Turbulent Flame Structure of Methane-Hydrogen Mixtures at Elevated Temperature and Pressure

Bagdanavičius, Audrius; Bowen, Philip John; Syred, N.; Crayford, Andrew Philip

doi:10.1080/00102202.2012.718005

Cited by 9 publications

(2 citation statements)

References 25 publications

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“…Subsequent comparisons showed the burner flame front location to be consistently close to = 0.5, which defines the surface area appropriate to the mass burning rate on burners [18]. More details of the image processing are available in [21]. Values of k were found between = 0.2 and 0.8, over which range they remained fairly constant.…”

Section: High Pressure Burner Experimentsmentioning

confidence: 83%

Stretch rate effects and flame surface densities in premixed turbulent combustion up to 1.25 MPa

Bagdanavičius

Bowen

Bradley

et al. 2015

Combustion and Flame

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Key wordsTurbulent premixed flame, burning velocity, flame stretch rate, flame surface density, Markstein number. AbstractIndependent research at two centres using a burner and an explosion bomb has revealed important aspects of turbulent premixed flame structure. Measurements at pressures and temperatures up to 1.25 MPa and 673 K in the two rigs were aimed at quantifying the influences of flame stretch rate and strain rate Markstein number, Ma sr , on both turbulent burning velocity and flame surface density. That on burning velocity is expressed through the stretch rate factor, I o , or probability of burning, P b 0.5 . These depend on Ma sr , but they grow in importance as the Karlovitz stretch factor, K, increases, and are evaluated from the associated burning velocity data. Planar laser tomography was employed to identify contours of reaction progress variable in both rigs. These enabled both an appropriate flame front for the measurement of the turbulent burning velocity to be identified, and flame surface densities, with the associated factors, to be evaluated. In the explosion measurements, these parameters were derived also from the flame surface area, the derived P b 0.5 factor and the measured turbulent burning velocities. In the burner measurement they were calculated directly from the flame surface density, which was derived from the flame contours.A new overall correlation is derived for the P b 0.5 factor, in terms of Ma sr at different K and this is discussed in the light of previous theoretical studies. The wrinkled flame surface area normalised by the area associated with the turbulent burning velocity measurement, and the ratio of turbulent to laminar burning velocity, u t /u l , are also evaluated. The higher the value of , the more effective is an increased flame wrinkling in increasing u t /u l . A correlation of the product of k and the laminar flame thickness with Karlovitz stretch factor and Markstein number is explored using the present data and those of other workers. Some generality is revealed, enabling the wave length associated with the spatial change in mean reaction progress variable to be expressed by the number of laminar flame thicknesses, and the flame volume to be found.

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Section: High Pressure Burner Experimentsmentioning

confidence: 83%

Stretch rate effects and flame surface densities in premixed turbulent combustion up to 1.25 MPa

Bagdanavičius

Bowen

Bradley

et al. 2015

Combustion and Flame

Self Cite

View full text Add to dashboard Cite

show abstract

“…Optical diagnostics have provided details on the combustion behaviors, efficiencies, and emissions of these mixtures (Mashruk et al 2023;Marsh et al 2017). The feasibility of 100% ammonia combustion has been analyzed (Bagdanavicius et al 2013). Flame structure and particulate emissions have been characterized for biodiesel and biogas (Kurji et al 2016;Buffi et al 2017).…”

Section: C) Alternative Fuels Researchmentioning

confidence: 99%

Numerical Simulation of Turbulent Premixed CH4-H2 Flames in a High Pressure Swirl Burner for Gas Turbine Applications

ouali

2024

Preprint

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This 3D numerical study investigates the combustion characteristics of methane-hydrogen blends in a high-pressure swirl burner for gas turbine applications. Hydrogen concentration is varied from 0% to 50% in steps of 5 % by volume for four thermal power levels (42KW, 84 KW, 126 KW, and 168 kW). The other parameters such as the inlet temperature as well as the fuel-air ratio were kept constant in order to analyze only the effect of the H2 addition and the power variation. Results demonstrate hydrogen enrichment mildly increases flame temperature and stabilizes the reaction zone without significantly disturbing the flow field. All cases exhibit coherent temperature evolution and steady flame fronts. NOx production shows an acceptable rise with hydrogen addition peaking at 6.2 ppm for 168 KW power and 50 % of H2. Results suggest this burner geometry can stably operate on methane-hydrogen mixtures up to 50% by volume hydrogen across a wide power band, offering promising prospects for gas turbine fuel flexibility.

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Effects of Pressure and Characteristic Scales on the Structural and Statistical Features of Methane/Air Turbulent Premixed Flames

Bowers,

Durant,

Ranjan

2024

Flow Turbulence Combust

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In this study, the highly nonlinear and multi-scale flame-turbulence interactions prevalent in turbulent premixed flames are examined by using direct numerical simulation (DNS) datasets to understand the effects of increase in pressure and changes in the characteristic scale ratios at high pressure. Such flames are characterized by length-scale ratio (ratio of integral length scale and laminar thermal flame thickness) and velocity-scale ratio (ratio of turbulence intensity and laminar flame speed). A canonical test configuration corresponding to an initially laminar methane/air lean premixed flame interacting with decaying isotropic turbulence is considered. We consider five cases with the initial Karlovitz number of 18, 37, 126, and 260 to examine the effects of an increase in pressure from 1 to 10 atm with fixed turbulence characteristics and at a fixed Karlovitz number, and the changes to characteristic scale ratios at the pressure of 10 atm. The increase in pressure for fixed turbulence characteristics leads to enhanced flame broadening and wrinkling due to an increase in the range of energetic scales of motion. This further manifests into affecting the spatial and state-space variation of thermo-chemical quantities, single point statistics, and the relationship of heat-release rate to the flame curvature and tangential strain rate. Although these results can be inferred in terms of an increase in Karlovitz number, the effect of an increase in pressure at a fixed Karlovitz number shows differences in the spatial and state-space variations of thermo-chemical quantities and the relationship of the heat release rate with the curvature and tangential strain rate. This is due to a higher turbulent kinetic energy associated with the wide range of scales of motion at atmospheric pressure. In particular, the magnitude of the correlation of the heat release rate with the curvature and the tangential strain rate tend to decrease and increase, respectively, with an increase in pressure. Furthermore, the statistics of the flame-turbulence interactions at high pressure also show sensitivity to the changes in the characteristic length- and velocity-scale ratios. The results from this study highlight the need to accurately account for the effects of pressure and characteristic scales for improved modeling of such flames.

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Turbulent Flame Structure of Methane-Hydrogen Mixtures at Elevated Temperature and Pressure

Cited by 9 publications

References 25 publications

Stretch rate effects and flame surface densities in premixed turbulent combustion up to 1.25 MPa

Stretch rate effects and flame surface densities in premixed turbulent combustion up to 1.25 MPa

Numerical Simulation of Turbulent Premixed CH4-H2 Flames in a High Pressure Swirl Burner for Gas Turbine Applications

Effects of Pressure and Characteristic Scales on the Structural and Statistical Features of Methane/Air Turbulent Premixed Flames

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