Analysis of Air Vortices Generation Process under Different Heating Conditions

The purpose of the study was to investigate the possibility of intensifying the process of wall-free concentrated air vortices generation by increasing the temperature instability of air. There exists a fundamental possibility of wall-free non-stationary thermal vortices generation without using mechanical twisting devices. Vortices generation was carried out over the underlying surface, namely aluminum sheet, by producing the unstable stratification of air heated from below. A simple experimental setup has been made, which makes it possible to change the air temperature gradient in the vertical direction. A series of experiments were performed in making the temperature stratification by simultaneously heating the air from below and cooling it from above. The air was heated by the controlled heating of the underlying surface using a gas burner. The air was cooled by means of dry ice located above the underlying surface. The dynamics of the vortices and their integral parameters (visible height, diameter) were determined by video recording. Single-frame analysis of this video recording made it possible to conduct a qualitative examination of the spatio-temporal structure of non-stationary vortex formations. The experiments carried out allowed us to make a conclusion concerning the intensification of the vortex formation process with an increase in the vertical air temperature gradient. This effect appeared as an increase in the average number of the observed vortices per experiment, as well as in the growth of their intensity, namely characteristic velocity, geometry and stability, namely lifetime

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