A Shock-Tube Study on the Ignition Lag of Gaseous Fuels

Abstract

A study was made on the ignition delays of n-butane-oxygen mixtures to clarify the high-temperature oxidation mechanism of gaseous higher-hydrocarbon fuels. The ignition delays were measured in a shock tube by detecting the visible emissoin from the reactants employed as driven gases. Experiments were carried out for various equivalence ratios and for a range of shocked-gas temperatures ancl pressures. Using n-butane-argon mixtures as driven gases of the shock tobe the cracking reaction, supposed to occur prior to ignition, were observed by means of the integrated schlieren method and the gas chromatography. A reaction model for the oxidation of n-butane was proposed, which was similar to the well-established reaction model for hydrogen-oxygen mixtures, and iginition delays were calculated on the basis of this reaction model. Calculated igniiotn delays and the dependence of the apparent activation energy on the equivalence ratios agreed fairly well with experimental results.