Pilot injection ignition delay sensitivity analysis for energy-assisted compression-ignition operation on jet fuels with varying cetane number
2022-01-0533
03/29/2022
- Event
- Content
- Local deposition of thermal energy can be used to assist the combustion process of low cetane number fuels in compression ignition engines, here termed energy-assisted compression ignition (EACI). In the current work, a commercial ceramic glow plug, operated beyond its conventional operation range, was used as the ignition assistant (IA) and sensitivity of pilot injection ignition to operation parameters was studied for two fuels using EACI in an optical engine. A design of experiments (DoE) study was devised to determine which engine parameters influenced the energy-assisted pilot injection ignition process the most. The DoE was constructed with four parameters: injection pressure, injected mass, injection timing, and IA temperature. The fuels used were F24 (Jet-A with military additives) with a cetane number (CN) of 48 and a CN 35 fuel mixture consisting of 60% F24 and 40% of an alcohol to jet fuel (ATJ), blended on a volumetric basis. Simultaneous OH chemiluminescence and schlieren imaging were employed along with in-cylinder pressure measurements to assess ignition delay, jet development, and the combustion process. A Gaussian active dimension hybrid emulator was employed to perform the sensitivity analysis. The results indicated that ignition of the fuel plume adjacent to the IA is mainly driven by the IA temperature, with over 90% of the sensitivity for both fuels. However, for IA surface temperatures greater than approximately 1300 K ignition delay is approximately constant with increasing temperature and the sensitivity to IA temperature decreases. This indicates the IA does not have to reach extremely high temperatures to assist or promote ignition on the plume of interest. A more detailed analysis is still required to determine if ignition of one plume can promote ignition of the remainder of the plumes and achieve complete combustion.
- Citation
- Amezcua, E., Kim, K., Rothamer, D., and Kweon, C., "Pilot injection ignition delay sensitivity analysis for energy-assisted compression-ignition operation on jet fuels with varying cetane number," SAE Technical Paper 2022-01-0533, 2022, .