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Numerical Modeling of Gas Turbine Combustor Utilizing One-Dimensional Acoustics

Caley, Thomas
http://orcid.org/0000-0003-3614-0411
http://rave.ohiolink.edu/etdc/view?acc_num=ucin1491562189178949

Abstract Details

2017, MS, University of Cincinnati, Engineering and Applied Science: Aerospace Engineering.
This study focuses on the numerical modeling of a gas turbine combustor set-up with known regions of thermoacoustic instability. The proposed model takes the form of a hybrid thermoacoustic network, with lumped elements representing boundary conditions and the flame, and 3-dimensional geometry volumes representing the geometry. The model is analyzed using a commercial 3-D finite element method (FEM) software, COMSOL Multiphysics. A great deal of literature is available covering thermoacoustic modeling, but much of it utilizes more computationally expensive techniques such as Large-Eddy Simulations, or relies on analytical modeling that is limited to specific test cases or proprietary software. The present study models the 3-D geometry of a high-pressure combustion chamber accurately, and uses the lumped elements of a thermoacoustic network to represent parts of the combustor system that can be experimentally tested under stable conditions, ensuring that the recorded acoustic responses can be attributed to that element alone. The numerical model has been tested against the experimental model with and without an experimentally-determined impedance boundary condition. Eigenfrequency studies are used to compare the frequency and growth rates (and from that, the thermoacoustic stability) of resonant modes in the combustor. The flame in the combustor is modeled with a flame transfer function that was determined from experimental testing using frequency forcing. The effect of flow rate on the impedance boundary condition is also examined experimentally and numerically to qualify the practice of modeling an orifice plate as an acoustically-closed boundary. Using the experimental flame transfer function and boundary conditions in the numerical model produced results that closely matched previous experimental tests in frequency, but not in stability characteristics. The lightweight nature of the numerical model means additional lumped elements can be easily added when experimental data is available, creating a more accurate model without noticeably increasing the complexity or computational time.
Jongguen Lee, Ph.D. (Committee Chair)
Kwanwoo Kim, Ph.D. (Committee Member)
Mark Turner, Sc.D. (Committee Member)
101 p.
Aerospace Materials
Combustion Dynamics; FEM; Thermoacoustics; Acoustics

Recommended Citations

Citations

  • Caley, T. (2017). Numerical Modeling of Gas Turbine Combustor Utilizing One-Dimensional Acoustics [Master's thesis, University of Cincinnati]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1491562189178949

    APA Style (7th edition)

  • Caley, Thomas. Numerical Modeling of Gas Turbine Combustor Utilizing One-Dimensional Acoustics. 2017. University of Cincinnati, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=ucin1491562189178949.

    MLA Style (8th edition)

  • Caley, Thomas. "Numerical Modeling of Gas Turbine Combustor Utilizing One-Dimensional Acoustics." Master's thesis, University of Cincinnati, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1491562189178949

    Chicago Manual of Style (17th edition)

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This open access ETD is published by University of Cincinnati and OhioLINK.