氢气作为一种密度低、燃烧范围宽的可燃气体，泄漏后易与空气混合形成可燃性非均匀混合气体，在受限空间内，遇到点火源极易发生燃爆事故。本文将针对受限空间内氢气-空气非均匀混合气体的爆炸火焰传播特性展开研究。

利用Fluent软件，对氢气随扩散时间的运移过程进行数值研究。空间内氢气-空气随扩散时间的增加，由非均匀混合状态逐渐转变为均匀混合状态。氢气泄漏过程中，始终在空间中上部运动。扩散初期气体非均匀程度较高，上部氢气左右运动。扩散至60 s时，形成氢气分布在中上部，空气分布在下部的稳定状态。之后氢气在重力作用下逐渐向下方扩散，扩散至200 s左右时，空间内的氢气浓度趋向同一数值，约为1.2510^-2 kg/m³，气体混合相对均匀。

采用水平可视化管道系统，研究不同当量比（0.6、0.8、1.0、1.2、1.4、1.6、1.8），不同扩散时间（0 s、10 s、60 s、180s、300 s）条件下的氢气-空气爆炸压力和爆炸压力上升速率。结果表明当量比对爆炸压力的影响较大。当量比在1~1.8之间，压力震荡幅度较大，其中当量比为1.4时压力震荡幅度最大。当量比为0.6时，气体的扩散时间对可燃气的爆炸压力影响较大。当量比在0.6~1.2之间，湍流程度高且非均匀状态下的最大爆炸压力最大；当量比在1.4~1.8之间，气体湍流程度低且非均匀状态下的最大爆炸压力最大。非均匀混合气体能增强爆炸能量释放，但均匀混合气体爆炸强度相对较大，其中扩散时间为300 s时的爆炸强度最大，为45.11 MPam/s。

结合高速摄影仪，研究不同当量比、扩散时间下的氢气-空气混合气体爆炸火焰结构和爆炸火焰传播速度。结果表明气体扩散时间一定时，当量比越大，火焰表面褶皱越明显。当量比为1时的“郁金香”火焰结构最明显，且火焰亮度最大。同一当量比下，扩散时间为0 s、10 s（非均匀）比扩散时间为180 s、300 s（均匀）的火焰前锋褶皱多。低当量比时，火焰传播速度随扩散时间的减小而减小；高当量比时，火焰传播速度随扩散时间的增加而增大。非均匀氢气-空气火焰传播速度随着当量比的升高而不断减小，均匀气体的火焰传播速度随当量比的升高而不断增加。火焰传播速度最快出现在扩散时间为0s，当量比为1.2时，为125 m/s。

本文研究的成果以期为氢气-空气非均匀混合气体的爆炸火焰传播特性提供实验依据，为氢气工业化发展奠定坚实的安全基础。

As a combustible gas with low density and wide combustion range, hydrogen is easy to mix with air to form a non-uniform combustible mixture after leakage. In a confined space, it is easy to ignite and explode when encountering ignition sources. In this paper, the flame propagation characteristics of non-uniform mixtures of hydrogen and air in confined space are studied.

The migration process of hydrogen with diffusion time was numerically studied by using Fluent software. With the increase of diffusion time, the non-uniform mixing state of hydrogen and air in space gradually changes to uniform mixing state. During the process of hydrogen leakage, it always moves in the upper middle of the space. At the initial stage of diffusion, the gas is non-uniform and the upper hydrogen moves from side to side. When it diffuses to 60 s, it forms a stable state in which hydrogen is distributed in the middle and upper part and air is distributed in the lower part. After that, hydrogen gradually diffuses downward under the action of gravity, and when it diffuses to about 200 s, the hydrogen concentration in the space tends to the same value, about 1.2510-2 kg/m³, and the gas mixture is relatively uniform.

