Experiment on the autoignition characteristics of hydrogen and acetylene jets in a turbulent hot coflow
LIU Guijun1, LIU Jiayue2, ZHANG Yang1, WU Yuxin1
1. Key Laboratory for Thermal Science and Power Engineering of Ministry of Education, Department of Energy and Power Engineering, Tsinghua University, Beijing 100084, China; 2. School of Energy and Power Engineering, Dalian University of Technology, Dalian 116000, China
Abstract：[Objective] Hydrogen fuel gas turbine is the key equipment for large-scale hydrogen fuel power generation toward realizing the goal of carbon neutrality. Lean premixed combustion is an important technology for reducing the NOx emissions of modern gas turbines. However, compared with those of traditional hydrocarbon fuels, the high flame-propagation speed, wide flammability limit, and extremely low ignition energy of hydrogen increase the risk of autoignition and flashback in the premixed duct. Besides, the high mass-diffusion rate and flame-propagation speed of hydrogen in the sequential combustor with the second (reheat) stage of autoignition-stabilized flame render the flame stabilization mechanism is different from that of traditional hydrocarbon fuels. This study aims to understand the difference between hydrogen and acetylene as a hydrocarbon fuel in turbulent hot coflow in terms of autoignition type, flame structure, and stabilization mechanism. [Methods] A jet-in-coflow burner is used to conduct autoignition experiments. Based on our previous studies, acetylene, as an important small-molecule hydrocarbon, is selected as a hydrocarbon fuel for comparison with hydrogen. The fuel jet is injected into the hot coflow air through the fuel injection tube installed at the center axis of the burner. After being heated via the electric preheater, the compressed air flowed into the quartz tube to form a turbulent hot coflow exceeding the fuel ignition temperature. The photographs and OH chemiluminescence images of autoignition are obtained using a digital camera and an intensified charge-coupled device camera. The liftoff height, defined as the distance between the fuel injector exit and flame base (autoignition location), is a crucial parameter determining autoignition characteristics that strongly correlates with the flame stabilization mechanism. A ruler is mounted parallel to the quartz tube as a reference to measure the average liftoff height by comparing the autoignition location with the ruler mark. [Results] The results showed that with decreasing fuel mole fraction or increasing fuel jet velocity, the autoignited flame type of hydrogen and acetylene changed from the attached flame to random spots. Compared with that of acetylene, the flame zone of hydrogen random spots with light red was more compact. For the OH chemiluminescence-based flame structure, which was affected by the high mass-diffusion rate and flame-propagation speed of hydrogen, the independent autoignition points of hydrogen were undetectable. The flame zone became a continuous region. The liftoff height of hydrogen random spots was less sensitive to the fuel jet velocity than that of acetylene. The volatility of the hydrogen random point location was weak. Moreover, based on the mixing-strain model in the previous study, we found that the acetylene flame was mainly stabilized via autoignition kinetics. However, autoignition kinetics and flame propagation jointly determined the flame stabilization of hydrogen. The correlation of the liftoff height of hydrogen further indicated that flame propagation played a key role in flame stabilization. [Conclusions] In conclusion, this study, through experiments, reveals the difference in autoignition characteristics between hydrogen and acetylene in turbulent hot coflow, demonstrates the importance of flame propagation in stabilizing the hydrogen-autoignited flame, and modifies the liftoff height prediction model.
刘贵军, 刘佳悦, 张扬, 吴玉新. 湍流热伴流中氢气与乙炔射流自着火实验[J]. 清华大学学报（自然科学版）, 2023, 63(4): 594-602.
LIU Guijun, LIU Jiayue, ZHANG Yang, WU Yuxin. Experiment on the autoignition characteristics of hydrogen and acetylene jets in a turbulent hot coflow. Journal of Tsinghua University(Science and Technology), 2023, 63(4): 594-602.
