Effects of Cylinder Head Geometry on Mixture Stratification, Combustion and Emissions in A GDI Engine – A CFD Analysis 2019-01-0009
Preparation of air-fuel mixture in a GDI engine working in stratified conditions plays the key role to determine the combustion and emission characteristics. At most of the operating conditions, mixture stratification is required in these engines. The mixture stratification is mainly influenced by the in-cylinder flow structure and fuel injection parameters. However, in-cylinder flows thus, relies upon intake port configuration, Cylinder head and piston profile, engine speed etc. However, in-cylinder flows have an extensive bearing on combustion and emission characteristics of the engine. Therefore, in the present analysis, authors have attempted to comprehend the effect of cylinder head geometry on the mixture stratification, combustion and emission characteristics of a GDI engine. The CFD analysis is carried out on a single-cylinder, naturally-aspirated four-stroke GDI engine having a pentroof shaped cylinder head. The analysis is carried out at four pentroof angles (PA) viz., 8 degrees (base case), 14 degrees, 20 degrees and 25 degrees with the axis of the cylinder. The entire CFD simulations are performed at the engine speed of 2000 rev/min., and the overall equivalence ratio (ER) of 0.75. Finally, it is observed that the PA of 14 degrees produced about 10.5, 3 and 10.7% higher ITE, peak HRR, and NOx emissions respectively than that of the base case.
Om Prakash Saw, Srinivasa Krishna Addepalli, J M Mallikarjuna
Indian Institute of Technology Madras
International Powertrains, Fuels & Lubricants Meeting