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Thermo-Acoustic Coupling and Dynamic Response of a Premixed Methane-Air Flame


Palm, Steven Leslie (2017) Thermo-Acoustic Coupling and Dynamic Response of a Premixed Methane-Air Flame. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/Z9V12309.


The work herein generally applies to the problem of combustion instability. Combustion instabilities first arose in engineering practice in the 1940s when they were experienced during the development of solid and liquid propellant rocket engines. Later, similar problems arose in gas turbine combustors and afterburners. However, the earliest technical case of the phenomenon dates back to Rijke in 1859 with his "singing" tube.

The presented work focuses on the study of a simple, stagnation plane stabilized, laminar, flat-flame burner. In particular the dynamic response of the burner is examined under excitation by a driven acoustic field. After characterization of the burner’s operational range, the response of the system is measured from 20 Hz to nearly 2000 Hz over the span of operating parameters using an optically filtered PMT and lens combination. A library of the collected and reduced data is generated.

A deeper investigation of the burner dynamics at a given reference operating condition is performed using phase-resolved PLIF. Fluctuations in the spatial distributions of the LIF signals for several target species (OH, CH, CH2O) under acoustic forcing are measured. In addition, visualization of the unsteady reactant flow using precision acetone seeding and PLIF at 277 nm is performed. Subsequent cinematographic sequences are produced along with spatially resolved plots of the combustion response function and the forced Rayleigh index for numerous drive frequencies. A library of the collected and reduced data is assembled.

Analysis of the collected data reveals two principal mechanisms contributing to the unsteady response of the flame. Structure development in (and subsequent convention along) the unsteady shear layer of the laminar jet dominates the response at the outer reaches of the flame. The inner region of the flame is driven largely by the Helmholtz response of the burner nozzle cavity. These two operations mutually contribute to produce the general shape of the combustion response curve. Ultimately, the data is used to construct a simplified model for the combustion response function. The model is enhanced with two additional revisions guided by the improved understanding of the mechanisms involved.

The document ends with numerous appendices describing, in detail, the equipment used, much of which was fabricated specifically for this work. These appendices, in combination with information presented in the chapters, provide substantial detail regarding the experimental configuration and operating conditions. Great effort was made to provide the necessary information to allow replication of the experiments as well as to support future modeling endeavors as a validation dataset.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:Combustion Instability, Thermo-Acoustic Coupling, Premixed Flame, Rayleigh's Criterion, Rayleigh Index, Combustion Response, Laser Diagnostics, PLIF, Planar Laser Induced Fluorescence, Chemiluminescence
Degree Grantor:California Institute of Technology
Division:Engineering and Applied Science
Major Option:Aeronautics
Minor Option:Electrical Engineering
Awards:Donald Coles Prize in Aeronautics, 2017
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Culick, Fred E. C.
Thesis Committee:
  • Shepherd, Joseph E. (chair)
  • Culick, Fred E. C.
  • Gharib, Morteza
  • Blanquart, Guillaume
  • Yang, Vigor
Defense Date:8 May 2017
Record Number:CaltechTHESIS:11302017-214955280
Persistent URL:
Palm, Steven Leslie0000-0003-3095-0368
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:10574
Deposited By: Steven Leslie Palm
Deposited On:04 Dec 2017 19:22
Last Modified:26 Oct 2023 20:19

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