Local Flame Structure in Hydrogen-Air Turbulent Premixed Flames

Tanahashi, Mamoru; Fujimura, Masanari; Miyauchi, Toshio

doi:10.1007/978-94-017-1998-8_22

Cited by 3 publications

(7 citation statements)

References 3 publications

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“…Also, there are regions of high positive curvature (convex to the reactant side) trying to advance into the reactants (3rd frame in Figure 9 and 2nd frame in Figure 10), which eventually break apart due to excessive heat losses. It is found that heat release is maximized in negatively curved regions for both cases, consistent with previous studies of methane-air (Echekki and Chen, 1996) and hydrogen-air (Tanahashi et al, 1999) combustion. A stoichiometric hydrogen-air flame with u rms;in s l ¼ 3:41, l int;in δ l ¼ 0:85 and T r = 700 K was simulated by Tanahashi et al (1999), using a detailed mechanism and these conditions are similar to the inlet conditions for case A.…”

Section: Dns Of Fuel Combustion With Detailed Chemistrysupporting

confidence: 91%

“…The turbulent kinetic energy dissipation rate is high at the inlet and so the initial laminar flame interacts with a relatively weaker turbulence than at the inlet. This cannot be avoided in simulations of this kind (Sankaran et al, 2006;Tanaka et al, 2011;Tanahashi et al, 1999;Thévenin et al, 2002), unless the turbulence Reynolds number, Re t ¼ u rms l int =v r , where v r is the kinematic viscosity of reactant mixture, is sufficiently low or turbulence is forced and these approaches have their own disadvantages.…”

Section: Flow Configuration and Boundary Conditionsmentioning

confidence: 99%

“…These studies were predominantly for 2D turbulent combustion of hydrogen air (Baum et al, 1992(Baum et al, , 1994Chen and Im, 2000;Im and Chen, 2002;Lange et al, 1998) and methane-air (Chen et al, 1999;Domingo et al, 2005;Echekki and Chen, 1999;Gran et al, 1996;Chen, 2004, 2006;Kaminski et al, 2000;Peters et al, 1998) mixtures. There were some 3D direct simulations of premixed hydrogen (Hawkes et al, 2012;Tanahashi et al, 1999Tanahashi et al, , 2002Tanaka et al, 2011) and methane (Bell et al, 2002;Sankaran et al, 2006;Thévenin et al, 2002) combustion. Non-premixed combustion of a hydrogen jet issuing into still air has also been simulated in 3D (Mizobuchi et al, 2002(Mizobuchi et al, , 2005.…”

Section: Introductionmentioning

confidence: 99%

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Direct Numerical Simulation of Complex Fuel Combustion with Detailed Chemistry: Physical Insight and Mean Reaction Rate Modeling

Nikolaou

Swaminathan

2015

Combustion Science and Technology

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Direct numerical simulation (DNS) of freely-propagating premixed flames of a multicomponent fuel is performed using a skeletal chemical mechanism with 49 reactions and 15 species. The fuel consists of CO, H 2 , H 2 O, CH 4 , and CO 2 in proportions akin to blast furnace gas or a low calorific value syngas. The simulations include low and high turbulence levels to elucidate the effect of turbulence on realistic chemistry flames. The multi-component fuel flame is found to have a more complex structure than most common flames, with individual species' reaction zones not necessarily overlapping with each other and with a wide heat releasing zone. The species mass fractions and heat release rate show significant scatter, with their conditional average however remaining close to the laminar flame result. Probability density functions of displacement speed, stretch rate, and curvature are near-Gaussian. Five different mean reaction rate closures are evaluated in the RANS context using these DNS data, presenting perhaps the most stringent test to date of the combustion models. Significant quantitative differences are observed in the performance of the models tested, especially for the higher turbulence level case.

