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Title:Design, setup of an optically accessible internal combustion engine for study of gasoline direct injection combustion
Author(s):Donahue, Robert Michael
Advisor(s):Lee, Chia-fon F.
Department / Program:Mechanical Sci & Engineering
Discipline:Mechanical Engineering
Degree Granting Institution:University of Illinois at Urbana-Champaign
Subject(s):Gasoline direct injection
Optical engine
High-speed imaging
Mie scattering
Natural luminosity
Abstract:Gasoline direct injection (GDI) engines are becoming attractive options for automobiles. The precise control over fuel delivery increases the potential for better fuel efficiency and higher performance. In this study, a single-cylinder optically-accessible engine was built to visualize GDI combustion. The optical engine was originally designed and used as a compression ignition engine for study of diesel combustion, but was extensively modified for GDI. The cylinder head was modified to include a spark plug, and a new ignition system was designed. In addition, a lowered compression ratio, new piston geometry, and new fuel injector were employed. In the experiment, combustion of a 20 percent ethanol/80 percent pure 90-octane gasoline fuel blend was studied. Experiments were conducted at 1200 rpm, and intake air and fuel were independently controlled. A metal version of the optical piston was made, and preliminary tests were conducted using the metal configuration. From these tests, engine performance, stability, and emissions were measured. Following the metal engine testing, an optical study was performed. Using a high-speed camera at 12,000 frames per second, images of fuel injector spray as well as combustion were recorded. A 3-dimensional Mie scattering technique was used to image the interaction of the fuel spray with the piston and cylinder walls, and natural flame luminosity was used to capture combustion images. From the experiments, it was concluded that in this configuration, a double injection with a first injection timing of 180° BTDC and a 90 percent/10 percent first/second injection split gave the best results with respect to engine stability and emissions. The combustion and spray imaging paired with corresponding performance and emissions data provide a broad picture of GDI combustion characteristics.
Issue Date:2017-04-26
Rights Information:Copyright 2017 Robert M. Donahue
Date Available in IDEALS:2017-08-10
Date Deposited:2017-05

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