Extended CMC Model for Turbulent Spray Combustion in a Diesel Engine 2008-01-2411
This study presents an extended Conditional Moment Closure (CMC) model  for turbulent spray combustion of a diesel engine. A spatially integrated CMC equation involves multiple flame structures, evaporation source terms for mixture fraction variance and scaled conditional scalar dissipation rates (CSDR) and probability density functions (PDF). An independent transport equation is solved for each flame group with equal mass of sequentially injected and evaporated fuel group. The implementation strategy in KIVA is to determine mean scalar variables instead of mean reaction rates in terms of conditional flame structures and local PDF's. Simulation is performed to test the suggested CMC model for a heavy duty diesel engine with early injection timings. NOx chemistry  is combined with skeletal chemistry of n-heptane  while soot is modeled by both one equation model  and two equation model . Parametric investigation is performed with respect to EGR (Exhaust Gas Recirculation) and injection timing. Results show that pressure traces, NOx and soot emissions are in reasonable agreement with measurements in a wide range of EGR levels and injection timings.