ORCID

0009-0000-1641-8186

Keywords

combustion, alternative fuels, well-stirred reactor, green fuels, gas turbine combustion, combustor set-up

Abstract

Ammonia’s (NH3) properties as a carbon-free hydrogen carrier, its phase characteristics, and its wide global infrastructure present a solid case as a potential surrogate for carbon-based aviation fuels. Delivering a zero-emission NH3-based engine requires careful integration and optimization of the combustor and thermal management systems, a process that requires high-fidelity chemical reacting models experimentally validated through the use of simplified combustors. This study investigates NH3 fundamental combustion characteristics at conditions relevant to aviation gas turbines using a newly constructed toroidal jet-stirred reactor (TJSR) facility. Lean blow-off (LBO) experiments were carried out for NH3 blends with H2. Experimental results show that H2 addition improves the LBO limit of NH3, increasing the LBO limit at a maximum of ΔΦ = 0.38, resulting in lower reactor temperatures and better stability. It is also observed that an increase in inlet temperature increases the LBO, but by a lesser margin (ΔΦ = 0.14). Simulations were conducted using state-of-the-art chemical kinetic mechanisms to understand the effects of H2 fraction, residence times, and pressure on the lean stability limits of NH3-H2 blends. It is observed that an increase in H2 and residence time widens the LBO limits of these blends, consistent with the experimental observation. Heat loss was quantified utilizing an energy balance, in which a heat loss trend was created as a function of inlet temperature for most of the blends. Multiple PSR simulations were performed using different chemical mechanisms. As expected, the adiabatic case shows a leaner LBO than that of the experiments. The heat loss corrected models overpredict the LBO for most of the conditions tested. The Stagni mechanism shows better agreement at lower NH3 fractions, where UCF shows improved results at higher percentages.

Completion Date

2026

Semester

Spring

Committee Chair

Vasu, Subith

Degree

Master of Science in Aerospace Engineering (M.S.A.E.)

College

College of Engineering and Computer Science

Department

Mechanical and Aerospace Engineering

Format

PDF

Document Type

Thesis

Identifier

DP0053282

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