The differential diffusion parameter, z = ξ(H) - ξ(C) is evaluated using recent single-point data collected in turbulent nonpremixed flames stabilised either by a pilot or on a bluff-body. Measurements are presented for flames of CH3OH, H2/CH4 and H2/CO fuel mixtures and over a range of jet Reynolds numbers. The effects observed in both bluff-body and pilot-stabilised flames are similar. Differential diffusion is generally found to decrease with increasing jet Reynolds number. The location of the reaction zone is found to be important in separating 'hydrogen rich' regions on the lean side from 'hydrogen deficient' on the rich side. This is true regardless of the parent fuel mixture. Profiles of mean z and its rms fluctuations are qualitatively similar in mixture fraction space, but in physical space, show a cross stream dependence. These findings are useful for modelling differential diffusion effects in turbulent combustion.
|Title of host publication
|Proceedings of the 1998 Thirteenth Australasian Fluid Mechanics Conference, Melbourne, Australia, 13-18 December 1998
|Number of pages
|Published - Dec 1 1998