Features of lean premixed flame stabilized on a bluff-body with different temperature magnitude

IF 5.8 2区工程技术 Q2 ENERGY & FUELS

Combustion and Flame Pub Date : 2024-11-09 DOI:10.1016/j.combustflame.2024.113840

Siqi Cai , Wenquan Yang , Lang Li, Jianlong Wan

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Abstract

The bluff-body is widely employed to improve the performance of the lean premixed combustion LPC which has advantages of high efficiency and low pollutant emissions. To further improve the LPC performance stabilized on the bluff-body, the effect of the bluff-body temperature on the lean premixed flame LPF feature near the flammability limit is studied here. The bluff-body temperature is controlled by the electrically heated rod or cooling water, and its values are set as ∼300 K (CB), naturally heat-conducting condition (NHB), 600 K (HB-600), and 900 K (HB-900), respectively. The experimental results show that the flammability limits and LPF behaviors in the case of CB and NHB are nearly the same because of the insignificant difference in the bluff-body temperature magnitude between them. The flammability limit can be significantly extended when the bluff-body temperature is heated to 900 K. Unexpectedly, the stable residual flame appears at the near-limit condition in the case of HB-900. It is the first time to observe the stable residual flame in the case of the fuel of Lewis number Le≈1.0. Then, the flame structures in the case of NHB, HB-600, and HB-900 are revealed numerically. It is found that the fresh reactant arrives at the flame primarily via diffusion rather than convection. The pre-heating effect on the fresh reactants and heat-loss effect to the bluff-body are also evaluated quantitatively. In the case of NHB, the flame can be classified to the adiabatic zone and mixed zone. By contrast, in the case of HB-600 and HB-900, the flame can be classified to the adiabatic zone, excess reaction zone, and weak reaction zone. This study expands our understanding on improving the LPC performance via controlling the bluff-body temperature.

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在不同温度幅度的崖体上稳定的贫油预混火焰的特征

崖体被广泛用于改善贫油预混燃烧 LPC 的性能，它具有高效率和低污染排放的优点。为了进一步提高稳定在崖体上的 LPC 性能，本文研究了崖体温度对可燃极限附近贫油预混火焰 LPF 特性的影响。崖体温度由电热棒或冷却水控制，其值分别设定为 300 K（CB）、自然导热条件（NHB）、600 K（HB-600）和 900 K（HB-900）。实验结果表明，CB 和 NHB 的可燃极限和 LPF 行为几乎相同，这是因为它们的崖体温度大小差异不大。令人意外的是，HB-900 在接近极限的条件下出现了稳定的残焰。这是首次在路易斯数 Le≈1.0 的燃料中观察到稳定残焰。然后，用数值方法揭示了 NHB、HB-600 和 HB-900 的火焰结构。研究发现，新鲜反应物主要通过扩散而非对流到达火焰。此外，还定量评估了新鲜反应物的预热效果和崖体的热损失效果。对于 NHB，火焰可分为绝热区和混合区。相比之下，HB-600 和 HB-900 的火焰可分为绝热区、过量反应区和弱反应区。这项研究拓展了我们对通过控制崖体温度改善 LPC 性能的理解。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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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.