Analysis of Thermal Radiation Emitted from Partially Premixed Methane–Air Jet Flames

According to accident databases, severe accidents, usually leading to catastrophic events, have originated from 50% of registered jet fires. This “domino effect” is usually caused by the high heat fluxes emitted from jet flames, and the flame impingement. This study analyses the thermal radiation emitted from partially premixed methane–air jet flames, obtained with volumetric fuel flows of 7 L/min, 8 L/min, and 9 L/min. The main geometrical features of the flames (lift-off distance, radiant flame length, and flame area) were obtained by analysing over 500 images, then used to calculate the parameters involved in the solid flame radiation model to determine the heat flux emitted. The view factor was calculated for finite areas, while emissivity was obtained by correlating the average flame diameter of each flame with a soot particle constant. The results obtained from the experiments clearly identify three general regions for the flame temperature and heat flux profiles, as a function of the flame’s axial position. The maximum flame temperature and heat flux are reached in the second region, at approximately 73% of the flame’s axial position. The geometric considerations used throughout the present work allowed for more accurate thermal radiation values in regard to other known techniques.