A horizontal visualization pipeline system was used to study the explosion pressure and explosion pressure rise rate of hydrogen-air under different equivalent ratios (0.6, 0.8, 1.0, 1.2, 1.4, 1.6, 1.8) and different diffusion times (0s, 10 s, 60 s, 180s, 300 s). The results show that the equivalent ratio has a great influence on the explosion pressure. When the equivalent ratio is between 1 and 1.8, the pressure oscillation range is large, and when the equivalent ratio is 1.4, the pressure oscillation range is the largest. When equivalent ratio is 0.6, the gas diffusion time has a great influence on the explosion pressure of combustible gas. When the equivalent ratio is between 0.6 and 1.2, the maximum explosion pressure is the largest under the condition of high turbulence and non-uniformity. The maximum explosion pressure is the highest when the equivalent ratio is between 1.4 and 1.8 and the gas turbulence is low and non-uniform. The non-uniform mixture can enhance the release of explosion energy, but the explosion intensity of the uniform mixture is relatively large, in which the explosion intensity of 45.11 MPam/s is the highest when the diffusion time is 300 s.

The flame structure and flame propagation velocity of hydrogen air mixture under different equivalent ratio and diffusion time were studied by high-speed camera. The results show that when the gas diffusion time is constant, the more equivalent ratio is, the more obvious the flame surface folds are. When the equivalent ratio is 1, the flame structure of "tulip" is the most obvious, and the flame brightness is the largest. Under the same equivalent ratio, there are more folds of flame front with diffusion time of 0 s and 10 s (non-uniform) than with diffusion time of 180 s and 300 s (uniform). When the equivalent ratio is low, the flame propagation velocity decreases with the decrease of diffusion time. When the equivalent ratio is high, the flame propagation velocity increases with the increase of diffusion time. The flame propagation velocity of non-uniform hydrogen-air decreases with the increase of equivalent ratio, while the flame propagation velocity of homogeneous gas increases with the increase of equivalent ratio. The fastest flame propagation speed is 125 m/s when the diffusion time is 0s and the equivalent ratio is 1.2.

The research results of this paper are expected to provide experimental basis for the explosion flame propagation characteristics of non-uniform mixture of hydrogen and air, and lay a solid safety foundation for the development of hydrogen industrialization.

[1] Arsad A, Hannan M, Al-Shetwi A, et al. Hydrogen energy storage integrated hybrid renewable energy systems: A review analysis for future research directions[J]. International Journal of Hydrogen Energy, 2022, 47(39): 17285-17312.

[2] 郑津洋, 刘自亮, 花争立, 等.氢安全研究现状及面临的挑战[J].安全与环境学报, 2020, 20(1): 106-115.

[3] Usman M R. Hydrogen storage methods: Review and current status[J]. Renewable and Sustainable Energy Reviews, 2022, 167: 112743.

[4] 徐硕, 余碧莹. 中国氢能技术发展现状与未来展望[J]. 北京理工大学学报(社会科学版), 2021, 23(6): 1-12

[5] Wang L, Hong C, Li X, et al. Review on blended hydrogen-fuel internal combustion engines: A case study for China[J]. Energy Reports, 2022, 8: 6480-6498.

[6] Liu W, Wan Y, Xiong Y, et al. Green hydrogen standard in China: Standard and evaluation of low-carbon hydrogen, clean hydrogen, and renewable hydrogen[J]. International Journal of Hydrogen Energy, 2022, 47(58): 24584-24591.

[7] Gao X, An R. Research on the coordinated development capacity of China's hydrogen energy industry chain[J]. Journal of Cleaner Production, 2022,377: 134177.

[8] Chau K, Djire A, Khan F. Review and analysis of the hydrogen production technologies from a safety perspective[J]. International Journal of Hydrogen Energy, 2022, 47(29): 13990-14007.

[9] Yang F, Wang T, Deng X, et al. Review on hydrogen safety issues: Incident statistics, hydrogen diffusion, and detonation process[J]. International journal of hydrogen energy, 2021, 46(61): 31467-31488.

[10]West M, Al-Douri A, Hartmann K, et al. Critical review and analysis of hydrogen safety data collection tools[J]. International Journal of Hydrogen Energy, 2022, 47(40): 17845- 178458.

