Title page for ETD etd-03102001-114618


Type of Document Master's Thesis
Author Nord, Lars
Author's Email Address lars.nord@comcast.net
URN etd-03102001-114618
Title A Thermoacoustic Characterization of a Rijke-type Tube Combustor
Degree Master of Science
Department Mechanical Engineering
Advisory Committee
Advisor Name Title
Saunders, William R. Committee Chair
Vandsburger, Uri Committee Co-Chair
Burdisso, Ricardo A. Committee Member
Keywords
  • flame instabilities
  • combustion
  • chemiluminescence
  • acoustics
Date of Defense 2001-02-21
Availability unrestricted
Abstract
Pressure pulsations, or thermoacoustic instabilities, as they are called in the research community, can cause extensive damage in gas turbine combustion chambers. To understand the phenomena related to thermoacoustics, a simple Rijke-type tube combustor was built and studied. Extensive experimental results, as well as theoretical analyses related to the Rijke tube are presented in this thesis. The results, attributable to both the analyses and the experiments, help explain all the phenomena affecting the acoustic pressure in the combustor. The conclusion is that there are three separate yet related physical processes affecting the acoustic pressure in the tube. The three mechanisms are as follows: a main thermoacoustic instability in accordance to the Rayleigh Criterion; a vibrating flame instability where the flame sheet exhibits mode shapes; and a pulsating flame instability driven by heat losses to the flame stabilizer. All these instabilities affect the heat released to the gas in the combustor. The energy from the oscillating heat couples with the acoustics of the volume bounded by the tube structure. The experimental results in the study are important in order to obtain model parameters for prediction as well as for achieving control of the instabilities.
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