Statistics of local and global flame speed and structure for highly turbulent H<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si7.svg"><mml:msub><mml:mrow/><mml:mn>2</mml:mn></mml:msub></mml:math>/air premixed flames

Song, Wonsik; Pérez, Francisco E. Hernández; Tingas, Efstathios-Al.; Im, Hong G.

doi:10.1016/j.combustflame.2021.111523

Cited by 27 publications

(23 citation statements)

References 57 publications

(84 reference statements)

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“…All the cases are either in, or very close to, the thin reaction zones regime. It has been noted that broken reaction zones are not observed even well beyond Ka=100 (Aspden et al 2019;Song et al 2021), which was also found to be true for all of the present cases. In all cases, the turbulent flame approached a statistically stationary state, albeit with considerable fluctuations of s T about its mean value, as observed in other work (Poludnenko and Oran 2011;Lipatnikov et al 2015).…”

Section: Dns Dataset For the Current Studysupporting

confidence: 84%

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Turbulence Intensity and Length Scale Effects on Premixed Turbulent Flame Propagation

Trivedi

Cant

2021

Flow Turbulence Combust

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The effects of varying turbulence intensity and turbulence length scale on premixed turbulent flame propagation are investigated using Direct Numerical Simulation (DNS). The DNS dataset contains the results of a set of turbulent flame simulations based on separate and systematic changes in either turbulence intensity or turbulence integral length scale while keeping all other parameters constant. All flames considered are in the thin reaction zones regime. Several aspects of flame behaviour are analysed and compared, either by varying the turbulence intensity at constant integral length scale, or by varying the integral length scale at constant turbulence intensity. The turbulent flame speed is found to increase with increasing turbulence intensity and also with increasing integral length scale. Changes in the turbulent flame speed are generally accounted for by changes in the flame surface area, but some deviation is observed at high values of turbulence intensity. The probability density functions (pdfs) of tangential strain rate and mean flame curvature are found to broaden with increasing turbulence intensity and also with decreasing integral length scale. The response of the correlation between tangential strain rate and mean flame curvature is also investigated. The statistics of displacement speed and its components are analysed, and the findings indicate that changes in response to decreasing integral length scale are broadly similar to those observed for increasing turbulence intensity, although there are some interesting differences. These findings serve to improve current understanding of the role of turbulence length scales in flame propagation.

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Section: Dns Dataset For the Current Studysupporting

confidence: 84%

“…There have been fewer studies which have produced information about the effect on the flame of varying the turbulence integral length scale l 0 (Peters 1999;Lipatnikov and Chomiak 1999;Song et al 2021). Several experimental investigations dealing with variations in 0 have been discussed in Sect.…”

Section: Introductionmentioning

confidence: 99%

Turbulence Intensity and Length Scale Effects on Premixed Turbulent Flame Propagation

Trivedi

Cant

2021

Flow Turbulence Combust

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“…Attili et al [15] and Wang et al [16] investigated flame structures for premixed jet flames that eventually led to the enhancement of S d at moderate and high Ka. A number of "flame-in-the-box" simulations by Hamlington et al [17], Poludnenko and Oran [18,19], Song et al [20], Lipatnikov et al [21] explored a wide range of Ka conditions reaching up to thin reaction zone and distributed regimes, and reported that even the strong turbulence broadened the preheat zone only while the main reaction zones remained intact. It was found that the global acceleration of the flame was obtained as a combined effect of an increase in the flame surface area along with flameflame collision and large flame curvature [19,20].…”

Section: Introductionmentioning

confidence: 99%

“…A number of "flame-in-the-box" simulations by Hamlington et al [17], Poludnenko and Oran [18,19], Song et al [20], Lipatnikov et al [21] explored a wide range of Ka conditions reaching up to thin reaction zone and distributed regimes, and reported that even the strong turbulence broadened the preheat zone only while the main reaction zones remained intact. It was found that the global acceleration of the flame was obtained as a combined effect of an increase in the flame surface area along with flameflame collision and large flame curvature [19,20]. For detailed insights into preheat zone structure at high Ka turbulence, the readers could refer to the recent review by Driscoll et al [22].…”

Section: Introductionmentioning

confidence: 99%

“…In view of the above developments, the present study undertakes the detailed analysis using a recent DNS dataset [20] covering a large range of Ka and Re t , in order to assess the validity of the interaction model at high Ka ∼ O(1000) conditions. The DNS data correspond to different turbulent combustion regimes for a H 2 -air premixed flame: two in broken reaction regime and two in thin reaction regime.…”

Section: Introductionmentioning

confidence: 99%

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Local flame displacement speeds of hydrogen-air premixed flames in moderate to intense turbulence

Song,

Dave,

et al. 2021

Preprint

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Comprehensive knowledge of local flame displacement speed, S d , in turbulent premixed flames is crucial towards the design and development of hydrogen fuelled next-generation engines. Premixed hydrogen-air flames are characterized by significantly higher laminar flame speed compared to other conventional fuels. Furthermore, in the presence of turbulence, S d is enhanced much beyond its corresponding unstretched, planar laminar value S L . In this study, the effect of high Karlovitz number (Ka) turbulence on densityweighted flame displacement speed, S d , in a H 2 -air flame is investigated. Recently, it has been identified that flame-flame interactions in regions of large negative curvature govern large deviations of S d from S L , for moderately turbulent flames. An interaction model for the same has also been proposed. In this work, we seek to test the interaction model's applicability to intensely turbulent flames characterized by large Ka. To that end, we investigate the local flame structures: thermal, chemical structure, the effect of curvature, along the direction that is normal to the chosen isothermal surfaces. Furthermore, relative contributions of the transport and chemistry terms to S d are also analyzed. It is found that, unlike the moderately turbulent premixed flames, where enhanced S d is driven by interactions among complete flame structures, S d enhancement in high Re t and high Ka flame is predominantly governed by local interactions of the isotherms.

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Turbulent Hydrogen Flames: Physics and Modeling Implications

Song

Pérez

2023

Hydrogen for Future Thermal Engines

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Statistics of local and global flame speed and structure for highly turbulent H2/air premixed flames

Cited by 27 publications

References 57 publications

Turbulence Intensity and Length Scale Effects on Premixed Turbulent Flame Propagation

Turbulence Intensity and Length Scale Effects on Premixed Turbulent Flame Propagation

Local flame displacement speeds of hydrogen-air premixed flames in moderate to intense turbulence

Turbulent Hydrogen Flames: Physics and Modeling Implications

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