Scaling and prediction of transfer functions in lean premixed H2/CH4-flames

Æsøy, Eirik; Aguilar, José G.; Wiseman, Samuel; Bothien, Mirko R.; Worth, Nicholas A.; Dawson, James

doi:10.1016/j.combustflame.2020.01.045

Cited by 66 publications

(9 citation statements)

References 36 publications

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“…The asymmetry has a number of potential sources: First, the bluff body is centred with three grub screws which is known to introduce azimuthal asymmetry around the flame (Æsøy et al. 2020 ); second, the flame is confined in annular geometry, with a quartz outer annulus, a metal inner annulus, and neighbouring flames either side; third, the bluff body is expected to be imperfectly centered, and small manufacturing asymmetries may also be present; and forth, the flow from the cylindrical plenum upstream may not be perfectly uniform, due to the relatively short inlet tube length, . From above, the OH distribution has a slightly triangular shape, which is perhaps a result of the three grub screws.…”

Section: Resultsmentioning

confidence: 99%

Large volume scanning laser induced fluorescence measurement of a bluff-body stabilised flame in an annular combustor

et al. 2022

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This study outlines a variant of three-dimensional OH planar laser-induced fluorescence and its application in characterising a single bluff body stabilised flame inside a 12 burner annular combustor. In this variant of the method a relatively large volume was scanned slowly in order to calculate the full three-dimensional Flame Surface Density (FSD) distribution. The method used a combination of two scanning directions to overcome bias errors associated with laser sheet positions close to the flame edges. The source of this bias error was confirmed numerically through a complimentary synthetic PLIF study, which was also used to refine the experimental setup. The bias error resulted in a reduction of FSD magnitude, although the method was still capable of capturing the flame structure. This was demonstrated by comparing the reconstructions from the two independent scan directions. Combining the data from both directions overcame the bias, and allowed flame asymmetry due to the confinement to be assessed. The FSD was used to determine the heat release rate of the flame with varying local azimuthal angle for different downstream regions. This highlighted the highly asymmetric structure, produced by the asymmetric confinement. Graphical abstract

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Section: Resultsmentioning

confidence: 99%

Large volume scanning laser induced fluorescence measurement of a bluff-body stabilised flame in an annular combustor

et al. 2022

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“…This current is amplified to a 0–5 V voltage using an impedance amplifier (Hamamatsu C7319). PMT values are used to characterize the flame heat release rate. − The pressure and heat release signals are collected simultaneously based on the NI data acquisition system for velocity fluctuation and heat release rate fluctuation. These data are passed to LabVIEW software in the computer through the output signal cable for high-speed operation and storage.…”

Section: Experimental Apparatus and Conditionsmentioning

confidence: 99%

Analysis of Combustion Instability of Methane–Air Premixed Swirling Flame Based on OH-PLIF Measurements

et al. 2023

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A method for determining combustion instability using flame structure parameters is presented. A speaker is used to provide controllable external excitation for the combustion system. The experimental object is a methane−air swirl premixed flame. The flame structure parameters such as height, width, and flame surface density extracted from the hydroxyl planar laser-induced fluorescence image were used to analyze combustion instability at different equivalence ratios (0.8−1.2) and inlet flow rates. It is confirmed that the inflection point of the flame structure parameters corresponds to the evolution of combustion instability verified by the flame transfer function. The results show that with the increase of inlet velocity v, the flame aspect ratio h/b, average OH* concentration, and surface density Σ gradually decrease. The thickness δ of the flame brush shows an increasing trend under the same conditions. With the increase of equivalence ratio Φ, the average OH* concentration and flame surface density Σ increase continuously. The changing trend of flame brush thickness decreases first and then increases to a peak. Finally, it continues to decline after reaching the peak. The flame responds strongly to the sound field when the equivalence ratio is 0.9 and 1.0. In the range of 80−240 Hz, the flame response near 110 and 190 Hz is stronger at each equivalence ratio (0.8−1.0). When the equivalent ratio is 0.9 and 1.0, the amplitude fluctuations of the flame transfer function are much larger than those under other conditions. Meanwhile, the specific performances of the flame structure parameters are that the flame height, average OH* concentration, and flame surface density decrease, and the flame brush thickness increases. These results can be used as a basis for judging combustion instability. This method proves that the parameter information monitored during the flame combustion process can be used to judge the changes in combustion conditions and can adjust the corresponding conditions more accurately and quickly.

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“…Despite these positive aspects, hydrogen shows some other challenging technical issues that must be addressed, such as potential flashback and autoignition due to its significantly higher flame speed and shorter autoignition time. Furthermore, an excessive lean combustion can lead to dangerous thermoacoustic instabilities [12][13][14][15][16][17]. This will require some modifications of current design features.…”

Section: Hydrogenmentioning

confidence: 99%

Recent Combustion Strategies in Gas Turbines for Propulsion and Power Generation toward a Zero-Emissions Future: Fuels, Burners, and Combustion Techniques

et al. 2021

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The effects of climate change and global warming are arising a new awareness on the impact of our daily life. Power generation for transportation and mobility as well as in industry is the main responsible for the greenhouse gas emissions. Indeed, currently, 80% of the energy is still produced by combustion of fossil fuels; thus, great efforts need to be spent to make combustion greener and safer than in the past. For this reason, a review of the most recent gas turbines combustion strategy with a focus on fuels, combustion techniques, and burners is presented here. A new generation of fuels for gas turbines are currently under investigation by the academic community, with a specific concern about production and storage. Among them, biofuels represent a trustworthy and valuable solution in the next decades during the transition to zero carbon fuels (e.g., hydrogen and ammonia). Promising combustion techniques explored in the past, and then abandoned due to their technological complexity, are now receiving renewed attention (e.g., MILD, PVC), thanks to their effectiveness in improving the efficiency and reducing emissions of standard gas turbine cycles. Finally, many advances are illustrated in terms of new burners, developed for both aviation and power generation. This overview points out promising solutions for the next generation combustion and opens the way to a fast transition toward zero emissions power generation.

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Scaling and prediction of transfer functions in lean premixed H2/CH4-flames

Cited by 66 publications

References 36 publications

Large volume scanning laser induced fluorescence measurement of a bluff-body stabilised flame in an annular combustor

Large volume scanning laser induced fluorescence measurement of a bluff-body stabilised flame in an annular combustor

Analysis of Combustion Instability of Methane–Air Premixed Swirling Flame Based on OH-PLIF Measurements

Recent Combustion Strategies in Gas Turbines for Propulsion and Power Generation toward a Zero-Emissions Future: Fuels, Burners, and Combustion Techniques

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