A numerical study on transient soot evolution of spray A flames based on a parcel tracing methodology

Accurately controlling combustion and achieving cleaner emissions in compression ignition engines need a better understanding of soot evolution. In the present study, the transient characteristics of in-flame soot evolution of spray A within the engine combustion network are numerically investigated under high-temperature and high-pressure conditions using a parcel tracing methodology. A virtual parcel driven by the current flow field, recording the local information to understand the evolution of soot. A two-equation soot model has been implemented based on the OpenFOAM platform, coupling with a ∑ − Y Eulerian spray model, and unsteady flamelet progress variable combustion model. The computed results indicate good agreement with the experimental ones under studied conditions. Results show that oxygen concentration significantly affects the onset soot location, which occurs at some radial distance away from the spray axis under low oxygen conditions, while it aligns along the spray axis for high oxygenconditions. The peak soot location of quasi-steady flames is concentrated around an equivalence ratio region ( 2 < Φ < 2.2 ) regardless of operating conditions. The chemical source of soot production is dominated by surface growth rate after the traced parcels pass through flame liftoff length where the local temperature exceeds 1500 K.