[11]Sakamoto J, Sato R, Nakayama J, et al. Leakage-type-based analysis of accidents involving hydrogen fueling stations in Japan and USA[J]. International journal of hydrogen energy, 2016, 41(46): 21564-21570.

[12]Lacome J M, Jamois D, Perrette L, et al. Large-scale hydrogen release in an isothermal confined area[J]. International Journal of Hydrogen Energy, 2011, 36(3): 2302-2312.

[13]Stefano D M, Rocourt X, Sochet I, et al. Hydrogen dispersion in a closed environment[J]. International Journal of Hydrogen Energy, 2019, 44(17): 9031-9040.

[14]黄腾. 大型地下车库内氢气泄漏与扩散研究[D].山东: 山东大学, 2021.

[15]Tanaka T, Azuma T, Evans J A, et al. Experimental study on hydrogen explosions in a full-scale hydrogen filling station model[J]. International Journal of Hydrogen Energy, 2007, 32(13): 2162-2170.

[16]Cariteau B, Brinster J, Tkatschenko I. Experiments on the distribution of concentration due to buoyant gas low flow rate release in an enclosure,International Journal of Hydrogen Energy, 2011, 36(3): 2505-2512.

[17]Cariteau B, Tkatschenko I. Experimental study of the concentration build-up regimes in an enclosure without ventilation[J]. International Journal of Hydrogen Energy, 2012, 37(22): 17400-17408.

[18]李雪芳. 储氢系统意外氢气泄漏和扩散研究[D]. 北京: 清华大学, 2015.

[19]Shu Z Y, Liang W Q, Zheng X H, et al. Dispersion characteristics of hydrogen leakage: Comparing the prediction model with the experiment[J]. Energy, 2021, 236: 121420.

[20]卢明, 徐晔, 肖学章. 室内氢气泄漏扩散的数值模拟[J]. 中国安全生产科学技术, 2011, 7(8): 29-33.

[21]Swain M R, Filoso P, Grilliot E S, et al. Hydrogen leakage into simple geometric enclosures[J]. International journal of hydrogen energy, 2003, 28(2): 229-248.

[22]刘延雷. 高压氢气快充温升控制及泄漏扩散规律研究[D]. 浙江: 浙江大学, 2009.

[23]刘延雷, 秦永泉, 盛水平, 等. 燃料车内氢气泄漏扩散数值模拟研究[J]. 中国安全生产科学技术, 2009, 5(5): 5-8.

[24]Hussein H, Brennan S, Molkov V. Dispersion of hydrogen release in a naturally ventilated covered car park[J]. International Journal of Hydrogen Energy, 2020, 45(43): 23882-23897.

[25]戚雄飞, 侯丽强, 杜政瑀, 等. 单隔间内氢气流动分布特性数值模拟与实验验证[J]. 强激光与粒子束, 2020, 32(5): 124-129.

[26]李云浩, 喻源, 张庆武. 车库内氢气扩散和分布状态的数值模拟[J]. 安全与环境学报, 2017, 17(5): 1884-1889.

[27]Dai T, Zhang B, Liu H. On the explosion characteristics for central and end-wall ignition in hydrogen-air mixtures: A comparative study[J]. International Journal of Hydrogen Energy, 2021, 46(60): 30861-30869.

[28]Cao Y, Guo J, Hu K, et al. Effect of ignition location on external explosion in hydrogen– air explosion venting[J]. International Journal of Hydrogen Energy, 2017, 42(15): 10547- 10554.

[29]Wang L Q, Ma H H, Shen Z W. Effects of vessel height and ignition position upon explosion dynamics of hydrogen-air mixtures in vessels with low asymmetry ratios[J]. Fuel, 2021, 289: 119926.

[30]Zhang K, Luo T P, Li Y C, et al. Effect of ignition, initial pressure and temperature on the lower flammability limit of hydrogen/air mixture[J]. International Journal of Hydrogen Energy, 2022, 47(33): 15107-15119.

[31]Zhang Y, Cao W G,Shu C M, et al. Dynamic hazard evaluation of explosion severity for premixed hydrogen–air mixtures in a spherical pressure vessel[J]. Fuel, 2020, 261: 116433.

