Abstract
Keywords
Engine, Engine Combustion, Diesel Engine, Fumigation, Ignition, Chemical Kinetics
Abstract
A computation with a detailed chemical-kinetics mechanism was carried out to estimate, when a set of products from the low-temperature oxidation of premixed fuel is mixed with fresh fuel, how the products affect the low-temperature oxidation and ignition of the fresh fuel. A set of the products from a 'pre-cool-flame reaction' just before the cool-flame reaction promotes the ignition most effectively. Another set of the products after the cool-flame reaction promotes the ignition but not effectively, because it prolongs a period so called τ2. In this case the cool-flame reaction of the fresh fuel is terminated at a lower temperature than those in cases that τ2 is shorter. Then, a reaction loop starting with the production of OH from H2O via the production of HCO and HO2 to the reproduction of H2O2 has to drive itself at the lower temperature toward the ignition. This is caused mainly by a temperature rise with the cool-flame reaction of the premixed fuel, not by the products from the cool-flame reaction.