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This paper concerns with the problems of cooling down of various high-voltage electric power devices of the megawatt range. When flowing around the current-carrying and other elements of these devices a formation of non-stationary vortices can take place. Therefore, a detection and visualization of vortex structures appearing at the coolant flowing through channels with the complicated geometry is an important task. The generation of whirlwind structures (non-stationary vortices) was performed above this substrate surface (aluminum alloy sheet) by the unstable air stratification obtained by heating it up from below. We have used the mcm sized particles of magnesia deposited on the substrate surface to visualize the generated free non-stationary vortices. The frame-by-frame view of recordings obtained by the direct video-registration at various thermal modes allowed performing of the qualitative analysis of the spatio-temporal structure of non-stationary vortices and obtaining a lot of their important integral parameters (visible height, diameter, lifetime, quantity of vortices, base motion velocity, etc.). There had been considered physical basements of processing of flow patterns obtained by the PIV method with the use of the measurer of fields of velocities POLIS (Russian “ПОЛИС”, the instrument is developed by the S.S. Kutateladze Institute for Thermophysics of the Siberian Branch of RAS, Novosibirsk) in order to recover the fields of instantaneous velocities of vortex structures. The results of the visualization of free non-stationary vortices obtained by the direct video filming and vector fields of instantaneous velocities, obtained by the PIV (Particle image velocimetry) method, have been presented. The developed technique of visualization and diagnosis of free non-stationary vortices can be used for development of the state-of-the-art cooling systems of high-power electric devices.

Visualization of whirlwind (non-stationary vortex) structures aimed to the improvement of cooling systems of electric power devices