Computational modeling of Diesel spray combustion with multiple injections 2020-01-1155
Multiple injection strategies are commonly used in conventional Diesel engines due to the flexibility for optimizing heat-release timing with a consequent improvement in fuel economy and engine-out emissions, which is also desirable in low temperature combustion (LTC) engine since it offers the potential to reduce UHC and CO emissions. To better utilize these benefits and find optima calibrations of split strategies, it is imperative that the fundamental processes of multiple injection combustion are understood and CFD models accurately describe the flow dynamics and combustion characteristics between different injection events. To this end, this work is dedicated to the identification of suitable methodologies to predict the multiple injection combustion process. Two different approaches: Representative Interactive Flamelet model (RIF) employing different numbers of flamelets and Tabulated Flamelet Progress Variable (TFPV) are compared and Spray A conditions with multiple injections of Engine Combustion Network are simulated using the RANS methods with both standard k-ε and k-ω SST models. Evaluations of different turbulence and combustion models are carried out by comparing computed and measured data in terms of the mixing, penetration, first- and second-stage ignition characteristics, flame structures and soot formation.