Peculiarities of the initialization and dynamics of the quench front on an extremely overheated plate cooled by a falling film of a cryogenic fluid

Abstract

Quenching is a generally accepted term for the process of rapid cooling of a solid body that is superheated above the temperature of the thermodynamic limit of a liquid superheat. The paper presents the results of computational experiments simulating the quenching of a high-temperature vertical copper plate by a gravitationally flowing film of liquid nitrogen. The peculiarities of the initialization and dynamics of the quench front in the transition process are investigated. The initial temperature of the test sample was higher than the Leidenfrost temperature and even higher than the critical temperature, which excluded the possibility of long-term stable liquid-solid contact. An improved numerical model of quenching is implemented, which assumes at the time of the quench front initialization an unsteady local contact of the liquid with the extremely overheated surface in the vicinity of the upper boundary of the heater. A dynamic pattern of the running quench front was obtained numerically, which satisfactorily correlates with that observed in cryogenic experiments by the high-speed digital video camera. The reliability of the results obtained numerically is confirmed by direct comparison with experimental data on the velocity and the shape of the quench front.