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Abtahizadeh, Ebrahim; Goey, de Lph Philip; Oijen, van Ja Jeroen

doi:10.1016/j.fuel.2016.11.054

Cited by 27 publications

(9 citation statements)

References 39 publications

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“…The axisymmetric boundary condition imposed on the center line of the present study might be responsible for partial over-prediction of temperature fluctuations in the mixing shear layer. In the thermal shear layer, it can be seen that the second peak is under-estimated by about 200 K in previous works [19,22]. Unlike the previous studies, the magnitude of the second peak at = 30 and 60 mm, is properly captured by the DKE SGS model.…”

Section: Effect Of Sgs Models On Statistical Temperature Fieldcontrasting

confidence: 57%

“…Predicted peak value of the combined shear layer at downstream = 120 is also slightly improved rather than the numerical results of previous studies. The peak positions are slightly over-estimated especially at upstream, as observed in similar studies [19] which the reason is not clear yet. It should be noted that improved results of temperature fluctuations in the present study have been obtained using the simple FR/ED combustion model coupled with a global three-step chemical mechanism.…”

Section: Effect Of Sgs Models On Statistical Temperature Fieldmentioning

confidence: 51%

“…They demonstrated that preferential diffusion has a significant influence on the lift-off height and stabilization mechanism of the lifted H2-enriched turbulent flames. They also observed some discrepancies of velocity fluctuations in the transition region of the fuel jet stream and referred them to the inaccurate Smagorinsky SGS model [19]. Impact of SGS models on resolving characteristics of swirling diffusion flames was studied later by the Hu et al [20].…”

Section: Introductionmentioning

confidence: 98%

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Impact of sub-grid scale models on resolving mixing and thermal shear layers in large eddy simulation of JHC flames

Aminian

Galletti

Tognotti

2019

Applied Thermal Engineering

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Predictive performance of sub-grid scale (SGS) models is investigated in Large Eddy Simulation (LES) of a methane/hydrogen jet-in-hot coflow (JHC) flame using a conceptual analysis proposed for the mean values of major combustion products. It is shown that mean values of major combustion products consist of valuable information on several characteristics of JHC flames such as flame thickness, flame volume and reaction intensity. In particular, sudden change of CO 2 and H 2 O mass fractions from coflow contents to higher values, predicted by static SGS models, demonstrated a thin flame constricted around the center line. However, uniform ascending manner of CO 2 and H 2 O contents in the coflow region predicted by dynamic SGS models revealed their ability on capturing characteristics of a distributed volumetric flame. For the temperature fluctuations in shear layers, the dynamic Smagorinsky model is also shown to provide better predictions than the constant-coefficient Smagorinsky model, the latter exhibiting significant over-predictions. It is also observed that the dynamic kinetic energy SGS model with its unique assumption of non-equilibrium turbulence is the best fitted SGS model for the JHC

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Section: Effect Of Sgs Models On Statistical Temperature Fieldcontrasting

confidence: 57%

Section: Effect Of Sgs Models On Statistical Temperature Fieldmentioning

confidence: 51%

Section: Introductionmentioning

confidence: 98%

See 1 more Smart Citation

Impact of sub-grid scale models on resolving mixing and thermal shear layers in large eddy simulation of JHC flames

Aminian

Galletti

Tognotti

2019

Applied Thermal Engineering

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“…The effect of the SGS variance of the progress variable was ignored by assuming that the shape of the PDF could be represented by the δ-function. Although the SGS variance of the progress variable has a significant effect on calculations performed for limited domains [45][46][47], the effect should be small in the case of a stable flame, as was the case in the investigated domain.…”

Section: Computational Domain and Numerical Conditionsmentioning

confidence: 88%

Effects of infinitely fast chemistry on combustion behavior of coaxial diffusion flame predicted by large eddy simulation

Akaotsu

Ozawa

Matsushita

et al. 2020

Fuel Processing Technology

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Large eddy simulations (LES) based on turbulent combustion models aid the design and optimization of combustors. Of the various combustion models available, the eddy break up (EBU) model is widely used because it assumes an infinitely fast chemistry. However, omitting the actual chemical kinetics can cause unexpected behavior, and the characteristics of the combustion models need to be elucidated. Here, the effects of an infinitely fast chemistry on the combustion behavior of a coaxial diffusion flame as predicted by an LES were analyzed. Although the EBU model captured the overall behavior of the chemical species as well as the flow field, the gas temperature and mass fractions of the combustion products in the mixing region of the fuel and oxidizer streams were overestimated. In contrast, the flamelet/progress variable (FPV) model yielded results that were in better agreement with the experimental data, because while the EBU model assumes an infinitely fast chemistry, the look-up tables used in the FPV model are based on the actual chemical kinetics. As these models can be used for the CFD simulations of coal and spray combustion, the results of this study should be useful for efficiently simulating practical combustion systems.

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“…And finally, auto-ignition of spray is investigated in [24,25,29,43,56,60,61,74,94,105]. Related approaches for auto-ignition modeling are the flamelet-generated-manifolds (FGM) [1,2,13,14,29,36,42], the flame prolongation of intrinsic low-dimensional manifolds (FPI) [26], and the approximated diffusion flame-presumed conditional moment (ADF-PCM) method [66]. In addition to these approaches, Chen et al [20] used a method based on premixed flamelets for the simulation of lifted methane jet flames.…”

Section: Introductionmentioning

confidence: 99%

Transported PDF simulation of auto-ignition of a turbulent methane jet in a hot, vitiated coflow

Fiolitakis

Arndt

2019

Combustion Theory and Modelling

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In the current work, the auto-ignition of a turbulent round methane jet is studied numerically by means of a transported probability density function (PDF) method. The methane jet is issued into a hot, vitiated coflow, where it ignites to form a steady lifted flame. For this flame, experimental data of hydroxyl, temperature and mixture fraction are provided in the area where the fuel auto-ignites. To model this experiment, the transport equation for the thermochemical PDF is solved using a hybrid finite volume / Lagrangian Monte-Carlo method. Turbulence is modeled using the k-ε turbulence model including a jet-correction. Computational results are compared to experimental data in terms of mean quantities, variances and liftoff height. Moreover, the structure of the one-point, one-time marginal PDF of temperature is analyzed and compared to experimental data which are provided in this work. It is found that the transported PDF method in conjunction with the k-ε model is capable of reproducing these statistical data very well. In particular the effect of ignition on the marginal PDF of temperature can be well reproduced with this approach. To further analyze the relevant processes in the evolution of the temperature PDF, a statistically homogeneous system is studied both numerically and analytically.

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LES of Delft Jet-in-Hot Coflow burner to investigate the effect of preferential diffusion on autoignition of CH4/H2 flames

Cited by 27 publications

References 39 publications

Impact of sub-grid scale models on resolving mixing and thermal shear layers in large eddy simulation of JHC flames

Impact of sub-grid scale models on resolving mixing and thermal shear layers in large eddy simulation of JHC flames

Effects of infinitely fast chemistry on combustion behavior of coaxial diffusion flame predicted by large eddy simulation

Transported PDF simulation of auto-ignition of a turbulent methane jet in a hot, vitiated coflow

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