Statistics of progress variable and mixture fraction gradients in an open turbulent jet spray flame

d’Auzay, Charles Turquand; Ahmed, Umair; Pillai, Abhishek L.; Chakraborty, Nilanjan; Kurose, Ryoichi

doi:10.1016/j.fuel.2019.02.111

Cited by 14 publications

(7 citation statements)

References 48 publications

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“…The simulation has been performed using the code known as FK 3 , which has been used in several previous studies on turbulent, reacting, and multiphase flows. [27][28][29][30][31] The code solves conservation equations for mass, momentum, enthalpy, and chemical species in the context of the finite volume framework. A skeletal chemical mechanism comprising nine chemical species and twenty reactions 32 is used to represent hydrogen-air combustion.…”

Section: Direct Numerical Simulation Datamentioning

confidence: 99%

Surface density function evolution and the influence of strain rates during turbulent boundary layer flashback of hydrogen-rich premixed combustion

et al. 2020

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The statistical behavior of the magnitude of the reaction progress variable gradient [alternatively known as the surface density function (SDF)] and the strain rates, which govern the evolution of the SDF, have been analyzed for boundary layer flashback of a premixed hydrogen-air flame with an equivalence ratio of 1.5 in a fully developed turbulent channel flow. The non-reacting part of the channel flow is representative of the friction velocity based Reynolds number Reτ = 120. A skeletal chemical mechanism with nine chemical species and twenty reactions is employed to represent hydrogen-air combustion. Three definitions of the reaction progress variable (RPV) based on the mass fractions of H 2 , O 2 , and H 2 O have been considered to analyze the SDF statistics. It is found that the mean variations of the SDF and the displacement speed S d depend on the choice of the RPV and the distance away from the wall. The preferential alignment of the RPV gradient with the most extensive principal strain rate strengthens with an increase in distance from the cold wall, which leads to changes in the behaviors of normal and tangential strain rates from the vicinity of the wall toward the middle of the channel. The differences in displacement speed statistics for different choices of the RPV and the wall distance affect the behaviors of the normal strain rate due to flame propagation and curvature stretch. The relative thickening/thinning of the reaction layers of the major species has been explained in terms of the statistics of the effective normal strain rate experienced by the progress variable isosurfaces for different wall distances and choices of RPVs.

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Section: Direct Numerical Simulation Datamentioning

confidence: 99%

Surface density function evolution and the influence of strain rates during turbulent boundary layer flashback of hydrogen-rich premixed combustion

et al. 2020

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“…In terms of generality of the present study, it should further be noted that in turbulent premixed flames, SDR models calibrated for statistically planar flames have been found to remain valid for relatively complex geometrical configurations (Gao and Chakraborty 2016) and that the statistics of mixture fraction gradients in statistically planar turbulent spray flames (Wacks and Chakraborty 2016) are qualitatively similar in planar spray jets (Turquand-d'Auzay et al 2019b). This inspires confidence that the modelling conclusions drawn in this analysis are unlikely to change in another configuration provided the mean curvature of that configuration remains small.…”

Section: Dns Datasetmentioning

confidence: 58%

A-Priori Validation of Scalar Dissipation Rate Models for Turbulent Non-Premixed Flames

Sitte

Turquand

Giusti

et al. 2020

Flow Turbulence Combust

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The modelling of scalar dissipation rate in conditional methods for large-eddy simulations is investigated based on a priori direct numerical simulation analysis using a dataset representing an igniting non-premixed planar jet flame. The main objective is to provide a comprehensive assessment of models typically used for large-eddy simulations of non-premixed turbulent flames with the Conditional Moment Closure combustion model. The linear relaxation model gives a good estimate of the Favre-filtered scalar dissipation rate throughout the ignition with a value of the related constant close to the one deduced from theoretical arguments. Such value of the constant is one order of magnitude higher than typical values used in Reynolds-averaged approaches. The amplitude mapping closure model provides a satisfactory estimate of the conditionally filtered scalar dissipation rate even in flows characterised by shear driven turbulence and strong density variation.

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“…It should be noted that the DNS simulation results have been compared against the experimental data of Gounder et al [14] at different axial distances from the nozzle [23]. Good agreement has been found between the experimental and computational results, and the interested readers are referred to [23,39] for a detailed discussion of these results which will not be repeated here for the sake of brevity.…”

Section: (A) (B)mentioning

confidence: 85%

“…In the current analysis, the DNS data analysed has been obtained by Pillai and Kurose [22,23] using the FK 3 code [22,23,[34][35][36][37][38][39][40][41][42]. The liquid spray fuel is Ethanol (C 2 H 5 OH) and a two-step global reaction mechanism with 6 species (C 2 H 5 OH, O 2 , CO 2 , H 2 O, N 2 and CO) is considered for representing combustion process [43] to ensure computational economy.…”

Section: Relevant Mathematical Backgroundmentioning

confidence: 99%

“…In order to guarantee an appropriate resolution of both the turbulence and the premixed flame front, the smallest cell size at the nozzle exit is ∆𝑥 = 150𝜇𝑚. For interested readers, further details on the boundary conditions and computational grid can be found in [22,23,39]. The integral length-scale and velocity fluctuations are evaluated within the shear layer and are reported in Fig.…”

Section: (A) (B)mentioning

confidence: 99%

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Displacement speed statistics in an open turbulent jet spray flame

Malkeson

Ahmed

d’Auzay

et al. 2021

Fuel

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Statistics of progress variable and mixture fraction gradients in an open turbulent jet spray flame

Cited by 14 publications

References 48 publications

Surface density function evolution and the influence of strain rates during turbulent boundary layer flashback of hydrogen-rich premixed combustion

Surface density function evolution and the influence of strain rates during turbulent boundary layer flashback of hydrogen-rich premixed combustion

A-Priori Validation of Scalar Dissipation Rate Models for Turbulent Non-Premixed Flames

Displacement speed statistics in an open turbulent jet spray flame

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