Date of Award

Summer 8-2023

Author's School

McKelvey School of Engineering

Author's Department

Mechanical Engineering & Materials Science

Degree Name

Master of Science (MS)

Degree Type



The aviation industry is known to be one of the major contributors to greenhouse gases accounting for 4.9% of the global greenhouse emissions. With the ever-increasing threat of climate change to the overall survival of the planet, the exploration of new technologies and alternative energy sources that minimize greenhouse gas emissions are of paramount importance. In this regard, the development of propulsion systems well suited for the performance and emissions requirements of future commercial aircraft plays a crucial role. This thesis investigates N+3 and N+4 technology-level propulsion systems that are proposed by NASA as possible propulsion systems for advanced single-aisle commercial aircraft. Numerical simulation is utilized to evaluate the performance and emissions associated with the engines. The simulation is performed on the software called NPSS which is a component-based object-oriented engine cycle analysis and simulation tool. Liquid hydrogen (LH2), liquefied natural gas (LNG), ammonia (NH3), and ammonia-borane (AB) are explored as alternative fuel sources alternative to conventional Jet-A fuel. The engine size is fixed using published reference data from NASA and a fixed core engine model is developed and validated against the results obtained from fundamental ix propulsion equations coded in MATLAB; good agreement is obtained (within ±8%) for variation in Thrust Specific Fuel Consumption (TSFC) with Bypass Ratio (BPR). After validation of the NPSS engine model, a BPR sensitivity study is performed and the result shows that there is a significant improvement in TSFC with increasing BPR. To reduce the effect of the undesirable consequence of increasing drag with BPR, it is crucial to find the optimal BPR level and The BPR sensitivity study presented in this thesis can be used as a starting point in sizing an engine during the design process. Although the emissions study presented in this paper uses indexes, having robust models that can accurately predict emissions associated with alternative fuels is essential for the acceleration of technology development and implementation. In the absence of experimental data, the results presented in this work can be used as a reference for future attempts to enhance the accuracy of the emissions estimation.


English (en)


Dr. Ramesh Agarwal

Committee Members

Dr. Swami Karunamoorthy Dr. Xianglin Li