Mechanism of combustion instability due to flame-vortex interactions in a Lean Premixed gas turbine combustor

Hyung Ju Lee, Jong Guen Lee, Bryan D. Quay, Domenic A. Santavicca

    Research output: Chapter in Book/Report/Conference proceedingConference contribution

    Abstract

    An experimental study was conducted to identify a mechanism of combustion instability due to flame-vortex interactions and to characterize the effects of the interaction on self-excited unstable combustion in a swirl-stabilized lean-premixed gas turbine combustor. A variable-length combustor was designed to determine the preferred instability frequency at a given operating condition, and natural gas fuel was injected far upstream of the choked inlet to the mixing section to eliminate the possibility of equivalence ratio fluctuations. Experiments were performed over a broad range of operating conditions to simultaneously measure dynamic pressures in the combustor and mixing section and the overall rate of heat release. Acoustic velocity at the combustor inlet was obtained by the two-microphone technique, and two-dimensional CH* chemiluminescence flame images were taken to visualize stable and unstable flame structures and vortex dynamics during unstable combustion. The normalized heat release response versus the velocity fluctuation of the self-excited flames showed two regimes of response characteristics-linear and non-linear-which was analogous to forced flame responses. The phase synchronized CH* chemiluminescence images revealed flame-vortex interaction regardless of the instability modes or operating conditions for strong instability. Detailed modeshapes of the characteristic instability modes were investigated by thermoacoustic modeling, and verified with the extensive dynamic pressure measurements along the wall of the mixing section. Two distinct instability characteristics were observed as 1L mode at around 220 Hz and 2L mode near 350 Hz. It was deduced that the 1L mode instability was caused by the flame's active response to a perturbation at the frequency near 220 Hz, and the 2L mode instability was amplified by the system's gain related to the acoustics of the mixing section.

    Original languageEnglish (US)
    Title of host publication49th AIAA/ASME/SAE/ASEE Joint PropulsionConference
    StatePublished - Sep 16 2013
    Event49th AIAA/ASME/SAE/ASEE Joint PropulsionConference - San Jose, CA, United States
    Duration: Jul 14 2013Jul 17 2013

    Publication series

    Name49th AIAA/ASME/SAE/ASEE Joint Propulsion Conference

    Other

    Other49th AIAA/ASME/SAE/ASEE Joint PropulsionConference
    CountryUnited States
    CitySan Jose, CA
    Period7/14/137/17/13

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    All Science Journal Classification (ASJC) codes

    • Aerospace Engineering
    • Control and Systems Engineering
    • Electrical and Electronic Engineering

    Cite this

    Lee, H. J., Lee, J. G., Quay, B. D., & Santavicca, D. A. (2013). Mechanism of combustion instability due to flame-vortex interactions in a Lean Premixed gas turbine combustor. In 49th AIAA/ASME/SAE/ASEE Joint PropulsionConference (49th AIAA/ASME/SAE/ASEE Joint Propulsion Conference).