Author ORCID Identifier

https://orcid.org/0000-0002-1936-669X

Year of Publication

2020

Degree Name

Master of Science in Mechanical Engineering (MSME)

Document Type

Master's Thesis

College

Engineering

Department/School/Program

Mechanical Engineering

First Advisor

Dr. Michael Wayne Renfro

Abstract

Premixed staged combustion in gas turbine engines can reduce emissions by lowering peak flame temperatures but can also lead to different stability characteristics when compared to traditional combustors. High pressure ratio and subsequently high temperatures can lead to conditions suitable for both autoignition and premixed flame propagation in an environment where spatial fuel/air variations are present.

An experimental facility which issues a premixed jet into a coflowing vitiated mixture was studied to examine the stability behavior, resulting in a lifted flame. The effective ignition delay observed flame was much greater than homogeneous ignition delay calculations for the same conditions. It follows that the heterogeneous environment arising from the mixing between fuel/air jet and vitiated coflow significantly impacts the autoignition behavior.

A numerical simulation modeled with dimensions identical to that of the experimental facility calculated liftoff heights consistent with the experimental flame. Analysis of energy and species balances along streamlines passing through the stabilization region of the flame suggest both premixed and autoignition behavior play a role in its stabilization. Additionally, species concentrations that are typically used for markers for autoignition, such as CH2O, occur due to mixing with autoignition regions rather than being produced on the streamline itself.

Digital Object Identifier (DOI)

https://doi.org/10.13023/etd.2020.418

Funding Information

This research was funded by the Kentucky Science and Engineering Foundation under grant number KSEF-148-502-17-411 (2017-2018).

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