Stochastic combustion modeling of direct injection diesel engines
A comprehensive diesel engine combustion model has been developed. The model is an extension of similar thermodynamic multi-zone models for gasoline engines. In this model, the charge is divided into many distinct zones to express geometric information and to provide spatial resolution. Within each zone structure, mass, momentum and energy conservations are expressed as lumped formulations. This basic structure is coupled with a stochastic treatment of the properties and processes related to turbulent mixing and transport. This description plays an essential part in the modeling of the inhomogeneity and the turbulent mixing. Besides the overall model development, the thesis improves the models for combustion product equilibrium composition and properties with an increased range of validity, which is crucial for diesel combustion simulations because of the wide local fuel-air ratio range. It also gives a robust solution procedure. A new coalescence/dispersion model for stochastic turbulent mixings is proposed. The new model provides a more realistic description of the initial phase of mixing which strongly affects burn rate predictions. Compressibility effects on turbulence are studied and significant improvements are made over the previous engine flow models. It is demonstrated that Reynolds stress models are needed to predict the non-equilibrium and anisotropic in-cylinder flows as they are subject to unsteady and nonisotropic compressions. The overall model is demonstrated to correlate well with experiments with respect to performance. Pressure trace and heat release are shown as functions of major operating conditions: inlet pressure and temperature, fuel-air ratio, EGR, fuel injection conditions, turbulence and swirl levels. NO{sub x} and soot emissions are predicted as functions of load, EGR, injection timing and turbulence level.
- Research Organization:
- Michigan Univ., Ann Arbor, MI (United States)
- OSTI ID:
- 6075863
- Resource Relation:
- Other Information: Thesis (Ph.D)
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
DIESEL ENGINES
COMBUSTION KINETICS
COMBUSTION PRODUCTS
COMPRESSION
EMISSION
EQUILIBRIUM
FLOW MODELS
FUEL INJECTION SYSTEMS
FUEL-AIR RATIO
MIXING
NITROGEN OXIDES
OPERATION
SOOT
STOCHASTIC PROCESSES
THERMODYNAMIC MODEL
TURBULENT FLOW
VORTEX FLOW
CHALCOGENIDES
CHEMICAL REACTION KINETICS
ENGINES
FLUID FLOW
FUEL SYSTEMS
HEAT ENGINES
INTERNAL COMBUSTION ENGINES
KINETICS
MATHEMATICAL MODELS
NITROGEN COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
PARTICLE MODELS
REACTION KINETICS
STATISTICAL MODELS
330102* - Internal Combustion Engines- Diesel