The data presented here is from an atmospheric pressure, axisymmetric, coflowing, nonpremixed laminar flame. The burner shares all of the characteristics of the burners used in previous studies. Flames are generated with a burner in which the fuel flows from an uncooled 4.0 mm inner diameter vertical tube (wall thickness 0.38 mm, parabolic flow) into a concentric, 74 mm diameter air coflow (plug flow). Older versions of the burner used a 50 mm diameter coflow, but the same flame structure is expected. The details of the burner have been kept consistent with previous studies in order to provide continuity between earlier experiments and numerical calculations, and further studies. The fuel and oxidizer flows are set with an average cold-flow velocity of 35 cm/sec. The flame is lifted above the burner surface (~ 6 mm for methane, ~ 3 mm for ethylene), preventing heat transfer from the flame to the burner. As a result, adiabatic boundary conditions can be used at the burner surface for the numerical calculations. Various fuels (e.g., ethylene and methane) have been investigated with differing percentages of nitrogen dilution (by volume). Dilution of the fuel with inert nitrogen provides the ability to vary the soot loading within the flame. Further, a speaker is placed in the fuel plenum to allow for modulation of the fuel flow rate to produce forced, time-varying flames.
