Studying the development of evaporation front interface in Freon R21 at non-stationary heat release

The work is aimed at investigation of dynamic and structural characteristics of the self-sustained evaporation front in freon R21 under the conditions of free convection. The results demonstrate the presence of two typical zones in the diagram of dependence of front propagation velocity on heating surface overheating. Formation of small-scaled fast growing disturbances was detected at the interface. The diagram of stability of evaporation front interface, built by the Landau theory, was proposed. The obtained experimental data were analyzed from the standpoint of instability development at intense evaporation. It is shown that development of interface instability for perturbation scales of about layer thickness corresponds to the area of more intense evaporation.