Numerical Description of the Structure of Counterflow Heptane-Air Flames UsingDetailed and Reduced Chemistry With Comparison to Experiments

摘要

Numerical calculations were performed using a simplified chemical kineticmechanism to determine the structure of counterflow heptane-air diffusion flames. The configuration used is a diffusion flame stabilized in the vicinity of a stagnation plane which is formed by directing an oxidizing gas flow onto the vaporizing surface of a pool of heptane. The elementary chemical kinetic mechanism referred to as the starting mechanism, consists of forty elementary reactions. The predicted structure of the flame using the starting mechanism was found to agree reasonably well with previous measurements. The calculations suggest that the outer flow in the experiments cannot be modeled using strictly rotational or strictly irrotational flow boundary conditions. Reduced chemical kinetic mechanisms, consisting of six and four overall steps, were deduced from the elementary chemical kinetic mechanism. The predicted structure of the flame using flame reduced mechanisms agree reasonably well with that calculated by using the starting mechanism. The results suggest that a reduced four-step chemical kinetic mechanism can predict the structure of the flame fairly accurately.