Experimental investigations and computational simulation of acetylene-oxygen flames from near stoichiometric to sooting conditions

Abstract

Mole fraction and temperature profiles have been measured by hypercritical expansion nozzle sampling followed by mass spectrometric analysis, and by the Na-D-line reversal method, respectively, in burner-stabilized laminar flat C 2 H 2 −O 2 flames diluted by Ar. The formation of higher hydrocarbons like C 3 H 4 , C 4 H 2 is emphasized because of their importance as potential precursors of soot. Unburnt gas compositions range from stoichiometric mixtures to very fuel rich conditions leading to sooting flames. For interpretation of the measurements the corresponding one-dimensional conservationequations have been solved using a reaction mechanism resulting from an extensive literature evaluation. It can be shown that (independently of the mechanism used for the formation of C 4 H 2 ) in sooting acetylene flames about 35% of the C 2 H 2 is reacting via C 4 H 2 , which may be formed by C 2 H resulting from abstraction reactions of H and OH with C 2 H 2 at high temperature. The consequences of this mechanism (e.g. the importance of the chemistry of diacetylene) for flames of other fuels are discussed.