Development of a shear layer ignition model for application to direct-injection diesel engines

A transient, one-dimensional spray shear layer ignition model has been form ulated to provide a methodology for predicting the autoignition period in d irect-injection, quiescent chamber diesel engines. This approach focuses on including the influence of key injection and thermodynamic parameters that affect this key diesel combustion phenomenon. In particular, these importa nt parameters include injection rare, mean spray angle, bulk in-cylinder in stantaneous temperature and pressure, and residual gas fraction from a ther modynamic point-of-view. The proposed shear layer model agreed fairly well with experimental autoignition data derived from indirectly measured engine bulk fuel burning rate profiles even though ignition is modeled only accor ding to a one-step Arrhenius-type reaction that accounts for both local she ar layer equivalence ratio and temperature. In particular, the proposed mod el exhibited improved predictive capability in comparison to published zero -dimensional diesel engine autoignition correlations that are typically emp loyed in bulk parameter, diesel engine performance simulation models. (C) 2 000 by The Combustion Institute.