Development of a zero-dimensional Diesel combustion model: Part 2: Analysis of the transient initial and final diffusion combustion phases

The objective of this work is the development of a zero-dimensional Diesel combustion model. After the development of a model based on the apparent combustion time for the central phase of the quasi-steady Diesel diffusion combustion [Appl. Therm. Eng. 23 (2003)], this second part describes the work of generalization of the model for the final and initial transient phases of the diffusion combustion. For this purpose, those transient phases are analyzed mainly on the basis of the results of CFD calculations for pulsed gas jets. The generalization for the final transient diffusion combustion phase is based on the analysis of the evolution of the turbulent effective viscosity dissipation at the end of the injection process. For the initial transient diffusion combustion phase the work is based on the analysis of the air/fuel mixture at the beginning of the injection process. The result is a zero-dimensional model capable of predicting the diffusion combustion in a Diesel engine. The validation of the proposed model has been performed on both a high speed Diesel engine and a heavy duty Diesel engine.