Mechanical Engineering Ph.D. Defense

Abstract 

Internal combustion engines, while promising, present their own set of environmental challenges for the future of mobility. This dissertation presents a comprehensive analysis, spanning engine performance testing to spray-level examination, to introduce a high-efficiency fuel-agnostic engine concept through multiple injection strategy as a viable alternative for future mobility solutions.

The primary focus of this research is to comprehend the intricacies of the multiple injection strategy and its impact on spray development. This is achieved through a combination of engine experiments, rate of injection characterization, and sprays studies of multiple injection conducted in a constant volume combustion chamber (CVCC). First, the research takes a focused approach by investigating the multiple injection strategy's applicability for achieving isobaric combustion across various fuels, revealing that each fuel requires a specific multiple injection scheme to achieve wide range of engine load. The key finding is that isobaric combustion, facilitated by the multiple injection strategy, establishes a fuel-agnostic paradigm in high-pressure combustion. Remarkably, the gasoline fuel demonstrates the highest engine efficiency, approaching the optimal efficiency in the context of the isobaric combustion concept.

This dissertation employs dedicated test rigs to investigate the rate of injection for multiple injection patterns under both non-reactive and high-pressure reactive conditions, replicating engine-like conditions. Fuels with multiple injection strategies were analyzed to provide insight into the characteristics of high-pressure combustion of different fuels. The spray characteristics was analyzed in terms of ignition delays, mixing, spray-to-spray interactions, and flame lift-off length. A hydrogen jet study was explored to understand the injection aspect in terms of mixing in direct injection via conventional gasoline direct injectors. This approach is to complement the overall understanding of high-pressure injection related to gas injection for future mobility. 

Bio

Bassam is a Ph.D. candidate in the Mechanical Engineering program in the PSE division, at the Engine and Fuels Facility and Spray Lab, supervised by Prof. William L Roberts. He earned his B.Sc. from Taibah University in Saudi Arabia, participated in a one-year exchange program at Pennsylvania State University, and later pursued his M.Sc. degree at Northeastern University in Boston. His research interests include fuels, spray characterization, and high-pressure combustion.