Chemiluminescence as diagnostic tool in the development of gas turbines

Guethe, Felix; Guyot, Daniel; Singla, Ghislain; Noiray, Nicolas; Schuermans, Bruno

doi:10.1007/s00340-012-4984-y

Cited by 39 publications

(16 citation statements)

References 31 publications

(46 reference statements)

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“…These applications need fast, robust, and nonintrusive sensors [15]. Chemiluminescence of flames may provide a wellsuited, low-cost inherent monitor of the combustion process [1,8,26,28,30,39], since the emission of excited species from flames is intricately coupled to the flame chemistry. Chemiluminescence intensities and intensity ratios involving mostly OH * , CH * and C * 2 emissions have been analyzed and correlated to combustion properties such as stoichiometry and heat release, and this potential suggests their application in control.…”

Section: Introductionmentioning

confidence: 99%

Measurement and simulation of rotationally-resolved chemiluminescence spectra in flames

et al. 2012

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In recent years, there has been renewed interest in chemiluminescence, since it has been shown that these emissions can be used to determine flame parameters such as stoichiometry and heat release under some conditions. Even though the origin of these emissions has been known for a long time, little attention has been paid to the detailed analysis of the spectral structure.In this contribution, we present rotationally-resolved spectra of all important chemiluminescent emissions OH A-X, CH B-X, CH A-X, and C 2 d-a in CH 4 /air flames. A numerical model based on the LASKINν 2 code has been developed that allows, for the first time, to accurately predict the shape of the measured spectra for all of these transitions. Reabsorption of chemiluminescence within the emitting flame is shown to be a major factor, affecting both intensity and structure of OH * spectra. Even in lab-scale flames, it might change the intensity of individual lines by a factor of 5. The shape of chemiluminescence spectra depends on several processes including initial state distribution and rotational and vibrational energy transfer (which, in turn, depend on the collisional environment and the temperature). It is shown that chemical reactions form OH * in highly excited states and that the number of collisions is not sufficient to equilibrate the initial distribution. Therefore, high apparent temperatures are necessary to describe the shape of the measured spectra. In contrast, CH * is formed with less excess energy and the spectral shape is very close to thermal. The rotational structure of C * 2 is close to thermal equilibrium as well. Vibrational temperatures are, however, signif-A. Brockhinke ( ) · J. Krüger · M. Heusing · M. Letzgus icantly higher than the flame temperature. Implications and perspectives for flame measurements are discussed.

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Section: Introductionmentioning

confidence: 99%

Measurement and simulation of rotationally-resolved chemiluminescence spectra in flames

et al. 2012

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“…The chemiluminescence emission has been assumed to be proportional to the total heat-release rate [9,22,23] . At each test point, the pressure and PMT data are sampled at a frequency of 8192 Hz for 4 s on a data acquisition system (National Instruments, BNC-2111), resulting in a spectral resolution of 0.25 Hz and a temporal resolution of 0.122 ms. All of the experiments are performed at ambient temperature ( T a = 293 K) and atmospheric pressure.…”

Section: Methodsmentioning

confidence: 99%

Extracting flame describing functions in the presence of self-excited thermoacoustic oscillations

Balusamy

Han

et al. 2017

Proceedings of the Combustion Institute

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One of the key elements in the prediction of thermoacoustic oscillations is the determination of the acoustic response of flames as an element in an acoustic network, in the form of a flame describing function (FDF). In order to obtain a response, flames often have to be confined into a system with its own acoustic response. Separating the pure flame response and that of the system can be complicated by the non-linear effects that the flame can have on the overall system response. In this paper, we investigate whether it is possible to obtain a flame response via the usual methods of dynamic chemiluminescence and pressure measurements, starting from an unforced system with incipient self-excitations at a given frequency f s , in the form of a stabilized flame at atmospheric pressure with a 700 mm tube as a combustor. The flame is forced at discrete frequencies from 20 to 400 Hz, away from the self-excitation, and the response of the flame is measured using OH * chemiluminescence. This response was compared to a flame response measured in a short tube with no other excitations.The results show that both the gain and phase can be entirely dominated by the behavior of the self-excitation, so that in general it is not possible to extract reliable gain and phase information as if the forced and selfexcited modes acted independently and linearly. Although the gain in this particular case was not significantly affected, the phase information of the original flame became dominated by the triggered self-excitation.Boundary conditions and systems used for flame acoustic forcing therefore need to be carefully controlled whenever there is a possibility of self-excitation.

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“…Recording the natural emission from the flame is the simplest diagnostic yielding time-resolved estimates of heat release rate fluctuations [4,5]. Effects of the turbulence intensity, strain rate, flame front curvature, mixture composition, temperature and pressure need however to be included to obtain quantitative heat release rate data [6][7][8][9][10][11][12][13][14]. These studies stress out the need of alternative techniques to measure heat release rate disturbances.…”

Section: Introductionmentioning

confidence: 98%

Analysis of chemiluminescence, density and heat release rate fluctuations in acoustically perturbed laminar premixed flames

Li¹,

Durox²,

Richecoeur³

et al. 2015

Combustion and Flame

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Chemiluminescence as diagnostic tool in the development of gas turbines

Cited by 39 publications

References 31 publications

Measurement and simulation of rotationally-resolved chemiluminescence spectra in flames

Measurement and simulation of rotationally-resolved chemiluminescence spectra in flames

Extracting flame describing functions in the presence of self-excited thermoacoustic oscillations

Analysis of chemiluminescence, density and heat release rate fluctuations in acoustically perturbed laminar premixed flames

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