[1] TAAMALLAH S, VOGIATZAKI K, ALZAHRANI F M, et al. Fuel flexibility, stability and emissions in premixed hydrogen-rich gas turbine combustion:Technology, fundamentals, and numerical simulations[J]. Applied Energy, 2015, 154:1020-1047. [2] TANG C L, ZHANG Y J, HUANG Z H. Progress in combustion investigations of hydrogen enriched hydrocarbons[J]. Renewable and Sustainable Energy Reviews, 2014, 30:195-216. [3] 蒋洪德,任静,李雪英,等.重型燃气轮机现状与发展趋势[J].中国电机工程学报, 2014, 34(29):5096-5102. JIANG H D, REN J, LI X Y, et al. Status and development trend of the heavy duty gas turbine[J]. Proceedings of the CSEE, 2014, 34(29):5096-5102.(in Chinese) [4] 秦锋,秦亚迪,单彤文.碳中和背景下氢燃料燃气轮机技术现状及发展前景[J].广东电力, 2021, 34(10):10-17. QIN F, QIN Y D, SHAN T W. Technology status and development prospects of hydrogen fuel gas turbine under the background of carbon neutral[J]. Guangdong Electric Power, 2021, 34(10):10-17.(in Chinese) [5] 李苏辉,张归华,吴玉新.面向未来燃气轮机的先进燃烧技术综述[J].清华大学学报(自然科学版), 2021, 61(12):1423-1437. LI S H, ZHANG G H, WU Y X. Advanced combustion technologies for future gas turbines[J]. Journal of Tsinghua University (Science and Technology), 2021, 61(12):1423-1437.(in Chinese) [6] 刘昊杨,钱文凯,朱民,等.燃料射流与空气协流混合中的自点火预测研究[J].工程热物理学报, 2021, 42(3):788-794. LIU H Y, QIAN W K, ZHU M, et al. Prediction of the autoignition of a fuel jet in a confined turbulent hot coflow[J]. Journal of Engineering Thermophysics, 2021, 42(3):788-794.(in Chinese) [7] BOTHIEN M R, CIANI A, WOOD J P, et al. Toward decarbonized power generation with gas turbines by using sequential combustion for burning hydrogen[J]. Journal of Engineering for Gas Turbines and Power, 2019, 141(12):121013. [8] BERNADR L, GUENTHER V E. Combustion, flames and explosions of gases[M]. Holland:Elsevier, 2012. [9] PENNELL D A, BOTHIEN M R, CIANI A, et al. An introduction to the Ansaldo GT36 constant pressure sequential combustor[C]//ASME Turbo Expo 2017:Turbomachinery Technical Conference and Exposition. Charlotte, USA:ASME, 2017:431-440. [10] HU Y, KUROSE R. Large-eddy simulation of turbulent autoigniting hydrogen lifted jet flame with a multi-regime flamelet approach[J]. International Journal of Hydrogen Energy, 2019, 44(12):6313-6324. [11] JUNG K S, KIM S O, LU T F, et al. On the flame stabilization of turbulent lifted hydrogen jet flames in heated coflows near the autoignition limit:A comparative DNS study[J]. Combustion and Flame, 2021, 233:111584. [12] KALANTARI A, MCDONELL V. Boundary layer flashback of non-swirling premixed flames:Mechanisms, fundamental research, and recent advances[J]. Progress in Energy and Combustion Science, 2017, 61:249-292. [13] FOTACHE C G, KREUTZ T G, LAW C K. Ignition of hydrogen-enriched methane by heated air[J]. Combustion and Flame, 1997, 110(4):429-440. [14] KIDO H, NAKAHARA M, NAKASHIMA K, et al. Influence of local flame displacement velocity on turbulent burning velocity[J]. Proceedings of the Combustion Institute, 2002, 29(2):1855-1861. [15] PETERSEN E L, KALITAN D M, BARRETT A B, et al. New syngas/air ignition data at lower temperature and elevated pressure and comparison to current kinetics models[J]. Combustion and Flame, 2007, 149(1-2):244-247. [16] 张晓宇.