Toward Comprehensive Understandings on Flammability Limits of Low-LewisNumber Mixtures

Abstract

Studies on flammability limits are briefly reviewed. Firstly, theory for describing combustion limit of planar propagating flame is introduced. Experimental methods to obtain flammability limits are then reviewed, namely the constant-volume bomb method and the counterflow flame method. Based on various studies, flammable regions of different types of flames were found to vary considerably, depending on the flame configuration, the Lewis number, and flame stretch. Deeper understandings were achieved through microgravity experimental results, such as the Self Extinguishing Flames, C shaped extinction curve and flame balls. Finally, preliminary experimental results to construct an unified flammability-limit theory are introduced. Results are then compared to 2D and 3D computational results showing a qualitative match to the experimental observations.