Fast reaction nonpremixed combustion

Abstract

Recent measurements in turbulent, single-phase, reacting flows are reviewed. Attention is confined to nonpremixed flows at the fast reaction limit, which is defined as conditions where rates of reaction are fast enough to maintain local equilibrium. Reactant combinations considered include: hydrogen/air, carbon monoxide/air, hydrogen/fluorine, nitric oxide/ozone, acid/base (in liquids) and the dissociation of nitrogen tetroxide in warm air. Criteria for the fast-reaction limit, as well as the laminar flamelet concept, are discussed in some detail. Other aspects of measurements in these systems are also discussed, e.g. effects of initial and boundary conditions; types of averaging; and the interpretation of velocity, temperature and other scalar property measurements. Existing measurements in round free jets, plane free shear layers and wall boundary layers are summarized and discussed. Experimental difficulties in controlling hydrodynamic and reaction variables are substantial, even in these relatively simple flows; therefore, no existing data set is completely satisfactory for r definitive evaluation of methods of analyzing turbulent reaction processes at the fast-reaction limit. Recent measurements in round, free-jet, hydrogen/air diffusion flames, using optical diagnostics for structure measurements, come closest to this ideal; therefore, these results are discussed in detail and sources of tabulated data for use during model evaluation are cited.