High-Speed Thermographic Study of Convective Turbulence Characteristics over a Heated Surface

Abstract

The results of laboratory experiments on determining the characteristics of convective turbulence over a heated metal surface at different heights and temperatures are presented. We used the high-speed thermography and a high-speed IR camera, which allowed imaging the temperature field of low-inertia paper targets hung up above the heated surface simultaneously throughout the vertical plane of the field of view of the camera. Based on fluctuations in the temperature field of the target surface, we determined the heat transfer coefficient, the convective flux intensity, the total flux, and the amount of heat generated during measurements at different heights above the surface. The energy spectra of convective turbulence are plotted under various turbulent conditions. The analysis of the turbulence spectra shows the presence of an inertial interval with a slope close to the 8/3 power law for all considered heights above the heated surface, temperatures, and turbulence conditions. Characteristics of convective turbulence we found can be used when testing different laser beam adaptive optics control systems, studying the propagation of vortex laser beams and combustion centers, which are also characterized by convective turbulence with further transition to atmospheric turbulence induced by the combustion energy.