New Phenomenological Six-Zone Combustion Model for Direct-Injection Diesel Engines

Abstract

A new phenomenological multizone combustion model has been developed for direct-injection (DI) diesel engines based on the well-known Dec's "conceptual" model for DI diesel combustion as well as spray models from Siebers et al. (liquid- and vapor-phase fuel penetration, spray spreading angle, and lift-off length). The model distinguishes six zones and provides local information, such as mean equivalence ratio and temperature in the various zones. A validation of the model is performed while varying main engine parameters, such as engine speed and load, inlet air temperature, exhaust gas recirculation (EGR) rate, boost pressure, or the injection pressure. The model is able to calculate the rate of heat release (ROHR) with good accuracy, whereas the variation of calculated local parameters (core spray and flame temperature, lift-off length, and corresponding equivalence ratio) can be used to explain the main tendencies on engine-out NOx and particulate matter (PM) emissions observed on the engine test bench.