Experimental and numerical investigation of n-heptane/air counterflow nonpremixed flame structure

An experimental and numerical investigation of prevaporized n-heptane nitrogen-diluted nonpremixed flames is reported. The major objective is to provide well-resolved experimental data regarding the structure and emission characteristics of these flames, including profiles of major species (N-2, O-2, C7H16, CO2, CO, H-2), hydrocarbon intermediates (CH4, C2H4, C2H2, C3Hx), and soot precursors (C6H6). A counterflow flame configuration is employed, because it provides a nearly one-dimensional flat flame that facilitates both the detailed measurements and simulations using comprehensive chemistry and transport models. The measurements are compared with predictions using a detailed n-heptane oxidation mechanism that includes the chemistry of NOx and polycyclic aromatic hydrocarbon formation. The measurements are compared with predictions using a detailed n-heptane oxidation mechanism that includes the chemistry of NOx and polycyclic aromatic hydrocarbon formation. Measurements and predictions exhibit excellent agreement for temperature and major species profiles (N-2, O-2, n-C7H16, CO2, CO, and H-2), reasonably good agreement for intermediate species (CH4, C2H4, C2H2, and C3Hx), but significant differences with respect to benzene profiles. Consequently, the benzene submechanism was synergistically improved using pathway analysis and measured benzene profiles.