Infrared Thermography of The Process of Surface Forest Fire Spread and Transition to Crown Fire

The transition from a surface forest fire to a crown fire was experimentally studied under laboratory conditions. Using noncontact infrared (IR) diagnostic methods within narrow spectral ranges of infrared wavelengths, the propagation speed of the fire front was determined, along with temperature changes at control points where the combustion transitions from a surface fire to a crown fire. The experiment was conducted under varying incoming airflow velocities and different canopy heights relative to the surface fire. In the infrared range, the radiation from the sample surfaces was recorded using a JADE J530SB thermal imaging camera equipped with an optical filter (2.5–2.7 μm), enabling temperature measurements within the range of 310–1500 K. To interpret the recorded radiation from the test samples, calibration data provided by the manufacturer of the narrowband optical filter was used.