Access Type

Open Access Thesis

Date of Award

January 2015

Degree Type


Degree Name



Mechanical Engineering

First Advisor

Naeim Henein


This thesis is an investigation of ionization in a military, heavy-duty, diesel engine. Ionization is a phenomenon which occurs in both spark-ignited and diesel engines. During the reactions of combustion, charged molecules and electrons are produced. The current produced, ion current, from these charges can be measured. The measurement of ion current can serve as an in-cylinder diagnostic for closed-loop engine control strategies. In this work, a literature review was performed to survey previous work as it pertains to ionization in diesel engines. In addition, a detailed description and comparison of the HEUI injection system was made to HPCR. This was done to give a fundamental understanding of the characteristics of the injection system which was employed in the research engine. Lastly, an analysis of experimental data provides insight as to the relationship between ion current and key combustion parameters.