Numerical analysis of the flame piston-model for acceleration runaway in thin tubes

IF 5.8 2区工程技术 Q2 ENERGY & FUELS

Combustion and Flame Pub Date : 2024-10-10 DOI:10.1016/j.combustflame.2024.113775

Raúl Hernández-Sánchez , Bruno Denet

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引用次数: 0

Abstract

A one-dimensional model is developed and studied to explore the flame acceleration runaway mechanism for deflagration-to-detonation transition in thin tubes. This mechanism relies solely on the thermal feedback between the compression waves ahead of the flame and the temperature-sensitive laminar velocity of the flame. Within this model, the primary driver of the flame acceleration and compressive heating enhancement is the gas flow caused by the increased flame surface area. Results from the numerical integration of the reactive Navier–Stokes equations for perfect gases with a single-step chemical-kinetics model are compared with the solutions obtained when considering the flame as a steady-state discontinuity. The numerical results illustrate the flame acceleration runaway in finite time caused by a double feedback loop established in this model. The evolution of the flame acceleration towards a finite-time singularity eventually leads to the formation of a shock wave within the flame structure, triggering the onset of a detonation.

Novelty and significance statement

This paper presents numerical results obtained using an approach recently proposed to study the effect of flame acceleration on the one-dimensional internal structure of the flame. Unlike previous studies on flame acceleration leading to DDT based on one-dimensional models in which the flame acceleration due to the increase of its surface area is modeled by accelerating chemical kinetics, the present approach consists in the introduction of a backflow of burned gases pushing the flame tip from behind as a piston. The numerical analysis performed in this work allows considering finite reaction rates in this model obtaining results that compare favorably with those obtained when the flame is considered as a discontinuity. The results of this numerical study support previous analytical studies on the flame acceleration runaway mechanism for DDT and illustrate the acceleration process of a flame propagating over a gas flow with a markedly subsonic velocity which leads to the onset of a detonation.

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薄管中加速失控火焰活塞模型的数值分析

建立并研究了一个一维模型，以探索薄管中爆燃到爆燃转变的火焰加速失控机制。该机制完全依赖于火焰前方的压缩波与火焰的温度敏感层流速度之间的热反馈。在这一模型中，火焰加速和压缩加热增强的主要驱动力是火焰表面积增大引起的气体流动。采用单步化学动力学模型对完全气体的反应纳维-斯托克斯方程进行数值积分的结果，与将火焰视为稳态不连续时获得的解进行了比较。数值结果表明，在该模型中建立的双反馈回路导致火焰在有限时间内加速失控。火焰加速度向有限时间奇点的演化最终导致在火焰结构内形成冲击波，引发爆炸。与以往基于一维模型对导致 DDT 的火焰加速进行的研究（其中通过加速化学动力学对由于表面积增加而导致的火焰加速进行建模）不同，本方法包括引入燃烧气体的回流，将火焰尖端作为活塞从后面推动。这项工作中进行的数值分析允许在该模型中考虑有限的反应速率，得到的结果与将火焰视为不连续体时得到的结果相差无几。这项数值研究的结果支持了之前关于滴滴涕火焰加速失控机制的分析研究，并说明了火焰以明显的亚音速在气流中传播并导致爆炸发生的加速过程。

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.