Combustion Instability Analysis of Hydrogen Co-firing Gas Turbine Combustors
수소 혼소 가스터빈 연소기에서의 연소불안정 해석
- 주제(키워드) 도움말 Combustion instability , Hydrogen co-firing , Gas turbine combustor , Flame transfer function , Thermoacoustic network model , Pilot injection , Fuel staging , Can-annular system , Mode clustering
- 발행기관 강원대학교 일반대학원
- 지도교수 도움말 김대식
- 발행년도 2026
- 학위수여년월 2026. 6
- 학위명 박사
- 학과 및 전공 도움말 일반대학원 기계시스템공학과
- 세부분야 해당없음
- 실제URI http://www.dcollection.net/handler/kangnung/000000012462
- UCI I804:42001-000000012462
- 본문언어 영어
초록/요약 도움말
The decarbonization of the power sector has positioned hydrogen co-firing — the blending of hydrogen into existing natural-gas-fired gas turbines — as a key bridge technology, but it amplifies combustion instability, a self-excited coupling between unsteady heat release and the acoustic field, as a central technical barrier. Industrial can-annular gas turbine combustors are developed along a hierarchical flow that progresses from the single nozzle, through the multi-nozzle can, to the can-annular system, yet an integrated treatment spanning all three configurations within a unified analytical framework has been limited. This dissertation analyzes combustion instability across these three configurations using a one-dimensional thermoacoustic network model as the common framework. The model is formulated as a closed-loop system and applied in a single-input single-output form to the single-nozzle and multi-nozzle can combustors and in a multi-input multi-output form to the can-annular system. The single-nozzle and multi-nozzle can analyses draw on full-scale combustor experimental data and CFD results, while the can-annular analysis uses experimental data from a separate laboratory-scale rig. For the single-nozzle combustor, a full-scale combustor exhibits a 275 Hz longitudinal instability that emerges at hydrogen fractions of 40–50% and is suppressed at higher pilot ratios. The hydrogen fraction and pilot ratio are shown to jointly govern the instability through a common physical pathway — their combined influence on the flame length and the resulting time delay of the flame response. For the multi-nozzle can combustor, a 5-around-1 combustor sharing the same nozzle exhibits a 199 Hz longitudinal mode that responds interdependently to pilot injection and outer nozzle fuel staging. This interdependence is shown to arise from the combined effect of the two staging methods on the per-nozzle flame structures and their associated time delays, demonstrating that the two cannot be treated as independent control variables. For the can-annular system, cross-talk-induced mode clustering is analyzed in a rig in which only the number of cans is varied （N = 1, 2, 4, 5）. The multi-input multi-output model is validated against self-excited combustion instability data, and the cluster's dependence on the number of cans is shown to collapse onto a single unifying principle determined by the acoustic phase relationship between adjacent cans. Together, the three analyses trace the hierarchical development flow of can-annular hydrogen co-firing gas turbine combustors — from the single-nozzle combustor, through the multi-nozzle can, to the can-annular system — within one consistent low-order framework. This demonstrates that a single thermoacoustic network model can serve as a unified analytical tool spanning the entire development hierarchy, adapting to the dominant instability physics that emerges at each configuration.
more목차 도움말
Chapter 1. Introduction 1
1.1 Research background 1
1.1.1 Hydrogen gas turbines and co-firing challenges 1
1.1.2 Combustion instability 5
1.1.3 Gas turbine combustor configurations 12
1.1.4 Computational prediction approaches 16
1.2 Prior research 19
1.2.1 Single-nozzle combustor 20
1.2.2 Multi-nozzle can combustor 23
1.2.3 Can-annular system 25
1.3 Research objectives 27
Chapter 2. 1D network modeling 29
2.1 Motivation for the acoustic transfer function formulation 30
2.2 Acoustic field representation and notation 33
2.3 Single-combustor ATF 35
2.4 Multi-combustor ATF 38
Chapter 3. Single-nozzle combustor: hydrogen co-firing and pilot injection 41
3.1 Experimental data 43
3.1.1 Combustor configuration and operating conditions 43
3.1.2 Instability characteristics and flame structure 48
3.2 CFD analysis 51
3.2.1 Numerical setup 51
3.2.2 CFD results 55
3.3 1D thermoacoustic modeling 61
3.3.1 Flame transfer function modeling 61
3.3.2 Thermoacoustic model description 72
3.3.3 Modeling results 77
3.4 Summary 81
Chapter 4. Multi-nozzle can combustor: combined fuel staging 83
4.1 Experimental data 85
4.1.1 Combustor configuration and operating conditions 85
4.1.2 Instability characteristics 90
4.2 CFD analysis 92
4.2.1 Numerical setup 92
4.2.2 Flame structure analysis 94
4.3 Thermoacoustic analysis 97
4.3.1 Reduction of the MIMO system to SISO form 97
4.3.2 FTF modeling for the multi-nozzle can combustor 101
4.3.3 1D geometry simplification 106
4.3.4 Stability map analysis 109
4.4 Summary 113
Chapter 5. Can-annular system: cross-talk-induced mode clustering 115
5.1 Experimental data 117
5.1.1 Combustor configuration and operating conditions 117
5.1.2 Resonant frequencies and mode structures 120
5.2 1D acoustic model validation 125
5.3 Characteristics of mode clustering 130
5.3.1 Clustering mechanism 130
5.3.2 Bounded frequency range 133
5.3.3 Bloch wavenumber ordering 136
5.4 Summary 141
Chapter 6. Conclusion 143
References 146
