Flame size, heat release, and smoke points in materials flammability

The concept of using the flame size as a surrogate for heat release rate (HRR) has been explored. A technique for simultaneously obtaining the HRR, flame size (height and area), and the smoke point of the flame solely from visual images has been developed. The technique has been demonstrated on gaseous flames (methane, propane, ethylene, and propylene) and explored for five burning solid polymers. Estimations of the flame area from images of the stoichiometric contour based on the CH chemiluminescent region of the flames yielded a good linear correlation with measured HRR, valid for all of the gaseous and solid compounds tested, for burning rates above or below the smoke point. In contrast, flame heights and luminous images (i.e., from soot emission) were confounded by differing behavior above and below the smoke point.