Computational and Experimental Study of Molecular Growth in Forced, Time-Varying Flames

摘要

Time-varying flames are an important intermediate between laminar and turbulent combustion because they exhibit a larger range of combustion conditions than those observed in steady flames. Such flames may give insights into a variety of chemistry-flow field interactions important in turbulent combustion - all of which occur in a reproducible flame cycle. For the past decade, several groups have studied time-varying methane flames burning in air formed by imposing a periodic fluctuation to the fuel flow rate of a steady flame. The fuel for these flames has been "neat" methane, or diluted with either nitrogen or air. If the fuel flow perturbation is sufficiently large, these flames formed are distinguished by the formation of axisymmetric time-dependent, large-scale, vortical structures caused by buoyancy-driven flow instabilities. All of the results for this important class of flames clearly indicate that particle growth is greatly affected by the fuel flow perturbation. A combined computational and experimental study of molecular growth chemistry in forced, time-varying flames is currently being pursued. Early results of these studies will be presented, along with details of the burner configuration that has been adopted.