Abstract:To analyze the combustion characteristics of diesel fuel in a CO2/O2 atmosphere, optical constant volume combustion chamber tests were conducted to measure and capture the combustion processes under six different operating conditions. The resultant flame images were subject to post-processing using custom Python code, enabling the extraction of parameters including flame lift-off height, red-green ratio, average luminosity, correlation coefficient, area change rate, and overlap ratio. The findings indicate that, in both air and CO2/O2 atmospheres, the flame lift-off height and correlation initially increase, then decrease, before experiencing a subsequent increase throughout the combustion process. Conversely, the average luminosity demonstrates an initial increase followed by a decline. Specifically, in the air and 35% CO2 + 65% O2 atmospheres, the peak values of flame lift-off height were measured as 210.75 px and 138.89 px, respectively. During the flame development stage, the red-green ratio remains within the range of 0.8 to 1.2, while in the flame extinction stage, it decreases as the CO2 concentration decreases and the O2 concentration increases. Compared to combustion in air, the combustion of diesel fuel in a CO2/O2 atmosphere displays an elongated flame shape, heightened turbulence, reduced flame lift-off height, and diminished average luminosity.
