The structure and stability of the laminar counter-flow partially premixedmethane/air triple flame

The flame stability map defining the regime of existence of a counter-flowi ng laminar partially premixed methane-air triple flame has been determined using OH planar laser-induced fluorescence (PLIF). The stability limits wer e determined through the observation of flame merging and flame extinction, a function of rich and lean equivalence ratios, and mean axial strain rate . Relatively quantitative OH species profiles and Rayleigh scattering profi les have been measured for three flame conditions. Axial flow velocity prof iles, and nozzle exit velocity profiles have been determined for two of the three conditions using 1-D laser Doppler velocimetry (LDV). The diffusion flame extinction axial velocity profile has been measured, and the local ex tinction axial strain rate has been determined to be 710 s(-1). (C) 1999 by The Combustion Institute.