Numerical Evaluation of Soot Formation Control at Diesel-Like Conditions by Reducing Fuel Injection Timing

It has been found in the experiments [1], that fuel injection timings, ignition delays, and, thus, the mixture composition at the moment of auto-ignition had a considerable impact on soot formation in a constant volume at Diesel-like conditions. At increased ambient temperatures, soot formation started earlier and higher soot mass concentrations were registered during combustion. Increasing air pressures lead to a slight increase of the mass of soot formed. Nearly no difference of the maximum soot mass concentration has been observed, albeit the time period, in which soot was detected at a certain position increases with the ambient pressure increase. As observed in more resent experiments [2], a variation of the injected fuel quantity has been in an evident fashion related with the amount of soot produced with an exception that less soot yield has been confirmed when the injection time was simultaneously reduced. All these experimental observations are perfectly reproduced when the chemical mechanism integrating the reduced n-heptane oxidation chemistry with the detailed kinetics of aromatics (up to four aromatic rings) formation [3] has been used in the spray combustion simulations based on the KIVA-3 code.