Attenuation of combustion instability in a fuel-staged dual-nozzle gas turbine combustor with asymmetric hydrogen composition |
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| Institution: | 1. Department of Aerospace Engineering, Seoul National University, Seoul, 08826, Republic of Korea;2. Department of Safety Engineering, Incheon National University, Incheon, 22012, Republic of Korea;3. Institute of Advanced Aerospace Technology, Seoul National University, Seoul, 08826, Republic of Korea;1. Department of Energy and Process Engineering, Norwegian University of Science and Technology, Trondheim N-7491, Norway;2. Key Lab of Education Ministry for Power Machinery and Engineering, School of Mechanical Engineering Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai, 200240, China;1. Department of Mechanical and Aerospace Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong;2. Guangdong–Hong Kong–Macao Joint Laboratory for Data-Driven Fluid Mechanics and Engineering Applications, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong;3. Department of Aerospace Engineering, Korea Advanced Institute of Science and Technology, 291 Daehak-ro, Yuseong-gu, Daejeon 34141, Republic of Korea;1. School of Mechanical and Aerospace Engineering, Seoul National University, Seoul, Republic of Korea;2. Institute of Advanced Aerospace Technology, Seoul National University, Seoul, Republic of Korea;3. Clean Combustion Research Center, King Abdullah University of Science and Technology, Thuwal, Saudi Arabia;1. Department of Aerospace Engineering, Korea Advanced Institute of Science and Technology, 291 Daehak-ro, Yuseong-gu, Daejeon 34141, Republic of Korea;2. Department of Mechanical Engineering, Hanbat National University, 125 Dongseodae-ro, Yuseong-gu, Daejeon 34158, Republic of Korea |
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| Abstract: | The instability attenuation mechanism of fuel staging was investigated in a CH4/H2 fueled dual-nozzle gas turbine combustor. Fuel staging was implemented using an asymmetry in fuel composition between the two nozzles. The fuel composition of the upper nozzle was varied while keeping that of the lower nozzle constant. Under these conditions, the self-excited and forced responses of fuel-staged flames were analyzed using OH* chemiluminescence imaging, OH planar laser-induced fluorescence, and particle image velocimetry. In the self-excited measurements, although strong combustion instability was exhibited in the symmetric condition, it weakened gradually with increasing asymmetry in fuel composition. The symmetric flame exhibited significant fluctuations in the heat release rate around the flame tip, which acted as the primary cause of driving combustion instability. However, in asymmetric flames, the H2 addition induced phase leads in heat release rate fluctuations at the upper region, which damped combustion instability. Thus, our observations revealed a high correlation between the phase leads and the attenuation of combustion instability. Analyses of the forced responses showed that the heat release rate fluctuations were induced by interactions between the flame and the shedding vortex released from the nozzle tip into the downstream. Although these characteristics of shedding vortices did not depend on the H2 addition, the change in the axial position of the flame caused by the H2 addition induced the relocation of the site, at which the flame interacted with the vortex. Subsequently, it induced phase leads in the heat release rate fluctuations. The phase difference of heat release rate fluctuations between the two flames due to this phase leads enlarged progressively with increasing asymmetry in fuel composition, leading to the attenuation of combustion instability in asymmetric conditions. |
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