Thermographic Visualization of the Thermal Fields from Plasma Actuators Through Discharge Chamber Windows

Abstract

The paper presents the panoramic visualization of thermal fields in the discharge section of the UTRO-3 experimental device of the Lomonosov Moscow State University Faculty of Physics. The main purpose of the work was to study the heating and cooling processes in a rectangular channel region under the influence of pulsed surface high-current discharges sliding over the dielectric surface, taking into account the supersonic flow in a channel with an obstacle structures. A pulsed surface discharge initiated in a 24x48 mm channel in a high-speed flow (the delay time after the shock wave passage is up to 0.4 ms) is localized mainly in the downwind region behind the reverse step (rectangular insert). The discharge produces a pulsed (submicrosecond) energy input with a length of 30 mm in the localization zone. As a result, there is a short-term heating of the section of the channel wall adjacent to it. Using infrared thermographic imaging through the chamber quartz windows transparent to IR radiation, it was recorded in the discharge chamber that the induced discharge plasma noticeably heats the surface of the flat channel wall. Based on the obtained data of panoramic visualization with an exposure up from 100 µs, we studied the cooling time of the channel walls in the downwind region evolution, heated rapidly due to the interaction with the surface discharge plasma, at various free flow velocities.