Authors: J.B. Heywood
Addresses: Director, Sloan Automotive Laboratory, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
Abstract: Three distinct factors control the combustion process in a spark-ignition engine: chamber geometry and plug location; the mean motion of the charge and its turbulence characteristics; and the combustion chemistry of the fuel-air mixture. Our current understanding of these interactions is now sufficient to provide a rational procedure for combustion chamber optimization. The goals of such a procedure are to achieve fast, stable and repeatable combustion, cycle-by-cycle, with high volumetric efficiency and minimum heat transfer to the combustion chamber walls. It is shown that the primary design objective should be the best feasible combustion chamber geometry, with good distribution of the fuel, air and EGR mixture. This provides the desired benefits, with no operating penalties. Then, if additional combustion stability is still required to absorb the high EGR rates or additional air required for emission control or efficiency gains, increased turbulence should be employed. However, use of excess turbulence results in reduced volumetric efficiency and higher than necessary heat transfer.
Keywords: combustion chamber design; emissions; fuel consumption; schlieren combustion photography; spark ignition engines; vehicle design; turbulence; heat transfer.
International Journal of Vehicle Design, 1984 Vol.5 No.3, pp.336 - 357
Published online: 25 May 2014 *Full-text access for editors Access for subscribers Purchase this article Comment on this article