Fuel Preparation in the Cylinder of a Port-Injected, Spark Ignition Engine

Liquid fuel in the cylinder was found to be the primary cause of inhomogeneity in the fuel distribution and therefore a principal contributor to HC emission. Much more liquid enters the cylinder with open-valve injection than with closed-valve injection. For some conditions a significant amount of liquid wets a small region of the cylinder wall and the slow evaporation of this liquid causes a locally high fuel vapor concentration at the end of the compression stroke. Increasing intake air velocity reduces the rate of fuel accumulation in the intake port, the sizes of droplets passing into the cylinder, and the amount of wall impingement, providing a more uniform fuel distribution in the cylinder. In addition, inhomogeneities in the fuel distribution within the cylinder which are present during the intake event can be substantially reduced by the end of the compression stroke with in-cylinder swirl. Increasing engine speed from 200 to 1200 rpm was much less effective for enhancing mixing than was increased swirl. Finally, the injector spray quality was found to affect the droplet sizes passing into the cylinder only for an open-valve injection timing.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Mechanical Engineering

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2015

Author dc:creator

• Kelly-Zion, Peter Lynwood

Contributors dc:contributor

• Peters, James E.

• Engineering, Automotive

Language dc:language

eng

Identifier

(MiAaPQ)AAI9912288

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/83976