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Section: Dns Of Fuel Combustion With Detailed Chemistrysupporting

confidence: 91%

Section: Flow Configuration and Boundary Conditionsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Direct Numerical Simulation of Complex Fuel Combustion with Detailed Chemistry: Physical Insight and Mean Reaction Rate Modeling

Nikolaou

Swaminathan

2015

Combustion Science and Technology

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“…However, for methane-air flame, they show relatively strong correlation. The reasons of these different correlations have been discussed based on elementary reactions and diffusivity of major atoms (46), (47) . The heat release rates tend to increase from C-C regime to S-S regime.…”

Section: Journal Of Thermal Science and Technologymentioning

confidence: 99%

DNS and Combined Laser Diagnostics of Turbulent Combustion

Tanahashi

Sato

Shimura

et al. 2008

JTST

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With the developments of computer technologies, three-dimensional direct numerical simulations (DNS) of turbulent combustion have been realized with a detailed or reduced kinetic mechanism. The 3D DNS gives detailed information about turbulent flames, while there are few experimental techniques which have high accuracy enough to compare with DNS. In this paper, after showing summary of recent DNS of turbulent premixed flames, newly-developed laser diagnostics are presented. Simultaneous CH-OH planar laser induced fluorescence (PLIF) and stereoscopic particle image velocimetry (PIV) are used to investigate the local flame structure of the turbulent premixed flames. From CH-OH PLIF and PIV measurements, flame fronts are identified, and the curvature of the flame front and the tangential strain rate at the flame front are evaluated. The experimental results are compared with 3D DNS of hydrogen-air and methane-air turbulent premixed flames. The flame displacement speeds in turbulent premixed flames have been measured directly by the CH double-pulsed PLIF. Since the time interval of the successive CH PLIF can be selected arbitrarily, both of the large scale dynamics and local displacement of the flame front can be obtained. As an application of laser diagnostics for development of high-efficient and low-emission combustors, reconstruction of 3D flame structure is shown by using multiple-plane OH PLIF.

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“…Moreover, in turbulent premixed flames, for example, the increment in flame velocity is larger than that in the flamesurface area at Lewis numbers lower than unity 30,31) and at lean hydrogen-air mixtures. 32) Thus we need to consider not only the flame-surface area, but also the Lewis-number effect in studying flame velocity.…”

Section: Introductionmentioning

confidence: 99%

Formation of Cellular Flames and Increase in Flame Velocity Generated by Intrinsic Instability.

Kadowaki

2002

Trans. Japan Soc. Aero. S Sci.

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The formation of cellular flames and the increase in flame velocity generated by intrinsic instability are studied by two-dimensional (2-D) and three-dimensional (3-D) unsteady calculations of reactive flows based on the compressible Navier-Stokes equation. We consider three basic types of phenomena to be responsible for the intrinsic instability of premixed flames, i.e., hydrodynamic, diffusive-thermal, and body-force instabilities. Cellular flames are generated by intrinsic instability, and thus the flame-surface area becomes larger and the flame velocity increases. The increment in flame velocity of 3-D flames is about twice that of 2-D flames, since the increment in flame-surface area of the former is about twice that of the latter. This relationship is due to the difference in the disposition of cells between 2-D and 3-D flames. When the Lewis number is lower than unity, i.e., when diffusive-thermal instability appears, the increment in flame velocity is larger than in the flame-surface area. This is because the increase in the local consumption rate of the unburned gas at a convex flame surface exceeds the decrease at a concave one. When the Lewis number is unity, i.e., when hydrodynamic and body-force instabilities are dominant, the flame velocity is nearly proportional to the flame-surface area, since the local consumption rate is nearly constant.

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Local Flame Structure in Hydrogen-Air Turbulent Premixed Flames

Cited by 3 publications

References 3 publications

Direct Numerical Simulation of Complex Fuel Combustion with Detailed Chemistry: Physical Insight and Mean Reaction Rate Modeling

Direct Numerical Simulation of Complex Fuel Combustion with Detailed Chemistry: Physical Insight and Mean Reaction Rate Modeling

DNS and Combined Laser Diagnostics of Turbulent Combustion

Formation of Cellular Flames and Increase in Flame Velocity Generated by Intrinsic Instability.

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