Application of Two Sub-Models Relative to Chemical-Kinetics-Based Turbulent Pre-Mixed Combustion Modeling Approach on the Simulation of Burn Rate and Emissions of Spark Ignition Engines

摘要

This work presents an application of two sub-models relative to chemical-kinetics-based turbulent pre-mixed combustion modeling approach on the simulation of burn rate and emissions of spark ignition engines. In present paper, the justification of turbulent pre-mixed combustion modeling directly based on chemical kinetics plus a turbulence model is given briefly. Two sub-models relative to this kind of pre-mixed combustion modeling approach are described generally, including a practical PRF (primary reference fuel) chemical kinetic mechanism which can correctly capture the laminar flame speed under a wide range of Ford SI (spark ignition) engines/operating conditions, and an advanced spark plug ignition model which has been developed by Ford recently. Some validations of the two sub-models are presented in this paper, and steps to simulate the combustion process of gasoline engines have been presented, including the adaptive mesh refinement technique, grid resolution convergence investigation, and the method of multiple cycle simulation. Finally, applications of the two combustion sub-models to two typical operating conditions of a spark ignition engine have been carried out. The two engine operating conditions are a low load low speed WWMP (world wide mapping point) operating condition and a high load high speed warm-up operating condition. The simulated in-cylinder pressure, burn rate, and emissions including BSCO (brake specific carbon monoxide), NO_x and UHC (unburned hydro-carbon) were compared with experimental data, and good agreements were found.