Effect of fuel dilution on jet flames in a heated and diluted co-flow

Abstract

imaged by laser diagnostic techniques are presented. The measurements are of nonpremixed jet flames in a hot and highly diluted co-flow. These conditions emulate those of Moderate and Intense Low Oxygen Dilution (MILD) combustion. This paper presents results on the effect of O2 co-flow level and fuel dilution on the structure of the flames for a fixed jet Reynolds number. A reduction of O2 in the oxidant stream is shown to lead to a substantial suppression of both OH and H2CO levels. Within lifted flames, in comparison to the fluctuating levels of OH, H2CO levels remain constant. Although beyond the aim of the current investigation, a peripheral observation has been made that flames in a lower O2 co-flow stabilise at jet velocities which are lifted at higher O2 levels.