Skip to main content
main-content
Top

About this book

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.

Table of Contents

Frontmatter

Chapter 1. Introduction

Abstract
Diesel engine has been developed sustainably over the decades and will continue to play an important role in traffic and transportation. It is recognized as an indispensable segment for original equipment manufacturers (OEM) to fulfill the overall fleet consumption requirements. However, compliance with the increasingly strict emission regulations is becoming a growing challenge for engine engineers.
Qirui Yang

Chapter 2. Fundamentals and State of the Art

Abstract
Variable valve train offers additional flexibilities to enable optimized charge exchange and charge motions, which are of particular importance in improving combustion and reducing emissions. At the current state of research, the following promising VVT techniques are conceivable in diesel engines.
Qirui Yang

Chapter 3. Quasi-dimensional Charge Motion and Turbulence Model

Abstract
Valve control strategy exerts an impact on combustion and emission characteristics to a large extent through changed in-cylinder charge motions and turbulence intensity. Quite many zero/quasi-dimensional models have been proposed for the prediction of in-cylinder flow properties, as introduced in Section 2.2.1. However, these models are either targeted at gasoline engines or need further extensions to meet the latest application requirements in diesel engines, e.g., variable valve train. On these grounds, a quasi-dimensional (QDM) flow model is developed for the diesel engines with a fully variable valve train.
Qirui Yang

Chapter 4. Coupling with Combustion Model

Abstract
In order for the combustion model to receive the outputs from the QDM flow model, it is essential to find out the interfaces between these two models. For this purpose, an analytical description of the chosen combustion model is given in the first place, whereby the existing interfaces are discussed. Next, the referential heat release rates are derived from measurement data through a pressure trace analysis (PTA).
Qirui Yang

Chapter 5. Coupling with Emission Model

Abstract
Following the coupling of the QDM flow model with the combustion model, this chapter integrates the previous work into a phenomenological two-zone emission model for a combined calculation of nitrogen oxide and soot emissions in DI diesel engines [40]. Analogous to Chapter 4, an overview of the emission model is given at first for illuminating the existing interfaces between the QDM flow model and the emission model. After that, modifications are implemented in two aspects relating to turbulence and swirl. At last, the modified emission model is validated using the measurement data obtained in the scope of the FVV project [50].
Qirui Yang

Chapter 6. Conclusion and Outlook

Abstract
A simulation chain has been established in this work for studying the impact of VVT operation on diesel engine performance and exhaust emissions. The process consists of a quasi-dimensional (QDM) flow model, a phenomenological combustion model, and a two-zone emission model for a combined NO and soot calculation. The newly developed QDM flow model predicts in-cylinder charge motions and turbulence for a full engine cycle under consideration of fully variable valve actuation.
Qirui Yang

Backmatter

Additional information

Premium Partner

    Image Credits