Propagation of ultra-lean hydrogen/air flames in a Hele-Shaw cell

IF 6.2 2区工程技术 Q2 ENERGY & FUELS

Combustion and Flame Pub Date : 2025-08-31 DOI:10.1016/j.combustflame.2025.114444

Linlin Yang , Yan Wang , Tianhan Zhang , Xiaolong Gou , Wenjun Kong , Zheng Chen

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引用次数: 0

Abstract

Ultra-lean hydrogen flame is closely related to hydrogen safety. Recently, different types of hydrogen flame have been observed in experiments under ultra-lean conditions. However, the evolution and propagation of ultra-lean hydrogen flames are still not well understood. In this study, 3D simulations considering detailed chemistry and transport models are conducted for ultra-lean premixed hydrogen/air flames propagating in an open Hele-Shaw cell with isothermal walls. It is found that ultra-lean hydrogen flames are very sensitive to equivalence ratio, ϕ. As ϕ decreases from 0.225 to 0.21, different cellular flame regimes, including two-headed branching, two-headed finger and one-headed finger (ball-like flame) are sequentially observed. The cell size shows a decreasing tendency. Isolated ball-like flames and two-headed finger are stable in the ultra-lean mixture. During the flame cell propagation, both heat loss and heat release exhibit oscillatory characteristics since they are correlated with each other. The oscillation frequency is found to increase with ϕ. In order to balance the conductive heat loss to walls, two-headed flames split while isolated ball-like flames shrink, resulting in periodic changes in flame surface area and heat release rate. Moreover, ultra-lean flames are found to be characterized by high local equivalence ratio caused by strong differential diffusion of hydrogen over other species, highlighting the effect of diffusional-thermal instability (DTI) on sustaining the ultra-lean flame. Furthermore, stable ball-like flames and two-headed finger can exist simultaneously. Interestingly, flame instabilities play a stabilizing role in the ultra-lean flames. Darrieus-Landau instability (DLI) contributes to the stabilization of two-headed finger flames with strong mutual interaction between adjacent cells, whereas ball-like flames dominated by DTI tend to move away from each other to gain deficient fuel and drift in a zigzag manner. The present 3D simulations help to understand flame cell propagation and stabilization in ultra-lean hydrogen/air mixture within an open Hele-Shaw cell.

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超稀薄氢气/空气火焰在Hele-Shaw电池中的传播

超贫氢火焰与氢安全密切相关。近年来，在超贫条件下的实验中观察到不同类型的氢火焰。然而，超贫氢火焰的演化和传播仍未得到很好的理解。在这项研究中，考虑了详细的化学和传输模型，进行了超贫预混氢/空气火焰在具有等温壁的开放式Hele-Shaw池中传播的三维模拟。发现超贫氢火焰对等效比φ非常敏感。当φ从0.225减小到0.21时，依次观察到不同的细胞火焰制度，包括双头分支，双头手指和单头手指（球形火焰）。细胞大小呈减小趋势。孤立的球形火焰和双头指在超稀混合物中是稳定的。在火焰细胞的传播过程中，热损失和热释放都表现出振荡特性，因为它们是相互关联的。振荡频率随着φ的增大而增大。为了平衡传导到壁面的热损失，双头火焰分裂，而孤立的球形火焰收缩，导致火焰表面积和放热率的周期性变化。此外，发现超稀薄火焰的特点是由氢对其他物质的强微分扩散引起的高局部等效比，突出了扩散热不稳定性（DTI）对维持超稀薄火焰的作用。此外，稳定的球状火焰和双头手指可以同时存在。有趣的是，火焰不稳定性在超稀薄火焰中起着稳定作用。DLI不稳定性（drieus - landau instability， DLI）有助于双头指状火焰的稳定，相邻细胞之间的相互作用很强，而DTI主导的球形火焰往往会相互远离，从而获得不足的燃料，并以之字形的方式漂移。目前的三维模拟有助于理解开放式Hele-Shaw槽内超稀薄氢/空气混合物中火焰细胞的传播和稳定。

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来源期刊

Combustion and Flame 工程技术-工程：化工

CiteScore

9.50

自引率

20.50%

发文量

631

审稿时长

3.8 months

期刊介绍： The mission of the journal is to publish high quality work from experimental, theoretical, and computational investigations on the fundamentals of combustion phenomena and closely allied matters. While submissions in all pertinent areas are welcomed, past and recent focus of the journal has been on: Development and validation of reaction kinetics, reduction of reaction mechanisms and modeling of combustion systems, including: Conventional, alternative and surrogate fuels; Pollutants; Particulate and aerosol formation and abatement; Heterogeneous processes. Experimental, theoretical, and computational studies of laminar and turbulent combustion phenomena, including: Premixed and non-premixed flames; Ignition and extinction phenomena; Flame propagation; Flame structure; Instabilities and swirl; Flame spread; Multi-phase reactants. Advances in diagnostic and computational methods in combustion, including: Measurement and simulation of scalar and vector properties; Novel techniques; State-of-the art applications. Fundamental investigations of combustion technologies and systems, including: Internal combustion engines; Gas turbines; Small- and large-scale stationary combustion and power generation; Catalytic combustion; Combustion synthesis; Combustion under extreme conditions; New concepts.