[32]裴蓓,康亚祥,余明高等.点火延迟时间对CO2-超细水雾的抑爆特性影响[J]. 化工学报, 2022, 73(12): 5672-5684.

[33]王晓彬. 点火延迟时间对甲烷煤尘爆炸特性的影响[J]. 煤矿安全, 2020, 51(3): 23-27.

[34]赵真龙, 陈正, 陈十一. 计算氢气/空气混合物着火延迟时间的相关函数[J]. 科学通报, 2010, 55(11): 1063-1069.

[35]夏萌, 林宇震, 张弛. 正十烷/氢气/空气点火延迟特性数值分析[J]. 中国矿业大学学报, 2014, 43(4): 721-725.

[36]Chang X, Bai C , Zhang B, et al. The effect of ignition delay time on the explosion behavior in non-uniform hydrogen-air mixtures[J]. International Journal of Hydrogen Energy, 2022, 47(16): 9810-9818.

[37]Sun Z Y, Li G X. Turbulence influence on explosion characteristics of stoichiometric and rich hydrogen/air mixtures in a spherical closed vessel[J]. Energy Conversion and Management, 2017, 149: 526-535.

[38]张春燕, 陶刚, 涂善东, 等. 低压氢气-空气混合物爆炸试验研究及数值模拟[J]. 中国安全科学学报, 2018, 28(2): 87.

[39]杨石刚, 方秦, 张亚栋, 等. 非均匀混合可燃气云爆炸的数值计算方法[J].天然气工业, 2014, 34(6): 155-161.

[40]Boeck, L R, Lapointe S, Melguizo G J, et al. Flame propagation across an obstacle: OH-PLIF and 2-D simulations with detailed chemistry[J]. Proceedings of the Combustion Institute, 2017, 36 (2): 2799-2806.

[41]杨国刚, 吴桂涛, 毕明树, 等. 非均匀分布可燃气云爆炸威力分析[J]. 石油学报(石油加工), 2008, (4): 472-477.

[42]杨国刚. 轴对称约束条件下可燃气云爆燃强度研究[D]. 大连: 大连理工大学, 2006.

[43]陈传东. 管道内非均匀预混甲烷/空气爆炸火焰传播特性研究[D].重庆: 重庆大学, 2021.

[44]余明高, 陈传东, 王雪燕, 等. 管道内瓦斯非均匀预混火焰传播特性实验研究[J]. 煤炭学报, 2021, 46(6): 1781-1790.

[45]郗雪辰, 杨鹏飞, 王宽亮. 非均匀氢气/空气混合物中一维爆轰波的振荡特性[J]. 兵工学报, 2023, 44(4): 982-993.

[46]刘振翼, 石世旭, 李明智, 等. 建筑物内非均匀预混天然气泄漏爆炸过程数值模拟[J].安全与环境学报, 2022, 22(5): 2404-2411.

[47]Shen X B, Xu J Y, Jennifer X W. Phenomenological characteristics of hydrogen/air premixed flame propagation in closed rectangular channels[J]. Renewable Energy, 2021, 174: 606-615.

[48]弓亮. 管道内高压氢气泄漏自燃机理实验与数值模拟研究[D]. 合肥: 中国科学技术大学, 2019.

[49]段强领. 高压氢气泄漏自燃机理及其火焰传播特性实验研究[D]. 合肥: 中国科学技术大学, 2016.

[50]向赢, 赵明, 黄鸿, 等. 不同管径的Y形微燃烧器内氢气-空气非预混燃烧的火焰传播特性[J]. 工程热物理学报, 2021, 42(4): 1040-1045.

[51]周宁, 梅苑, 李雪, 等. 管道截面尺寸对氢气火焰传播过程影响的数值模拟[J].安全与环境学报, 2020, 20(06): 2131-2138.

[52]任慧敏, 潘剑锋, 卢青波, 等. 微通道内甲烷/氢气/氧气预混合火焰传播特性[J]. 燃烧科学与技术, 2019, 25(3): 213-219.

