Processing of thermogram sequences to determine the rotation rate of a vortex flame

We study vortex flame radiation in laboratory conditions. A fire torch was burning from a tank, which was fixed at the axis of uprising swirl airflow. Ethanol was used as a fuel. Processing of a sequence of thermograms of a swirling torch is described. The vortex flame revolutions were calculated using FFT of time pulsations of a signal from a thermal imaging system.