Entropy Generation during Head-On Interaction of Premixed Flames with Inert Walls within Turbulent Boundary Layers

Ghai, Sanjeev Kumar; Ahmed, Umair; Chakraborty, Nilanjan; Klein, Markus

doi:10.3390/e24040463

Cited by 8 publications

(3 citation statements)

References 43 publications

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“…The solution of all of these aforementioned equations with DNS was performed in configurations without considering the presence of the walls [ 20 , 27 ]. Only recently, the effect of the wall was accounted for in [ 108 ] where the authors investigated the entropy production in the head-on interaction of turbulent premixed flames with an isothermal and chemically inert wall within turbulent boundary layers.…”

Section: Entropy Generation Analysis Using Dnsmentioning

confidence: 99%

“…This was achieved by Salimath et al [ 109 ] who investigated the wall effect on the entropy production in a 1D laminar flame propagating towards and quenching at a either solid or permeable wall. Recently, Ghai et al [ 108 ] examined the entropy production behavior in a head-on interaction of turbulent premixed methane-air flame with a chemically inert wall.…”

Section: Entropy Generation Analysis Using Dnsmentioning

confidence: 99%

“…Moreover, in the isothermal case, the entropy generation due to thermal diffusion during the FWI is relatively higher compared to the adiabatic case in which the mean values of entropy generation due to thermal diffusion and molecular mixing have small values near the wall. Through their analysis, Ghai et al [ 108 ] revealed the importance of the wall boundary conditions in the irreversibilities reduction and the thermodynamic performance optimization in combustion systems.…”

Section: Entropy Generation Analysis Using Dnsmentioning

confidence: 99%

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Entropy Generation Analysis in Turbulent Reacting Flows and Near Wall: A Review

Sadiki

Agrebi

Ries

2022

Entropy

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This paper provides a review of different contributions dedicated thus far to entropy generation analysis (EGA) in turbulent combustion systems. We account for various parametric studies that include wall boundedness, flow operating conditions, combustion regimes, fuels/alternative fuels and application geometries. Special attention is paid to experimental and numerical modeling works along with selected applications. First, the difficulties of performing comprehensive experiments that may support the understanding of entropy generation phenomena are outlined. Together with practical applications, the lumped approach to calculate the total entropy generation rate is presented. Apart from direct numerical simulation, numerical modeling approaches are described within the continuum formulation in the framework of non-equilibrium thermodynamics. Considering the entropy transport equations in both Reynolds-averaged Navier–Stokes and large eddy simulation modeling, different modeling degrees of the entropy production terms are presented and discussed. Finally, exemplary investigations and validation cases going from generic or/and canonical configurations to practical configurations, such as internal combustion engines, gas turbines and power plants, are reported. Thereby, the areas for future research in the development of EGA for enabling efficient combustion systems are highlighted. Since EGA is known as a promising tool for optimization of combustion systems, this aspect is highlighted in this work.

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Section: Entropy Generation Analysis Using Dnsmentioning

confidence: 99%

Section: Entropy Generation Analysis Using Dnsmentioning

confidence: 99%

Section: Entropy Generation Analysis Using Dnsmentioning

confidence: 99%

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Entropy Generation Analysis in Turbulent Reacting Flows and Near Wall: A Review

Sadiki

Agrebi

Ries

2022

Entropy

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Effects of Fuel Lewis Number on Wall Heat Transfer During Oblique Flame-Wall Interaction of Premixed Flames Within Turbulent Boundary Layers

