomena on a flat ss-plate Grade-302 and to evaluate the parameters describing it at the stagnation point. A real time estimation of rewetting velocity is presented using High speed camera, which provides rewetting velocity at every instant of' wetting front advancement