Optical identification of the combustion of air-fuel mixture surrounded by non-combustible gas in a rapid compression machine

The influence of non-combustible gas injection on combustion rates in an engine cylinder with centrally positioned ignition point has been discussed. The flame temperature distribution and its changes were taken into account in this research. The analysis of the influence of exhaust gas content in the cylinder on the combustion process has been based on the interpretation of high speed camera images for the period from the ignition start to full flame coverage of the combustion chamber. Authors performed a comparative analysis of the combustion process thermodynamic parameters based on the obtained characteristics. In order to demonstrate the charge stratification influence and the proportion of flue gas in the cylinder, a flame propagation analysis was performed through high frequency image sampling and using the flame temperature distribution in the combustion volume. The two-color method was used for determining this temperature. A flame temperature distribution example at selected combustion process stages was presented as well as for the entire combustion process. A significant reduction in the area covered by the flame was shown to be the result of an increase in the flue gas proportion in the cylinder. The flame area reduction was found to be 46% when using a 25% EGR share, while with an EGR contribution of 40%, the flame area was decreased by 78%. The flame covered area reduction was the result of "fencing" of the flame from the cylinder walls by an exhaust gas layer. According to changes in the flame area, the largest share of high temperatures, in the range 1800-2000 K, has also decreased from around 19% to 23%.

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Opracowanie rekordu w ramach umowy 509/P-DUN/2018 ze środków MNiSW przeznaczonych na działalność upowszechniającą naukę (2018).