A Diffusion Flame Formed in a Low Supersonic, High-Temperature, Vitiated Oxidizer Flow

Abstract

Experiments were made in open coaxial jets of a Mach 1.26 oxidizer flow and a subsonic fuel flow; the ratio of the mass flux of the fuel flow to the oxidizer flow was 0.094; and city gas was used as the fuel. The inner fuel jet had an initial diameter of 13 mm and the outer oxidizer jet 36.7 mm; the oxidizer had a static temperature of 1350K and an oxygen mole fraction of 0.063. Pitot pressure, static pressure, total temperature, and species concentrations were measured in the combustion field. It was found that the flow pattern downstream of the fuel injector was like a wake having a recirculation zone in it. The flame was formed at the edge of the wake. The luminous zone was thin down to the end of the recirculation zone, and downstream of the recirculation zone the luminous zone rapidly thickened.