Combustion oscillation in gas turbine combustor for fuel mixture of hydrogen and natural gas

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

Abstract

Hydrogen as one of energy sources is attracting attentions because of CO2 free combustion that can deaccelerate global warming. Recently, hydrogen enriched combustion technology for gas turbine combustors is developing, in which hydrogen is added to natural gas. However, hydrogen-rich combustion has different combustion characteristics from conventional natural gas combustion. In particular, such variety of combustion characteristics may lead to combustion oscillation, which may cause fatigue breaking of structural elements due to resonance with components. Combustion oscillation is mainly induced by thermo-acoustics interaction. Therefore, it is necessary to investigate characteristics of hydrogen-enriched combustion sufficiently. To understand combustion characteristics of enriched hydrogen mixture, combustion experiments were performed for various ratios of hydrogen in the fuel mixture. In this study, a mock-up combustor of a micro gas turbine combustor is used, where a radial swirler is installed to mix fuel and air and stabilize the flame. To grasp the characteristics of combustion oscillation, pressure fluctuation was detected by a pressure sensor installed at the bottom of the combustor. It is found that larger hydrogen ratio in the fuel mixture extends the range of large pressure fluctuation region expressed by the root-mean-square value. Succeedingly, more detail oscillation characteristics were examined by FFT analysis. In the case of natural gas 100%, the oscillation of around 350 Hz was detected. On the other hand, in the case of the hydrogen-contained fuel mixture, two kinds of oscillating frequencies around 200 and 400 Hz were detected. To examine the cause of the difference among these three oscillating frequencies, a simplified stepped tube model with closed- and open-end is considered. For further investigation, acoustic boundary conditions were measured by acoustic impedance method. Moreover, to obtain the representative flame positions and temperature in the combustor, CFD calculations were performed, and the measured acoustic impedance was combined with the CFD results. Then, parametric studies with various thermo-pressure interaction index were performed to obtain the effect of thermo-pressure interaction index on natural frequencies and gains using the Nyquist plot. As a result, it was found that the self-excited oscillation limit is sensitive to the value of thermo-pressure interaction index.

Original languageEnglish
Title of host publicationFluid-Structure Interaction
PublisherAmerican Society of Mechanical Engineers (ASME)
ISBN (Electronic)9780791857977
DOIs
Publication statusPublished - 2017 Jan 1
Externally publishedYes
EventASME 2017 Pressure Vessels and Piping Conference, PVP 2017 - Waikoloa, United States
Duration: 2017 Jul 162017 Jul 20

Publication series

NameAmerican Society of Mechanical Engineers, Pressure Vessels and Piping Division (Publication) PVP
Volume4
ISSN (Print)0277-027X

Other

OtherASME 2017 Pressure Vessels and Piping Conference, PVP 2017
CountryUnited States
CityWaikoloa
Period17/7/1617/7/20

ASJC Scopus subject areas

  • Mechanical Engineering

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  • Cite this

    Uemichi, A., Kanetsuki, I., & Kaneko, S. (2017). Combustion oscillation in gas turbine combustor for fuel mixture of hydrogen and natural gas. In Fluid-Structure Interaction (American Society of Mechanical Engineers, Pressure Vessels and Piping Division (Publication) PVP; Vol. 4). American Society of Mechanical Engineers (ASME). https://doi.org/10.1115/PVP2017-65692