Efficient development and uncertainty propagation of aviation fuel chemical kinetic models

This work presents a comprehensive methodology for the rapid development of reduced chemical kinetic mechanisms for jet fuels, with a focus on sustainable aviation fuels (SAFs). The framework is designed to balance model accuracy, computational efficiency, and experimental requirements for quick development times and application in complex environments like computational fluid dynamics (CFD). The method uses experimental ignition delay data from a shock tube and a rapid compression machine as primary validation targets, which are then used for data-driven optimization of chemical kinetic mechanisms. To efficiently propagate and reduce model uncertainty, a hybrid response surface network and stochastic gradient descent ensemble (HRSN-SGDE) technique is developed, enabling the rapid generation and analysis of a large distribution of optimized mechanisms. An approach is then introduced to generate a base mechanism from fuel composition data and a detailed surrogate mechanism library, which estimates averaged molecular properties and pyrolysis products for a lumped fuel decomposition mechanism structure. The methodology is demonstrated on four diverse fuels, and the uncertainty is propagated through a series of simulation outputs, including ignition delay, flame speed, and species concentrations. Finally, this uncertainty is propagated into a diffusion flame simulation to show uncertainty effects in more complex environments. The results show that while ignition delay measurements effectively constrain the models to match global performance, significant uncertainty can persist in other outputs, such as species concentration profiles, highlighting key areas for future improvements to enhance the reliability of chemical kinetic models for next-generation aviation fuels.

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

• Wiersema, Paxton

Contributors dc:contributor

• Lee, Tonghun
• Mayhew, Eric
• Glumac, Nick
• Ansell, Phillip

• combustion, chemical kinetics, SAF

Statement dc:rights

• Copyright 2025 Paxton Wiersema

Language dc:language

en

Handle dc:identifier

https://hdl.handle.net/2142/132750

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/132750