Simultaneous measurement of localized heat release with OH/CH2O-LIF imaging and spatially integrated OH∗ chemiluminescence in turbulent swirl flames

Röder, Markus; Dreier, Thomas; Schulz, Christof

doi:10.1007/s00340-012-4990-0

Cited by 32 publications

(14 citation statements)

References 23 publications

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“…[OH][CH 2 O], where [A] indicates the molar concentration of species A, has been used in a number of studies, for example [9][10][11][12][13][14][15][16][17], as the de facto standard to infer heat release rate related information in laminar and turbulent premixed flames irrespective of the fuel mixture composition and stoichiometry.…”

Section: Introductionmentioning

confidence: 99%

Heat release rate markers for premixed combustion

Nikolaou

Swaminathan

2014

Combustion and Flame

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a b s t r a c tThe validity of the commonly used flame marker for heat release rate (HRR) visualization, namely the rate of the reaction OH + CH 2 O , HCO + H 2 O is re-examined. This is done both for methane-air and multicomponent fuel-air mixtures for lean and stoichiometric conditions. Two different methods are used to identify HRR correlations, and it is found that HRR correlations vary strongly with stoichiometry. For the methane mixture there exist alternative HRR markers, while for the multi-component fuel flame the above correlation is found to be inadequate. Alternative markers for the HRR visualization are thus proposed and their performance under turbulent conditions is evaluated using DNS data.

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Section: Introductionmentioning

confidence: 99%

Heat release rate markers for premixed combustion

Nikolaou

Swaminathan

2014

Combustion and Flame

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“…These studies reveal peak temperatures which occur away from the exit plane at x=25mm (x/D=0.5) but in the vicinity of centrally located flow reversals measured on this burner. Testing done on premixed (CH 4 -air) Tecflam flames also reveals flame fronts which are continuous, but wrinkled [51]. The likelihood of flashback accompanied with precession, when using premixed fuels, has also been shown to occur at a critical swirl number which increases with Reynolds number (bulk flow velocity) [50].…”

Section: Unconfined Burnersmentioning

confidence: 96%

“…When the annular swirling stream delivers fuel, a central bluff-body has featured [48], but there has also been one set of results reported whereby a quarl has been added to the burner mouth combined with a central orifice within the bluffbody [49]. In some reported outcomes, this bluff-body is also said to be water cooled, as shown in Figure 1c, so as to promote well-defined/stable boundary conditions when studying flame flashback/back-propagation [50] and heat release [51]. Additionally, work done on this burner has included both non-premixed (methane) [46,47] and premixed (methane-air) fuels [48].…”

Section: Tecflam Swirl Burnermentioning

confidence: 99%

Review of laboratory swirl burners and experiments for model validation

Al-Abdeli

Masri

2015

Experimental Thermal and Fluid Science

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“…The reaction zone thickness is defined to be the width of the CH 2 O-OH overlap layer at 50% of its maximum value (FWHM). Previous studies [27][28][29][30][31][32][33][34][35][36][37][38][39][40] have also used the overlap of OH and CH 2 O or HCO to define the reaction layer. This is because the primary pathway for HCO production (and subsequently heat release) involves reactions with CH 2 O and OH.…”

Section: A Burner Design and Diagnosticsmentioning

confidence: 99%

Measurements to Determine the Regimes of Turbulent Premixed Flames

Skiba

Wabel

Temme

et al. 2015

51st AIAA/SAE/ASEE Joint Propulsion Conference

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Structural features of highly turbulent piloted flames were acquired from simultaneous PLIF images of formaldehyde (CH 2 O) and OH. The lean (equivalence ratio = 0.75) methane-air flames were studied under eight different flow conditions and at two different interrogation regions. The non-reacting conditions for these flames consist of turbulent Reynolds numbers (Re T ), turbulence intensities (u'/S L ), and integral length scales that range from 520 to 80,000, 5 to 184, and 6 mm to 29 mm, respectively. Preheat and reaction zone thicknesses were measured for flames subjected to these range of values. The preheat zone thickness was deduced from the CH 2 O PLIF images and the reaction zone thicknesses were obtained from the profiles produced by the pixel-by-pixel product of the OH and CH 2 O PLIF images. The reaction or preheat zones associated with a particular condition were classified as being "thickened" if the mean thickness for that condition exceeded two but not four times the laminar value. If the average thickness was greater than four times the laminar value that preheat or reaction zone was deemed "primarily distributed." Eight of the eleven cases possessed "primarily distributed" preheat zones, while the other three were "thickened." A reaction zone was further characterized as being "moderately distributed" if more than 20% but less than 40% of it was identified as being "locally distributed." A particular portion of a reaction zone is found to be "locally distributed" if that portion is both four times thicker than the laminar value and its length to thickness ratio is less than four. All of the reaction zones near the burner's exit were "thickened" and, except in one case, were also deemed "moderately distributed." Additionally, all of the reaction layers in the downstream interrogation region were "primarily distributed." Yet, regardless of being categorized as "moderately" or "primarily distributed," each case's reaction zones exhibited regions of both relatively thin and distributed reactions. In fact the appearance of the observed reaction zones can best be described as resembling "chicken noodle soup." That is, in any given instantaneous image relatively thin, "noodle-like" reaction layers are generally accompanied by thicker "chunky-chicken-like" reaction regions. Furthermore, the observed reaction zone structures in a particular case typically fail to correspond to those predicted by the turbulent premixed combustion regime diagram. This suggests that the regime diagram requires alterations if it is to properly forecast the appearance of a flame based on a simple set of operating conditions. The data set presented here is currently too limited to enable a thorough re-mapping of the regime diagram. However, based on their structural features, the cases considered here were classified into appropriate regimes of combustion.

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Simultaneous measurement of localized heat release with OH/CH2O-LIF imaging and spatially integrated OH∗ chemiluminescence in turbulent swirl flames

Cited by 32 publications

References 23 publications

Heat release rate markers for premixed combustion

Heat release rate markers for premixed combustion

Review of laboratory swirl burners and experiments for model validation

Measurements to Determine the Regimes of Turbulent Premixed Flames

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