合成气燃料点火及火焰稳定性的研究[D].北京:清华大学, 2014. ZHANG X Y. Research on ignition characteristics and flame stability of syngas fuels[D]. Beijing:Tsinghua University, 2014.(in Chinese) [17] FREDERICK D, CHEN J Y. Effects of differential diffusion on predicted autoignition delay times inspired by H2/N2 jet flames in a vitiated coflow using the linear eddy model[J]. Flow, Turbulence and Combustion, 2014, 93(2):283-304. [18] MARDANI A, TABEJAMAAT S. Effect of hydrogen on hydrogen-methane turbulent non-premixed flame under MILD condition[J]. International Journal of Hydrogen Energy, 2010, 35(20):11324-11331. [19] MENDEZ L D A, TUMMERS M J, ROEKAERTS D J E M. Effect of hydrogen on the stabilization mechanism of natural gas jet-in-hot-coflow flames[C]//Proceedings of the 6th European Combustion Meeting. Lund, Sweden:Scandinavian-Nordic Section Combustion Inst, 2013:1-4. [20] MENDEZ L D A, TUMMERS M J, VAN VEEN E H, et al. Effect of hydrogen addition on the structure of natural-gas jet-in-hot-coflow flames[J]. Proceedings of the Combustion Institute, 2015, 35(3):3557-3564. [21] LI S H, QIAN W K, LIU H Y, et al. Autoignition and flame lift-off behavior of a fuel jet mixing with turbulent hot air coflow[J]. Proceedings of the Combustion Institute, 2021, 38(4):6385-6392. [22] LIU G J, LI S H. Lift-off height of autoignited jet flame in hot air coflow with different O2 contents[J]. Combustion and Flame, 2022, 242:112144. [23] OLDENHOF E, TUMMERS M J, VAN VEEN E H, et al. Ignition kernel formation and lift-off behaviour of jet-in-hot-coflow flames[J]. Combustion and Flame, 2010, 157(6):1167-1178. [24] CHOI B C, CHUNG S H. Autoignited laminar lifted flames of methane/hydrogen mixtures in heated coflow air[J]. Combustion and Flame, 2012, 159(4):1481-1488. [25] JUNG K S, KIM S O, LU T F, et al. Differential diffusion effect on the stabilization characteristics of autoignited laminar lifted methane/hydrogen jet flames in heated coflow air[J]. Combustion and Flame, 2018, 198:305-319. [26] CABRA R, MYHRVOLD T, CHEN J Y, et al. Simultaneous laser Raman-Rayleigh-LIF measurements and numerical modeling results of a lifted turbulent H2/N2 jet flame in a vitiated coflow[J]. Proceedings of the Combustion Institute, 2002, 29(2):1881-1888. [27] YOO C S, SANKARAN R, CHEN J H. Three-dimensional direct numerical simulation of a turbulent lifted hydrogen jet flame in heated coflow:Flame stabilization and structure[J]. Journal of Fluid Mechanics, 2009, 640:453-481. [28] LAWN C J. Lifted flames on fuel jets in co-flowing air[J]. Progress in Energy and Combustion Science, 2009, 35(1):1-30. [29] FLECK J M, GRIEBEL P, STEINBERG A M, et al. Auto-ignition and flame stabilization of hydrogen/natural gas/nitrogen jets in a vitiated cross-flow at elevated pressure[J]. International Journal of Hydrogen Energy, 2013, 38(36):16441-16452. [30] EITEL F, PAREJA J, JOHCHI A, et al. Temporal evolution of auto-ignition of ethylene and methane jets propagating into a turbulent hot air co-flow vitiated with NOx[J]. Combustion and Flame, 2017, 177:193-206. [31] GUPTA A, MARKIDES C N. Autoignition of an n-heptane jet in a confined turbulent