Combustion modeling for diesel engine control design

This thesis deals at first with the development of a consistent mixing model for the interactive coupling (two-way-coupling) of a CFD code and a multi-zone code based on multiple zero-dimensional reactors. The interactive coupling allows for a computationally efficient modeling of HCCI or PCCI combustion, respectively. The physical domain in the CFD code is subdivided into multiple zones based on three phase variables (fuel mixture fraction, dilution, and total enthalpy). These phase variables are sufficient for the description of the thermodynamic state of each zone, assuming that each zone is at the same pressure. Each zone in the CFD code is represented by a corresponding one in the zero-dimensional code. The zero-dimensional code solves the chemistry for each zone, and the heat release is fed back into the CFD code. The difficulty in facing this kind of methodology is to keep the thermodynamic state of each zone consistent between the CFD code and the zero-dimensional code after the initialization of the zones in the multi-zone code has taken place. The thermodynamic state of each zone (and thereby the phase variables) changes in time due to mixing and source terms (e.g., vaporization of fuel, wall heat transfer). The focus of this work lies on a consistent description of the mixing between the zones in phase space in the zero-dimensional code, based on the solution of the CFD code. Two mixing models with different degrees of accuracy, complexity, and numerical effort are described. The most elaborate mixing model (and an appropriate treatment of the source terms) keeps the thermodynamic state of the zones in the CFD code and the zero-dimensional code identical. The models are applied to a test case of HCCI combustion in a gasoline single-cylinder research engine. Following from there, a simulation model for PCCI combustion is derived that can be used in closed-loop control development. For the high-pressure part of the engine cycle, the interactively coupled CFD-multi-zone approach is systematically reduced to a stand-alone multi-zone chemistry model. This multi-zone chemistry model is extended by a mean value model accounting for the gas exchange losses. The resulting model is capable of describing PCCI combustion with stationary exactness, and is at the same time very economic with respect to computational costs. The model is further extended by identified system dynamics influencing the stationary inputs. For this purpose, a Wiener model is set up that uses the stationary model as a nonlinear system representation. In this way, a dynamic nonlinear model for the representation of the controlled plant Diesel engine is created.

Grantor dc:publisher

Shaker

Year dc:date

2009

Author dc:creator

• Felsch, Christian

Contributors dc:contributor

• Peters, Norbert

• info:eu-repo/classification/ddc/620
• Dieselmotor
• Turbulente Verbrennung
• Numerische Strömungssimulation
• Prädiktive Regelung
• Ingenieurwissenschaften
• HCCI combustion
• PCCI combustion
• CFD
• combustion model reduction
• stand-alone multi-zone model
• closed-loop control

Statement dc:rights

• info:eu-repo/semantics/openAccess

Language dc:language

eng

Identifier

https://publications.rwth-aachen.de/search?p=id:%22RWTH-CONV-113863%22

OAI record oai:identifier

https://publications.rwth-aachen.de/oai2d?verb=GetRecord&metadataPrefix=oai_dc&identifier=oai%3Apublications.rwth-aachen.de%3A51584