Dynamic characteristics of the interface of the self-sustaining evaporation front in freon-21
The paper presents the results of experimental research of the propagation dynamics of self-sustaining evaporation front at stepped heat release on a horizontal cylindrical surface in Freon-21 at free convection. The experimental data on propagation velocity and structure of evaporation fronts were obtained; the spectrum of interface pulsation was analyzed at different metastable characters of the thermal layer. It is shown that a significant change in working section roughness did not lead to a considerable change in the velocity of evaporation front propagation. The connection between frequency of the main harmonics of interface velocity pulsation and velocity of evaporation front propagation was determined. It is shown that the ratio of amplitude of the main harmonics of evaporation front velocity pulsation to the average front velocity decreases with a rise of front velocity in the range of up to 0.5 m/s. At higher velocities the ratio stays constant.