Experimental and modeling study of laminar flame speed and non-premixed counterflow ignition of n-heptane
Laminar flame speeds were determined for n-heptane-oxygen-nitrogen mixtures over the pressure range of 0.5-2 atm and equivalence ratio range of 0.7-1.4, using the counterflow twin-flame technique. For pressure at or below 1.5 atm, the laminar flame speeds were collected for n-heptane/air mixtures, whereas the data at 2 atm are reported for diluted air of 18% O2, 82% N2. These experimental data, together with those acquired previously on the non-premixed counterflow ignition temperature of n-heptane determined over the same range of pressure, were simulated with a high-temperature, detailed kinetic model of n-heptane oxidation. After demonstrating satisfactory comparison between the model and experiment, the influence of pressure-induced kinetic effects on the laminar mass flux was analyzed through a computational determination of the overall reaction order. The non-premixed ignition temperature responses were in addition analyzed by numerical sensitivity analysis on reaction kinetics and fuel diffusion rate. The influence of uncertainties in the molecular transport on the model prediction of diffusive ignition is discussed.
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