MODELING OF EXTINCTION IN TURBULENT-DIFFUSION FLAMES BY THE VELOCITY-DISSIPATION-COMPOSITION PDF METHOD

The velocity-dissipation-composition probability density function (pdf ) method is used to model a turbulent CO/H-2/N-2-air-piloted jet diffu sion flame in the regime of extinction. The thermochemistry is modeled by a three-scalar simplified formulation obtained by the intrinsic lo w-dimensional manifold (ILDM) method. Calculations are performed for f ive different jet velocities, and the scalar pdfs are compared with ex perimental data. Overall good agreement is obtained between the calcul ations and the experimental results, with the only significant differe nce being the high level of scatter in the experimental data compared with the pdf results: reasons for this difference are discussed. The p df method is found to predict flame extinction at approximately the sa me jet velocity as that of the experiment. A small amount of local ext inction is observed in the pdf results for the high-jet-velocity cases .