Diesel engine emission levels are strictly regulated over the years. Meeting these emission regulations has always been a challenging job for diesel engine developers. Considering the cost problems and complexity of diesel engine after-treatment systems, in order to meet the soot and NOx emission levels, engineers had to come up with alternative design solutions. Since changing the combustion chamber design has always been a more cost effective and easily applied solution compared to complex diesel engine after-treatment devices, various chamber designs have been researched and tested by engineers. The geometrical shape of the combustion chamber is particularly significant in order to change the turbulent flow structures and in-cylinder flow velocities that would effect combustion efficiency and engine-out emissions. Two of the most widely used designs are re-entrant and stepped-lip chambers. The stepped-lip design in particular, has been widely investigated due to their function of promoting recirculating flow structures which enhances fuel-air mixing and resulting with lower soot emission levels. The objective of this research is to investigate the effect of stepped-lip combustion chamber design and to compare with conventional re-entrant combustion chamber design. A CFD model has been carried out for these two chamber designs in order to analyze the flow structures and vortex formation.
Anahtar Kelimeler: Diesel Engine, Combustion Chamber, Stepped Lip, CFD Analysis, Soot Emission