Abstract

Carbon monoxide time-histories and ignition delay times were measured in carbon dioxide diluted methane mixtures behind reflected shockwaves. Experiments were performed around 2 atm for a temperature range between 1650–2000 K. The experiments were performed for a mixture of XCH4 = 0.5%, XO2 = 1.0%, XCO2 = 8.5%, XAr = 90.0%. The mixture was chosen to minimize energy release during the experiment and a minimum of 2 ms was recorded for all experiments. The carbon monoxide time-histories were measured using a tunable diode laser absorption spectroscopy technique and measuring the absorbance at two different wavelengths to isolate the impact of carbon monoxide on the absorbance. Carbon monoxide was measured at a wavelength of 4886.94 nm while the interfering species was measured at 4891.17 nm. Each experiment was performed twice, with the pressure and temperature before combustion being matched to within the experimental uncertainty of the two experiments. The ignition delay times were measured using OH* radical emission to determine the time-scales of the experiments. All experiments were compared to detailed chemical kinetic mechanisms that can be found in the literature. The experimental results show that the detailed mechanisms from the literature were able to accurately predict the general profile of the carbon monoxide time-histories but under-predicted maximum concentration of CO being formed at these conditions.

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