Investigation of combustion instability caused by different fuels combustion induced backpressure in a scramjet engine

IF 5.8 2区工程技术 Q2 ENERGY & FUELS

Combustion and Flame Pub Date : 2025-03-28 DOI:10.1016/j.combustflame.2025.114142

Guangming Du , Erda Chen , Changchun Yan , Yitong Zhao , Yueqian Zhou , Ye Tian , Jialing Le

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引用次数: 0

Abstract

The study examines the influence of kerosene and ethylene fuels on combustion instability characteristics at various equivalence ratios, with the objective of investigating supersonic combustion instability induced by combustion-induced backpressure. It was revealed that flow separation, triggered by this backpressure, plays a crucial role in combustion instability. The propagation of flow separation upstream can be classified into three typical flow states, with the timing between these states dependent on the fuel type and equivalence ratio. Hysteresis effects were noted during the flow separation propagation in both upstream and downstream directions. Different fuels and equivalence ratios have a direct impact on the magnitude of combustion-induced backpressure. Lower backpressure is linked to decreased combustion intensity and a flame front position closer to the upstream region, resulting in distinct combustion instability characteristics. Spectral analysis indicated that low-frequency oscillations (100–200 Hz) are associated with flame flashback and blowoff, while mid-to-low frequency oscillations (300–1000 Hz) originate from oscillations between the upstream and downstream regions of the combustor and the cavity shear layer. High-frequency oscillations (1000–3000 Hz) are connected to acoustic self-excited oscillations within the cavity. Correlation analysis was performed between the flame luminosity intensity in different combustor regions and the total luminosity intensity to clarify the oscillation characteristics of the cavity recirculation zone and the cavity shear layer. A method was developed using a weighted Damköhler number to evaluate combustion stability, taking into account the contributions of the cavity recirculation zone stabilized mode and the cavity shear layer stabilized mode. The results of this method regarding flame stability are in good agreement with the experimental observations.

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超燃冲压发动机不同燃料燃烧引起的背压引起的燃烧不稳定性研究

本研究考察了煤油和乙烯燃料在不同当量比下对燃烧不稳定特性的影响，目的是研究燃烧诱导背压引起的超声速燃烧不稳定。结果表明，由反压引起的流动分离对燃烧不稳定性起着至关重要的作用。流动分离在上游的传播可以分为三种典型的流动状态，这些状态之间的时间取决于燃料类型和当量比。在上游和下游两个方向的流动分离传播过程中都存在滞后效应。不同的燃料和当量比对燃烧背压的大小有直接的影响。较低的背压与燃烧强度降低和火焰锋面位置更靠近上游区域有关，从而导致明显的燃烧不稳定特征。频谱分析表明，低频振荡（100-200 Hz）与火焰闪回和吹散有关，而中低频振荡（300-1000 Hz）来自燃烧室上下游区域与腔体剪切层之间的振荡。高频振荡（1000-3000赫兹）连接到腔内的声学自激振荡。对不同燃烧区域的火焰亮度强度与总亮度强度进行相关性分析，明确空腔再循环区和空腔剪切层的振荡特性。考虑空腔再循环区稳定模式和空腔剪切层稳定模式的贡献，建立了一种利用Damköhler数加权评价燃烧稳定性的方法。该方法的火焰稳定性计算结果与实验结果吻合较好。

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.