The influence of charge stratification on the spectral signature of partially premixed combustion in a light-duty optical engine
KAUST DepartmentClean Combustion Research Center
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AbstractThe origin of light emission during low-temperature combustion in a light-duty IC engine is investigated by high-speed spectroscopy in both HCCI and PPC regimes. Chemiluminescence and thermal radiation are expected to be the dominant sources of light emission during combustion. A method has been developed to distinguish chemiluminescence from thermal radiation, and different chemiluminescing species could be identified. Different combustion modes and global equivalence ratios are analyzed in this manner. The results indicate that the spectral signature (270–540 nm range) of the combustion is highly dependent on the stratification level. A significant broadband chemiluminescence signal is detected and superimposed on all spectra. This broadband chemiluminescence signal can reach up to 100 percent of the total signal in HCCI combustion, while it drops to around 80 percent for stratified combustion (PPC). We show that this broadband signal can be used as a measure for the heat release rate. The broadband chemiluminescence did also correlate with the equivalence ratio quite well in both HCCI and PPC regimes, suggesting that the total emission in the spectral region of 330–400 nm can serve as a proxy of equivalence ratio and the rate of heat release. Regarding C2* chemiluminescence, we see two different chemical mechanisms for formation of C2* in the PPC regime: first during the early stage of combustion by the breakup of bigger molecules and the second during the late stage of combustion when soot particles are forming.
CitationNajafabadi MI, Egelmeers L, Somers B, Deen N, Johansson B, et al. (2017) The influence of charge stratification on the spectral signature of partially premixed combustion in a light-duty optical engine. Applied Physics B 123. Available: http://dx.doi.org/10.1007/s00340-017-6688-9.
SponsorsThe research leading to these results has received funding from the People Programme (Marie Curie Actions) of the European Union’s Seventh Framework Programme FP7/2007–2013/ under REA Grant Agreement No. 607214. The authors would like to acknowledge Shell Global Solutions for providing the Volvo D5 optical engine setup.
JournalApplied Physics B
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