Experimental study of the effect of structured capillary-porous coating on rewetting dynamics and heat transfer at film cooling by liquid nitrogen

The results of an experimental study of the dynamics of rewetting and heat transfer on a copper plate with a structured capillary-porous coating, obtained by directional plasma spraying at film flow of liquid nitrogen are presented. The experiments were carried out at different orientations of the coating relative to the flow of the liquid. A comparison with the experimental data obtained on a smooth heater is made. It is shown that the presence of a coating has a significant effect on the character of the temperature curves and reduces the total cooling time of the plate during rewetting by more than three times as compared to the uncoated plate, but it does not significantly affect the heat transfer under conditions of stationary heat release. Data of high-speed video recording of processes are presented. (paper)