THE INITIAL TEMPERATURE AND N2 DILUTION EFFECT ON THE LAMINAR FLAME SPEED OF PROPANE/AIR

Abstract

Laminar flame speeds of propane/air mixtures were determined experimentally over an extensive range of equivalence ratios at room temperature, 500 K, 650 K, and atmospheric pressure. Nitrogen addition to simulate effects of exhaust gas dilution on the laminar flame speed was also studied at these conditions for selected equivalence ratios. The experiments employed the stagnation jet-wall flame configuration in which the flow velocity was obtained by using particle image velocimetry. The laminar flame speed was obtained using linear extrapolation to zero stretch rate. The measured flame speeds were compared with literature data and numerical predictions using a published detailed kinetic model (Qin, Z., Lissianski, V., Yang, H., Gardiner, W. C., Jr., Davis, S. G., and Wang, H., Proc. Combust. Inst., vol. 28, pp. 1663–1669, 2000). The predictions generally agree well with the experimental data. Both the data and model predictions reveal a quasi-linear relationship between the laminar flame speed and the dilution ratio, contrary to the nonlinear correlations commonly suggested in the literature. The linear dependence issue is numerically extended to include hydrogen and methane flame systems.