The 2011 Byron Bird Award
In the early 1980s, Phil and Jean Myers Professor of Mechanical Engineering David Foster applied for a grant from the National Science Foundation to explore a type of combustion that a group of two-stroke engine researchers in Japan had stumbled across. He wanted to study the fundamental science behind this odd combustion, which he thought perhaps could be used to reduce emissions in the typical four-stroke engines used in vehicles. The grant reviewers turned down Foster’s proposal because what he was advocating seemed impossible.
Foster received the rejection letter the day after he and then-graduate student Paul Najt demonstrated in his lab that this type of combustion, called homogeneous charge compression ignition (HCCI), was in fact feasible in four-stroke engines. Their 1983 SAE paper, Compression-Ignited Homogeneous Charge Combustion, has ignited a slow revolution in engine research. Almost 30 years the later, the paper remains the most widely cited in HCCI R&D. “Professor Foster, through his keen insight into combustion chemistry, saw the potential for this anomalous model of combustion,” says a colleague.
Unlike spark-ignition engines, where combustion is ignited by a spark plug and proceeds as a propagating front, an HCCI engine is ignited by compressing a homogeneous mixture until it reaches a high temperature. The mixture then auto-ignites. Well-mixed, dilute fuel in an HCCI engine forms substantially less soot, carbon dioxide and nitrogen than traditional spark-ignition engines.
Foster and Najt’s paper explained, for the first time, the fundamentals behind HCCI that had been observed in two-stroke studies. They modeled the spontaneous-ignition process and performed carefully controlled four-stroke cycle engine experiments to identify the key engine design and operating variables involved in the process. They also determined the fuel composition requirements necessary to achieve HCCI combustion and indicated how these findings could be used to improve efficiency and emissions in standard engines.
HCCI research has taken off in the last decade as automotive makers seriously consider how to reduce emissions while at the same time increase fuel efficiency. Most, including General Motors, have already built and tested prototype HCCI engines and vehicles.
&8220;Professor Foster’s publication is widely recognized by both academic and industrial researchers as the seminal contribution that launched the HCCI combustion process into the forefront engine research,” say two of Foster’s Engine Research Center colleagues.
“Beyond being recognized as a stalwart publication, this work is now bearing real fruit in products that are entering the marketplace.”