Infrared Diagnostics of Turbulence in the Front of a Wildland Fire and the Formation of Induced Atmospheric Turbulence

Abstract

An infrared diagnostic of the scale of turbulence in the front of a natural fire is presented, as well as a comparison with the scale of turbulence in the air near the combustion source for a model grassland and crown fire. An analysis of the flame of a grassland fire reveals smaller turbulence scales than the flame of a crown fire. A fire-induced atmospheric turbulence at a height of 10 m is observed with the corresponding frequency of air temperature pulsation (0.1–6 Hz for a steppe fire and 0.1–3 Hz for a crown fire). The values of the structural functions of refractive index and temperature fluctuations are significantly higher than the background values and can be used for remote fire detection.