Measurement of ignition delay time of jet fuels in shock tube for the development of the chemical kinetic mechanism

Reliable yet tractable kinetic mechanisms for real aviation fuels are essential for predictive simulations of advanced combustors, and this thesis develops an F-24–specific HyChem mechanism by combining new experiments in a high-pressure shock tube with regularization-constrained, data-driven optimization of lumped reaction rates. GC×GC compositional analysis, together with prior work on F-24 and Jet-A, is used to justify Jet-A HyChem as the base mechanism and to highlight the distinct character of alternative fuels such as ATJ and CycloSAF. The UIUC shock tube is re-instrumented with a tailored driver and an endwall pressure transducer, enabling robust measurement of both overall and first-stage ignition delays for F-24 at 5–20 bar down to ~650–700 K and providing comparative data for a cycloalkane-rich CycloSAF. A Covariance Matrix Adaptation Evolution Strategy (CMA-ES) is then employed to optimize selected Arrhenius parameters of the 16 lumped HyChem reactions using a multi-objective function that combines ignition-delay RMSE and L1/L2-type regularization, with tight parameter bounds to preserve physical plausibility. The optimized mechanisms correct the baseline underprediction of F-24 ignition delays in the negative-temperature-coefficient and low-temperature regimes while maintaining high-temperature performance, and identify a small subset of high- and low-temperature reactions that dominate the required adjustments. First-stage ignition delays are shown to be critical for constraining low-temperature QOOH-cycle reactions, and a staged strategy that first optimizes overall ignition delays and then refines only low-temperature reactions against first-stage data is demonstrated to reproduce fully coupled multi-objective results at reduced computational cost. Validation against independent laminar flame speed measurements and shock-tube species profiles confirms that the regularized mechanisms retain balanced fidelity across ignition, flame propagation, and intermediate chemistry, while revealing specific larger unsaturated and aromatic species that require new kinetic pathways, thereby establishing a practical framework for constructing robust, fuel-specific HyChem mechanisms for current and emerging aviation fuels.

Name thesis:degree_name

M.S.

Level thesis:degree_level

Thesis

Discipline thesis:degree_discipline

Aerospace Engineering

Grantor

University of Illinois Urbana-Champaign

Year dc:date

2025

Author dc:creator

• Yoon, Sungho

Contributors dc:contributor

• Lee, Tonghun

• Chemical Kinetics
• Shock Tube
• Ignition Delay
• First-Stage Igntion Delay
• HyChem
• F-24
• CMA-ES optimization
• Regularization

Statement dc:rights

• Copyright 2025 Sungho Yoon, Tonghun Lee

Language dc:language

en

Handle dc:identifier

https://hdl.handle.net/2142/132698

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/132698