Ghai

Ahmed

Chakraborty

2023

Flow Turbulence Combust

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The influence of fuel Lewis number $${\mathrm{Le}}_{F}$$ Le F on the statistical behaviour of wall heat flux and flame quenching distance has been analysed using direct numerical simulation (DNS) data for the turbulent V-shaped flame-wall interaction in a channel flow configuration corresponding to a friction velocity-based Reynolds number of 110 for fuel Lewis number, $${\mathrm{Le}}_{F}$$ Le F , ranging from 0.6 to 1.4. It has been found that the maximum wall heat flux magnitude in turbulent V-shaped flame-wall interaction increases with decreasing $${\mathrm{Le}}_{F}$$ Le F but just the opposite trend was observed for 2D laminar V-shaped flame-wall interaction and 1D laminar head-on quenching cases. This behaviour has been explained in terms of the correlation of temperature and fuel reaction rate magnitude with local flame surface curvature for turbulent flames due to the thermo-diffusive effects induced by the non-unity Lewis number. The wall heat flux magnitude and wall shear stress magnitude are found to be negatively correlated for all cases considered here. Moreover, their mean variations in the streamwise direction are qualitatively different irrespective of $${\mathrm{Le}}_{F}$$ Le F , although the magnitudes of wall heat flux and wall shear stress increase with decreasing $${\mathrm{Le}}_{F}$$ Le F . Furthermore, the flame alignment relative to the wall also affects the wall heat flux and it has been found that local occurrences of head-on quenching can lead to higher magnitudes of wall heat flux magnitude. It has been found that $${\mathrm{Le}}_{F}$$ Le F also affects the evolution of the flame quenching distance in the streamwise direction with the progress of flame quenching for different flame normal orientations with respect to the wall. This analysis shows that the effects of fuel Lewis number on flame orientation, correlations of reaction rate and temperature with local flame curvature and coherent flow structures within the turbulent boundary layer ultimately affect the wall heat transfer and flame quenching distance. Thus, the thermo-diffusive effects arising from the non-unity Lewis number need to be taken into account for accurate modelling of wall heat transfer during flame-wall interaction in turbulent boundary layers.

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Statistical Behaviour and Modelling of Variances of Reaction Progress Variable and Temperature During Flame-Wall Interaction of Premixed Flames Within Turbulent Boundary Layers

Ghai

Ahmed

Chakraborty

2023

Flow Turbulence Combust

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The statistical behaviour of the transport of reaction progress variable variance, $$\widetilde{{c^{^{\prime\prime}2} }},$$ c ″ 2 ~ , and non-dimensional temperature variance, $$\widetilde{{T^{^{\prime\prime}2} }},$$ T ″ 2 ~ , have been analysed using three-dimensional Direct Numerical Simulation (DNS) data of turbulent premixed flame-wall interaction with isothermal inert walls within turbulent boundary layers for (i) an unsteady head-on quenching of a statistically planar flame propagating across the boundary layer, and (ii) a statistically stationary oblique wall quenching of a V-flame. It has been found that the reaction rate contribution acts as a leading order source term to the transport of both reaction progress variable variance, $$\widetilde{{c^{^{\prime\prime}2} }},$$ c ″ 2 ~ , and non-dimensional temperature variance, $$\widetilde{{T^{^{\prime\prime}2} }},$$ T ″ 2 ~ , whereas the molecular dissipation term remains the leading order sink term for both configurations analysed here. With the progress of flame wall interaction, the magnitude of all the source terms for the transport equations of both reaction progress variable and non-dimensional temperature variances vanish in the near-wall region with the onset of flame quenching. However, the molecular dissipation term continues to act as a sink term. The performances of the existing models for turbulent scalar flux, reaction rate and scalar dissipation rate contributions have been assessed for both flame-wall interaction configurations based on a priori DNS analysis. The existing available models for scalar dissipation rate for temperature and the reaction rate contribution in the variance transport equations even with the previously proposed wall corrections do not adequately predict the behaviour in the near-wall region. Modifications have been suggested to the existing closure models for the scalar dissipation rate and the reaction rate contribution to the scalar variance transport equations to improve the predictions in the near-wall region. Furthermore, the recommended closures for the unclosed terms of both reaction progress variable variance, $$\widetilde{{c^{^{\prime\prime}2} }},$$ c ″ 2 ~ , and non-dimensional temperature variance, $$\widetilde{{T^{^{\prime\prime}2} }},$$ T ″ 2 ~ , are shown to accurately capture the corresponding variations obtained from DNS data for both near to and away from the wall.

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Entropy Generation during Head-On Interaction of Premixed Flames with Inert Walls within Turbulent Boundary Layers

Cited by 8 publications

References 43 publications

Entropy Generation Analysis in Turbulent Reacting Flows and Near Wall: A Review

Entropy Generation Analysis in Turbulent Reacting Flows and Near Wall: A Review

Effects of Fuel Lewis Number on Wall Heat Transfer During Oblique Flame-Wall Interaction of Premixed Flames Within Turbulent Boundary Layers

Statistical Behaviour and Modelling of Variances of Reaction Progress Variable and Temperature During Flame-Wall Interaction of Premixed Flames Within Turbulent Boundary Layers

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