Species Concentration and Temperature Measurements in a Lean, Premixed Flow Stabilized by a Reverse Jet

Abstract

The chemical and thermal structure and the emission performance of an aerodynamic flameholder are presented and examined. Recirculation is established by injecting a premixed jet into an opposing mainstream of premixed reactants. The injection of the jet directly into the recirculation zone provides a control of the stabilization zone mixture ratio, temperature, and size not found in bluffbody flameholding. The size and stoichiometry of the recirculation zone is dictated by the jet velocity and mixture ratio respectively. A parametric study of the controlling variables (main and jet stream velocities, main and jet stream equivalence ratios) reveals the partitioning between the recirculation zone and wake in both the heat release and pollutant production. An examination of the emission indexes and flowfield profiles of temperature and species concentration establishes the influence and control of jet and mainstream conditions on pollutant production. A reduction in jet velocity and/or an enrichment of the jet, for example, effects a substantial change in NO_x emission. Further, jet enrichment extends the lean blow-off limit of the mainstream. There exists a point, however, beyond which the reaction is not supported in the wake and further leaning of ihe mainstream results in a substantial emission of unspent fuel.

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Notes on contributors

M. D. McDANNEL

Present address: KVB Engineering, Inc., P.O. 19518, Irvine, CA 92714.

P. R. PETERSON

Present address: Pacific Environmental Services, 1905 Chapel Hill Road, Durham, NC 27707.