Pressure dynamics,self-ignition,and flame propagation of hydrogen jet discharged under high pressure |
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| Affiliation: | 1. College of Safety Science and Engineering, Nanjing Tech University, Nanjing, 210009, China;2. Jiangsu Key Laboratory of Urban and Industrial Safety, Nanjing Tech University, Nanjing, 210009, China;1. Joint Institute for High Temperatures of Russian Academy of Science, 125412, Moscow, Izhorskaya Str., 13, Build. 2, Russia;2. Bauman Moscow State Technical University, 105005, Moscow, 2nd Baumanskaya Str., 5, Russia;1. Warsaw University of Technology, Institute of Heat Engineering, Nowowiejska 21/25, 00-665, Warsaw, Poland;2. University of Warwick, School of Engineering, Coventry CV4 7AL, UK;1. State Key Laboratory of Fire Science, University of Science and Technology of China, Hefei 230026, PR China;2. Department of Aerospace Engineering, University of Maryland, College Park, MD 20742, USA;3. Institute of Fluid Science, Tohoku University, Sendai, Miyagi 980-8577, Japan;1. State Key Laboratory of Fire Science, University of Science and Technology of China, Hefei 230026, Anhui, People''s Republic of China;2. Department of Aerospace Engineering, University of Maryland, College Park, MD 20742, USA;3. School of Chemical Machinery, Dalian University of Technology, Dalian, Liaoning 116024, People''s Republic of China;1. JAXA''s Engineering Digital Innovation Center, Japan Aerospace Exploration Agency, 3-1-1 Yoshinodai, Chuuou, Sagamihara, Kanagawa 252-5210, Japan;2. School of Engineering, University of Tokyo, 2-11-16 Yayoi, Bunkyo, Tokyo 113-0032, Japan;3. Graduate School of Environment and Information Sciences, Yokohama National University, 79-7 Tokiwadai, Hodogaya, Yokohama, Kanagawa 240-8501, Japan |
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| Abstract: | The self-ignition of hydrogen released from a high-pressure tank using extension tubes (2200 mm) with different diameters was studied. The processes of flame transition at a nozzle and jet flame development were characterized using a high-speed camera. The results indicated that the intensity of a shockwave and the Mach number decay faster in a 10-mm-diameter tube than that in a 15-mm-diameter tube. The pressure in a 15-mm-diameter tube was weaker than that in the 10-mm-diameter tube at the initial stage; however, it became higher in the later stage. Spontaneous ignition was more likely to happen in a 15-mm-diameter tube. The formation of a stabilized flame at the tube exit and Mach disk were observed during the transition of the flame to a jet fire. The stabilized flame showed a triangular shape because of the influence of a Prandtl–Meyer flow when a hydrogen jet entered a suddenly expanding environment. The formation and separation of a spherical flame were recorded during jet flame development. Large vortexes were formed in front of the flame because of the Kelvin–Helmholtz instability, which resulted in the separation of the spherical flame. The vortexes stopped rotating until the separated flame disappeared. |
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| Keywords: | Self-ignition Hydrogen Shockwave Transition Jet flame |
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