hot coflow of air[J]. Experimental Thermal and Fluid Science, 2020, 119:110123. [32] MARKIDES C N, MASTORAKOS E. Experimental investigation of the effects of turbulence and mixing on autoignition chemistry[J]. Flow, Turbulence and Combustion, 2011, 86(3):585-608. [33] SCHEFER R W, KULATILAKA W D, PATTERSON B D, et al. Visible emission of hydrogen flames[J]. Combustion and Flame, 2009, 156(6):1234-1241. [34] GOLDMANN A, DINKELACKER F. Experimental investigation and modeling of boundary layer flashback for non-swirling premixed hydrogen/ammonia/air flames[J]. Combustion and Flame, 2021, 226:362-379. [35] SHEN X B, YANG X L, SANTNER J, et al. Experimental and kinetic studies of acetylene flames at elevated pressures[J]. Proceedings of the Combustion Institute, 2015, 35(1):721-728. [36] WU Z J, XIE W, ZHANG E B, et al. Investigation of flame characteristics of hydrogen jet issuing into a hot vitiated nitrogen/argon/carbon dioxide coflow[J]. International Journal of Hydrogen Energy, 2019, 44(52):28357-28370. [37] WU Z J, MASRI A R, BILGER R W. An experimental investigation of the turbulence structure of a lifted H2/N2 jet flame in a vitiated co-flow[J]. Flow, Turbulence and Combustion, 2006, 76(1):61-81. [38] CHOI B C, CHUNG S H. Autoignited laminar lifted flames of methane, ethylene, ethane, and n-butane jets in coflow air with elevated temperature[J]. Combustion and Flame, 2010, 157(12):2348-2356. [39] MASTORAKOS E, BARITAUD T A, POINSOT T J. Numerical simulations of autoignition in turbulent mixing flows[J]. Combustion and Flame, 1997, 109(1-2):198-223. [40] KERKEMEIER S G, MARKIDES C N, FROUZAKIS C E, et al. Direct numerical simulation of the autoignition of a hydrogen plume in a turbulent coflow of hot air[J]. Journal of Fluid Mechanics, 2013, 720:424-456. [41] LYONS K M. Toward an understanding of the stabilization mechanisms of lifted turbulent jet flames:Experiments[J]. Progress in Energy and Combustion Science, 2007, 33(2):211-231. [42] CABRA R, CHEN J Y, DIBBLE R W, et al. Lifted methane-air jet flames in a vitiated coflow[J]. Combustion and Flame, 2005, 143(4):491-506. [43] 邓俊,李理光,吴志军.协流温度对喷射起升火焰燃烧稳定性的影响[J].同济大学学报(自然科学版), 2013, 41(10):1567-1571. DENG J, LI L G, WU Z J. Effect of coflow temperature on combustion stabilization of jet flames[J]. Journal of Tongji University (Natural Science), 2013, 41(10):1567-1571.(in Chinese) [44] CHOI S K, CHUNG S H. Autoignited and non-autoignited lifted flames of pre-vaporized n-heptane in coflow jets at elevated temperatures[J]. Combustion and Flame, 2013, 160(9):1717-1724. [45] AL-NOMAN S M, CHOI B C, CHUNG S H. Autoignited lifted flames of dimethyl ether in heated coflow air[J]. Combustion and Flame, 2018, 195:75-83. [46] HERZLER J, NAUMANN C. Shock-tube study of the ignition of methane/ethane/hydrogen mixtures with hydrogen contents from 0% to 100% at different pressures[J]. Proceedings of the Combustion Institute, 2009, 32(1):213-220. [47] KOLB M, AHRENS D, HIRSCH C, et al. A model for predicting the lift-off height of premixed jets in vitiated cross flow[J]. Journal of Engineering for Gas Turbines and Power, 2016, 138(8):081901.
2023, Vol. 63 
