Laminar Burning Velocities of Iso-Octane-Air Mixtures — A Literature Review

A literature survey of the laminar burning velocity behaviors of iso-octane-air mixtures has been conducted with a view to recommending a suitable correlation for use in spark ignition engine combustion work. This comprised an initial study of some burning velocity measurement techniques and then considered laminar burning velocity as a function of unburnt gas temperature, dilution, equivalence ratio and pressure. To provide more definitive guidelines, especially with regard to the pressure effect, other hydrocarbon fuel burning velocity data has been reviewed. The recommended correlation utilises the Heimel and Weast (3) atmospheric pressure values with dilution catered for by the Metghalchi and Keck (44) modification. The pressure attenuation was found to vary with equivalence ratio in such a way that the negative pressure exponents increased as mixtures became weaker and richer. This is significant in terms of the trend toward combustion at leaner mixtures. The exponents themselves decrease with unburnt gas temperature increase and this raises the possibility of their becoming positive at high temperature levels.