Effect of Injection Parameters on Auto-Ignition and Soot Formation in Diesel Sprays

A validation study of the numerical model of n-heptane spray combustion based on experimental constant-volume data [1] was done, by comparing auto-ignition delays for different pre - turbulence levels and initial temperatures, flame contours, and soot distributions under Diesel-like conditions.

The basic novelty of the methodology developed in [2] - [3] is the implementation of the partially stirred reactor (PaSR) model accounting for detailed chemistry / turbulence interactions. It is based on the assumption that the chemical processes proceed in two successive steps: micro mixing, simulated on a sub - grid scale, is followed by the reaction act. When the all Re number RNG k-ε or LES models are employed, the micro mixing time can be consistently defined giving the combustion model a “well-closed” form incorporated into the KIVA-3V code. The reduced but still detailed mechanism integrating the n-heptane oxidation chemistry with the kinetics of aromatics formation (61 species, including soot forming agents up to the third aromatic ring, A2R5, and NOx species, 252 reactions) was used in the simulations. The effect on injection parameter variations (injection duration, schedule, including split injection etc.) was given special attention.