Experimental estimate of the laminar burning velocity of iso-octane in oxygen-enriched and CO2-diluted air

Oxygen-enriched combustion is of great interest for industrial applications, since membrane separation technology can be used. The objective of this work is to provide unique data on laminar burning velocity, a key parameter in real combustion development, for the oxygen-enriched combustion of an iso-octane/air mixture for various dilution (by air or CO₂) cases. Experiments were carried out in a stainless steel combustion chamber at atmospheric pressure and 373 K. The iso-octane was mixed with a mixture of O₂, CO_2, and N₂. The volume fraction of O₂ was varied from 21% to 29% and CO₂ was varied from 0% to 28%. The classical shadowgraphy technique was used to detect the reaction zone in order to deduce the un-stretched burning velocity, using a nonlinear methodology. All the experimental data were compared with the numerical results obtained with chemical kinetic schemes available in the literature. For further experimental investigations, a correlation is proposed to predict laminar burning velocity as a function of the quantity of O₂ and CO₂ in the gas mixture. Finally, analytical and experimental data concerning Markstein length are discussed.