Qirui Yang develops a model chain for the simulation of combustion and emissions of diesel engine with fully variable valve train (VVT) based on extensive 3D-CFD simulations, and experimental measurements on the engine test bench. The focus of the work is the development of a quasi-dimensional (QDM) flow model, which sets up a series of sub-models to describe phenomenologically the swirl, squish and axial charge motions as well as the shear-related turbulence production and dissipation. The QDM flow model is coupled with a QDM combustion model and a nitrogen oxides (NOx) / soot emission model. With the established model chain, VVT operating strategies of diesel engine can be developed and optimized as part of the simulation for specific engine performance parameters and the lowest NOx and soot emissions.
Author(s): Qirui Yang
Series: Wissenschaftliche Reihe Fahrzeugtechnik Universität Stuttgart
Publisher: Springer Vieweg
Year: 2021
Language: English
Pages: 180
City: Wiesbaden
Preface
Contents
Figures
Tables
Abbreviations
Symbols
Abstract
Kurzfassung
1 Introduction
1.1 Motivation and Objectives
1.2 Structure of this Work
2 Fundamentals and State of the Art
2.1 Variable Valve Train in Diesel Engines
2.1.1 Variable Intake Valve Closing
2.1.2 Second Exhaust Valve Lift for Internal EGR
2.1.3 Valve Phasing for Swirl
2.2 Diesel EngineWorking Process Calculation
2.2.1 Modeling Charge Motions and Turbulence
2.2.2 Modeling Combustion
3 Quasi-dimensional Charge Motion and Turbulence Model
3.1 Model Overview
3.2 Quasi-dimensional Charge Motion Model
3.2.1 Swirl Model
3.2.2 Squish Model
3.3 Quasi-dimensional Turbulence Model
3.3.1 Turbulence Production
3.3.2 Turbulence Dissipation
3.4 Model Validation
3.4.1 Valve Actuation Variants
3.4.2 Operating Point Variants
3.4.3 Piston Configuratio Variants
3.4.4 Cylinder Dimension Variants
3.4.5 Deviation Analysis
3.5 Model Application
4 Coupling with Combustion Model
4.1 Overview of the Combustion Model
4.2 Pressure Trace Analysis and Model Calibration
4.3 Model Coupling
4.3.1 Implementation Turbulence
4.3.2 Implementation Swirl
4.4 Model Validation
4.4.1 Conventional Valve Train
4.4.2 Variable Valve Train
4.4.3 Deviation Analysis
5 Coupling with Emission Model
5.1 Overview of the Emission Model
5.2 Model Coupling
5.2.1 Implementation Turbulence
5.2.2 Implementation Swirl
5.3 Model Validation
5.3.1 Conventional Valve Train
5.3.2 Variable Valve Train
5.3.3 Deviation Analysis
6 Conclusion and Outlook
Bibliography
Appendix
A.1 Stand-alone Use of Swirl Model based on Linear Velocity
Profile
A.2 Block Diagram of QDM Flow Model
A.3 Variant Case without Swirl
A.4 Sensitivity Study on Model Parameters of QDM Flow
Model
A.5 Pressure Trace Analysis
