CFD modelling study of sprays and combustion of gasoline and DMF in direct injection gasoline engines

• Main Author: Li, Haiying
• Published: University of Birmingham 2013
• Subjects: 621; TJ Mechanical engineering and machinery
• Online Access: https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.583089

The new biofuel candidate, 2, 5-Dimethylfuran (DMF) has received increasing interest as a potential alternative to fossil fuels, owing to the recent development of its new production technology. However, the effect of DMF properties on the fuel spray and vaporization, subsequent combustion processes and emission formation in the current Gasoline Direct Injection (GDI) engine is still not well understood. To investigate spray and combustion characteristics of DMF and explore possible applications to the IC engines, a three-dimensional Computational Fluid Dynamics (CFD) model has been developed using the KIVA3V code with improved spray models (nozzle flow model, spray atomization and secondary breakup models) and combustion models. This CFD model was validated by the optical diagnostics and then applied to study the in-cylinder mixture preparation and combustion characteristics of DMF in a GDI engine. The mixture preparation analysis shows both insufficient mixing time and significant spray-wall interaction when DMF is used result in relatively poor air/fuel distributions. Compared to the nearly homogeneous mixture with the gasoline fuel spray, a very rich fuel-air mixture of 7.7% and extremely lean mixture of 4.7% of the total charge has been observed in the case of DMF at the end of compression stoke. The analysis of combustion characteristics compared with the case of gasoline show that slightly longer combustion duration of DMF results from its lower laminar flame speed. The higher anti-knocking quality of DMF makes more advanced spark timing possible which brings about higher peak pressure and temperature and higher IMEP.