Turbulent Combustion Rate in a Spark Ignition Engine: Some Comparisons Between Model Predictions and Experiments

摘要

A computer simulation model of the combustion process in a spark ignition engine is being developed for the investigation of flow field effects. The model is based on a two zone (burned and unburned gases) thermodynamic analysis of the combustion process that includes axisymmetric mean flow, uniform turbulence, and heat transfer. The turbulence is described by an averaged K-epsilon model which gives the bulk values of the turbulent kinetic energy and the dissipation rate in both the burned and unburned zones. Three experimental diagnostics were used in the study: the initial conditions for turbulence intensity necessary for the model were determined by laser Doppler velocimetry measurements made under motored conditions; the flame shape and location were found by laser shadowgraph photography; cylinder pressure measurements were recorded for both the average engine performance over many cycles, and for each individual cycle in which a photograph was taken. Comparisons between measurements and model predictions are presented for variations in engine speed and ignition location. (ERA citation 08:010171)