[53]郑立刚, 朱小超, 于水军, 等. 浓度和点火位置对氢气-空气预混气爆燃特性影响[J]. 化工学报, 2019, 70(1): 408-416.

[54]李权. 管道内障碍物对氢—空气预混火焰传播动力学影响研究[D]. 合肥: 中国科学技术大学, 2019.

[55]余明高, 阳旭峰, 郑凯, 等. 障碍物对甲烷/氢气爆炸特性的影响[J]. 爆炸与冲击, 2018, 38(1): 19-27.

[56]李雪, 王腾, 陈兵, 等. 置障管道内氢气-空气预混气体的燃爆特性[J]. 油气储运, 2021: 1-8.

[57]Wang C J, Wen J X. Numerical simulation of flame acceleration and deflagration - to -detonation transition in hydrogen -air mixtures with concentration gradients[J]. International Journal of Hydrogen Energy, 2017, 42: 7657-7663.

[58]Saeid M H S, Khadem J, Emami S, et al. Effect of diffusion time on the mechanism of deflagration to detonation transition in an inhomogeneous mixture of hydrogen-air[J]. International Journal of Hydrogen Energy, 2022, 47: 23411-23426.

[59]Azadboni R K, Heidari A, Jennifer X W. Numerical studies of flame acceleration and onset of detonation in homogenous and inhomogeneous mixture[J]. Journal of Loss Prevention in the Process Industries, 2020, 64: 104063.

[60]Lu X Y ,Carolyn R K ,Elaine S O.Transition to detonation in inhomogeneous hydrogen -air mixtures: The importance of gradients in detonation cell size[J]. Proceedings of the Combustion Institute, 2022, 16: 1-9.

[61]韩森.立方舱中浓度梯度氢气爆炸特性研究[D]. 合肥: 合肥工业大学,2019.

[62]Rui S C, Wang C J, Guo S S, et al. Hydrogen-air explosion with concentration gradients in a cubic enclosure[J]. Process Safety and Environmental Protection. 2021, 151: 141-150.

[63]孙智浩. 受限空间内高压氢气泄漏的数值模拟研究[D]. 山东: 山东大学,2019.

[64]辛杰. 受限空间氢气泄漏扩散特性及其浓度时空分布研究[D]. 合肥: 中国科学技术大学, 2023.

[65]时婷婷, 杨福明, 常雪伦, 等. 受限空间内氢气泄漏扩散行为的数值模拟[J]. 太阳能, 2022, (12): 24-31.

[66]黄腾. 大型地下车库内氢气泄漏与扩散研究[D]. 山东: 山东大学, 2022.

[67]屈姣. 甲烷和煤尘爆炸特性实验研究[D].西安: 西安科技大学, 2015.

[68]魏成才.管道中不同气体组分LPG爆燃特性及流场研究[D]. 西安科技大学, 2022.

[69]田莉. 受限空间内氢气/甲烷/空气混合物爆炸特性及抑爆研究[D]. 浙江: 中国计量大学, 2019.

[70]韦双明, 余明高, 裴蓓, 等. 三元混合气体燃料爆炸特性实验研究[J]. 化工学报, 2022, 73(1): 451-460.

[71]Gonzalez M, Borghi R, Saouab A. Interaction of a flame front with its self -generated flow in an enclosure: The “tulip flame” phenomenon[J]. Combust Flame, 1992, 88(2): 343.

[72]Ponizy B, Claverie A, Veyssi`ere B. Tulip flame-the mechanism of flame front inversion[J]. Combust Flame, 2014, 161(12): 3051-3062.

[73]Landau L D. On the theory of slow combustion [J]. Acta Physco Chim USSR, 1944, 19: 77-85.

[74]Christophe C, Geoffrey S. On the “tulip flame” phenomenon [J].Combustion and Flame, 1996, 105, 225-238.

[75]王超. 富燃氢气-空气湍流预混燃烧特性实验研究[D]. 北京: 北京交通大学, 2017.