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arXiv 2302.07006physics.flu-dyn
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Taylor-Green涡与氢扩散火焰相互作用的直接数值模拟:Reynolds数及非单位Lewis数效应

Direct numerical simulations of the Taylor-Green Vortex interacting with a hydrogen diffusion flame: Reynolds number and non-unity Lewis number effects

Yifan Xu, Zhi X. Chen

AI总结:

本文通过多组DNS研究嵌入TGV的氢扩散火焰,揭示Reynolds数升高引起的涡管演化、火焰热释放与湍流的双向作用,以及非单位Lewis数效应受强湍流抑制的规律。

摘要:

理解氢火焰与湍流涡之间的相互作用,对于开发下一代碳中和燃烧系统十分重要。在本研究中,我们开展了若干直接数值模拟(DNS)工况,以研究嵌入Taylor-Green涡(TGV)中的氢扩散火焰的动力学特性。在最高达3200的一系列初始Reynolds数下,并采用不同的质量扩散模型,考察了火焰与涡的演化。结果表明,在低Reynolds数工况中,涡迅速耗散;而在高Reynolds数、出现明显湍流转捩的工况中,可观察到涡管持续的拉伸、分裂与扭曲。关于火焰与涡之间的相互作用,研究表明火焰产生的热释放对TGV的湍流强度及其发展具有抑制作用。同时,强烈湍流提供了丰富的动能,加速了扩散火焰的混合,并促成更高的应变率和更大的火焰曲率。考虑非单位Lewis数的影响后发现,在采用混合物平均模型的工况中,火焰强度更为剧烈;然而,在强烈湍流的作用下,这种效应受到相对抑制。

英文摘要:

Understanding the interactions between hydrogen flame and turbulent vortices is important for developing the next-generation carbon neutral combustion systems. In the present work, we perform several direct numerical simulation (DNS) cases to study the dynamics of a hydrogen diffusion flame embedded in the Taylor-Green Vortex (TGV). The evolution of flame and vortex is investigated for a range of initial Reynolds numbers up to 3200 with different mass diffusion models. We show that the vortices dissipate rapidly in cases at low Reynolds numbers, while the consistent stretching, splitting and twisting of vortex tubes are observed in cases with evident turbulence transition at high Reynolds numbers. Regarding the interactions between the flame and vortex, it is demonstrated that the heat release generated by the flame has suppression effects on the turbulence intensity and its development of the TGV. Meanwhile, the intense turbulence provides abundant kinetic energy, accelerating the mixing of the diffusion flame with a contribution to higher strain rate and larger curvatures of the flame. Considering the effects of non-unity Lewis number, it is revealed that the flame strength is more intense in the cases with mixture averaged model. However, this effect is relatively suppressed under the impacts of the intense turbulence.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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