BURN-OUT HEAT TRANSFER IN UNSTEADY STATE HEAT GENERATION IN A CRYOGENIC FLUID.

Measurements are presented of unsteady-state critical flux in step-wise and pulse regimes of heat generation on cylindrical heaters placed in nitrogen. It is shown that convection induced in a fluid by preliminary heat generation substantially increases the unsteady state critical heat flux. Based on the analysis of the motion pictures of the liquid boiling, a model is proposed to describe the mechanism of crisis origination in unsteady-state heat generation conditions which allows one to derive an analytical expression for the minimal critical heat flux.