Experimental Investigation of the Transition Mechanism From Stable Flame to Flashback in a Generic Premixed Combustion System With High-Speed Micro-Particle Image Velocimetry and Micro-PLIF Combined With Chemiluminescence Imaging
Experimental Investigation of the Transition Mechanism From Stable Flame to Flashback in a Generic Premixed Combustion System With High-Speed Micro-Particle Image Velocimetry and Micro-PLIF Combined With Chemiluminescence Imaging
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DOI：
10.1115/1.4031227
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发表时间：
2016-02-01
影响因子：
1.5
通讯作者：
Sattelmayer, Thomas
中科院分区：
文献类型：
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作者：
Baumgartner, Georg;Boeck, Lorenz R.;Sattelmayer, Thomas
在不久的将来，实现低二氧化碳和氮氧化物等污染物排放的可持续发电是一项非常具有挑战性的任务。在燃气轮机中预混燃烧富氢燃料是一种很有前途的方法，可以应对日益严格的排放水平法规。然而，这种方法有火焰从期望的火焰位置闪回预混段的风险，导致机器部件的灾难性故障，这些部件不是为这种高温设计的。当前研究的目的是可视化和描述一般h -2-空气燃烧系统中从稳定火焰到闪回的转变，并开发一个基于物理的模型来描述这种转变。为了达到捕获相关效应所需的高时空分辨率，采用了高速粒子图像测速（PIV）和高速平面激光诱导荧光（PLIF）技术。为了详细表征火焰与流动的相互作用，这两种测量技术都应用于非常小的视场，使用（UV）远程显微镜。PLIF和PIV的重复频率分别为20 kHz和3 kHz。在PLIF和PIV测量期间，从垂直于PLIF/PIV相机的角度捕获火焰的OH*化学发光，以进一步表征火焰。微观测量结果表明，在稳定模式下，无约束火焰对进入燃烧器流动的影响可以忽略不计。然而，在接近闪回条件时，由于预混管道内火焰的存在，燃烧器流动的速度分布明显扭曲。火焰直接上游的流动被阻滞，并在火焰尖端周围偏转。在实验的基础上，提出了一种新的闪回模型，该模型认为闪回的主要驱动因素是燃烧器边缘的传热和火焰速度，而火焰反压是随后上游火焰传播的控制因素。
Sustainable power generation resulting in low pollutant emissions, such as CO2 and NOx, poses a very challenging task in the near future. Premixed combustion of hydrogen-rich fuels in gas turbines is a promising approach to cope with ever more stringent regulations on emission levels. This method, however, involves the risk of flame flashback from the desired flame position into the premixing section, leading to catastrophic failure of the machine components that are not designed for such high temperatures. The objective of the current study was to visualize and describe the transition from stable flame to flashback in a generic H-2-air combustion system and develop a physics-based model for the description of the transition. In order to achieve the high temporal and spatial resolution required for capturing the involved effects, high-speed particle image velocimetry (PIV) and high-speed planar laser-induced fluorescence (PLIF) were employed. In order to characterize the interaction of the flame with the flow in detail, both measurement techniques were applied to very small fields-of-view using (UV) long-distance microscopes. The repetition rates were 20 kHz for PLIF and 3 kHz for PIV, respectively. During both the PLIF and the PIV measurements, the flame's OH*-chemiluminescence was captured from a perspective perpendicular to that of the PLIF/PIV camera for further flame characterization. The microscopic measurements revealed that there is a negligible influence of the unconfined flame on the incoming burner flow in stable mode. Upon approaching the flashback conditions, however, the velocity profile of the burner flow is distinctly distorted by the presence of the flame inside the premixing duct. The flow directly upstream of the flame is retarded and deflected around the leading flame tip. Based on the effects observed in the experiments, a new flashback model is proposed, which identifies the heat transfer to the burner rim and the flame speed as the main drivers for the onset of flashback, whereas the flame backpressure is the governing factor for the subsequent upstream flame propagation.