Design and analysis of a compact high-speed air-breathing engine

This dissertation investigates the underlying physics of challenges associated with compact, high-speed, air-breathing propulsion systems and examines potential solutions. The primary focus is on the unique technical challenges posed by the stringent requirement for a compact design, which will fundamentally alter system performance. Such propulsion systems are critical for the development of platforms such as the Air-Launched Effect (ALE)—a small, unmanned reconnaissance aircraft. To address these challenges, this study combines component design, theoretical analysis, high-speed wind tunnel experiments, and reduced-order modeling. Component-level analyses revealed critical design trade-offs. For the inlet, it was found that while scoop inlets offered high theoretical efficiency, truncated planar two-dimensional inlets provided superior performance for compact designs. For the combustor, experiments demonstrated that newly designed inserts, particularly mesh-based inserts, were capable of achieving stable and more compact combustion compared to a baseline configuration. For the exhaust nozzle, analysis showed that designing for under-expanded conditions enabled a remarkable 44 % length reduction with a corresponding thrust penalty of 20 %. Subsequently, these component-level findings were integrated into a reduced-order model. After its combustor sub-model was tuned and validated against the experimental data, the complete model was used to produce a preliminary integrated engine design, 1319.2 mm in length, capable of generating 137.8 N of thrust for the target flight condition. The primary contribution of this work is a complete design-and-analysis framework that provides critical insights into the performance of compact ramjet/scramjet components and delivers a validated tool for the rapid preliminary design of such propulsion systems.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Mechanical Engineering

Grantor

University of Illinois Urbana-Champaign

Year dc:date

2025

Author dc:creator

• Kato, Nozomu

Contributors dc:contributor

• Lee, Tonghun
• Mayhew, Eric K.
• Rovey, Joshua L
• Chamorro, Leonardo P.

• Scramjet
• Ramjet
• Air-breathing Engine
• Hypersonics

Statement dc:rights

• Copyright 2025 Nozomu Kato

Language dc:language

en, eng

Handle dc:identifier

https://hdl.handle.net/2142/130160

OAI record oai:identifier

https://www.ideals.illinois.edu/oai-pmh?verb=GetRecord&metadataPrefix=etdms&identifier=oai%3Awww.ideals.illinois.edu%3A2142%2F130160