On electrode placement in plasma-assisted ignition of a scramjet flame-holder

IF 6.2 2区工程技术 Q2 ENERGY & FUELS

Combustion and Flame Pub Date : 2025-08-28 DOI:10.1016/j.combustflame.2025.114408

Rajath Shetty , Cesar Cardenas , Luca Massa

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引用次数: 0

Abstract

A multi-scale model for plasma-assisted combustion is developed to investigate how the location of the electrodes in the cavity affects the ignition of supersonic flows in nanosecond repetitive pulse discharges. A new approach to plasma-fluid coupling is investigated that relies on solving the detailed plasma and photon transport equations on a near-electrode block partition of the overall mesh during the pulse and synchronizing the thermochemical balances with the reactive-fluid mesh by interpolation. The approach reproduces experimental observations of assisted ignition: the formation of trailing-edge flames in high-enthalpy conditions, the formation of localized ignition kernels near the cathode for medium-enthalpy conditions, and the presence of a distributed region of elevated OH mass fraction for conditions leading to no ignition. The approach matches the experimental measurement of plasma-energy coupling. The analysis emphasizes the significance of fluid strain rate in plasma-fluid coupling. The location of the electrode is found to affect ignition by supporting a larger radical turnover by plasma when the electrodes are placed in regions of lower strain, leading to a thicker reaction region.

Novelty, Significance, and Contributions: A novel computational approach to plasma-gas coupling is developed and validated. This approach was applied to investigate the influence of strain rate on the focusing of pre-ionization electrons in the low-shear region of cavity stabilizers. The authors identify a correlation between strain rate and radical turnover number. This study led to the determination of the contribution of electrode placement to the efficacy of plasma actuation in supersonic flame-holders. The importance of the cathode location to supersonic ignition is investigated for the first time in detail. This research presents a significant advancement of previously published works: it models photoionization from first principles and includes the gas-plasma interactions in a three-dimensional turbulent flow.

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超燃冲压发动机火焰座等离子辅助点火的电极放置研究

建立了等离子体辅助燃烧的多尺度模型，研究了在纳秒重复脉冲放电中，电极在腔内的位置对超声速流动点火的影响。研究了一种等离子体-流体耦合的新方法，该方法依赖于在脉冲期间在整体网格的近电极块分区上求解详细的等离子体和光子输运方程，并通过插值将热化学平衡与反应流体网格同步。该方法再现了辅助点火的实验观察：在高焓条件下形成尾缘火焰，在中焓条件下在阴极附近形成局部点火核，以及在导致不点火的条件下存在高OH质量分数的分布区域。该方法与等离子体能量耦合的实验测量结果相匹配。分析强调了流体应变率在等离子体-流体耦合中的重要意义。当电极放置在较低应变区域时，电极的位置通过支持等离子体较大的自由基周转来影响点火，从而导致较厚的反应区域。新颖性、重要性和贡献：一种新的等离子体-气体耦合计算方法被开发和验证。应用该方法研究了应变速率对腔稳定剂低剪切区预电离电子聚焦的影响。作者确定了应变速率和自由基周转率之间的相关性。该研究确定了电极放置对超音速火焰支架中等离子体驱动效果的贡献。本文首次详细探讨了阴极位置对超声速点火的重要性。这项研究在先前发表的作品的基础上取得了重大进展：它从第一性原理模拟了光电离，并包括了三维湍流中的气体-等离子体相互作用。

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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.