Abstract:

A thermodynamic model to calculate burning speed of methane-air-diluent mixtures from the measured dynamic pressure rise of a combustion process in a chamber has been developed. The effect of automotive exhaust gas on the burning speeds was measured using a mixture of 86 % N2 and 14 % CO2 as the diluent. Photographic observations were made through the end windows in the cylindrical chamber using a high-speed charged coupled device (CCD) camera with variable speed of up to 8000 frames/second. The measured values of burning speeds have been compared with laminar burning speeds calculated using the PREMIX flame speed code and the GRI-Mech 3.0 mechanism. This thermodynamic model is valid for a wide range of high temperatures and pressures and the results agree well with the measurements under these conditions when the flames are smooth or cracked and lean or stochiometric.

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