Date of Award

2018

Publication Type

Doctoral Thesis

Degree Name

Ph.D.

Department

Mechanical, Automotive, and Materials Engineering

Keywords

combustion, engine, ignition

Supervisor

Ming Zheng

Rights

info:eu-repo/semantics/openAccess

Abstract

The primary objective of the research was to study the limitations of the conventional spark ignition architecture with respect to ultra-lean and dilute combustion and develop ignition technologies and strategies that can facilitate such combustion strategies. A range of strategies using conventional and modified ignition coil systems were used in combustion chamber and engine tests to understand the effectiveness of the energy delivery mechanisms and different energy profiles. At operating conditions where the conventional ignition strategies had difficulties in achieving adequate ignition stability, the use of enhanced energy levels with different energy profiles for the achievement of effective ignition under high dilution ratio engine operating conditions was found to be necessary. A novel multiple-site ignition system was developed. It has been demonstrated to effectively deliver of ignition energy and achieved higher tolerance for lean combustion and high-dilution modes of combustion.

A radio-frequency non-thermal plasma ignition system was developed to investigate its ability to address some of the deficiencies of the spark ignition architecture. Compared to the conventional spark ignition architecture, the ignition volume induced by the corona discharge was greater in size and its growth was less impeded with the absence of a close ground electrode. The rapid energization and discharge characteristics additionally offered a more flexible control path. The formation of multiple ignition sites was possible, although implementation of the system in the engine environment has proven to be a continuing challenge.

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