TY - GEN
T1 - Combustion oscillation in gas turbine combustor for fuel mixture of hydrogen and natural gas
AU - Uemichi, Akane
AU - Kanetsuki, Ippei
AU - Kaneko, Shigehiko
N1 - Funding Information:
This work was supported by JSPS Grand-in-Aid for Scientific Research (B) KAKENHI Grant Number 26289053. The authors also thank Mr. Tatsuo Watanabe at the University of Tokyo for his support with the experiment.
Copyright:
Copyright 2017 Elsevier B.V., All rights reserved.
PY - 2017
Y1 - 2017
N2 - 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.
AB - 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.
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U2 - 10.1115/PVP2017-65692
DO - 10.1115/PVP2017-65692
M3 - Conference contribution
AN - SCOPUS:85034024091
T3 - American Society of Mechanical Engineers, Pressure Vessels and Piping Division (Publication) PVP
BT - Fluid-Structure Interaction
PB - American Society of Mechanical Engineers (ASME)
T2 - ASME 2017 Pressure Vessels and Piping Conference, PVP 2017
Y2 - 16 July 2017 through 20 July 2017
ER -