Computations of turbulent lean premixed combustion using conditional moment closure

Amzin, Shokri; Swaminathan, Nedunchezhian

doi:10.1080/13647830.2013.848382

Cited by 21 publications

(18 citation statements)

References 46 publications

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“…Another method known as the Conditional Moment Closure (CMC) [3] also exists. Recently this method has enjoyed some success for modelling premixed flames [4,5], but more work is needed to make this approach robust for premixed combustion. One of the major problems associated with the CMC approach is the modelling of conditional scalar dissipation rate in premixed flames [6].…”

Section: Introductionmentioning

confidence: 99%

Modelling flame turbulence interaction in RANS simulation of premixed turbulent combustion

Ahmed

Prosser

2015

Combustion Theory and Modelling

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Flame turbulence interaction ( ∆ c ) is an important term for modelling scalar dissipation ( ε c ) in premixed turbulent combustion. In order to obtain an accurate representation of the flame turbulence interaction phenomenon, an evolution equation for ∆ c has recently been proposed. This equation gives a detailed insight into the flame turbulence interaction phenomenon and provides an alternative approach to model the important physics represented by ∆ c . In this paper the ∆ c evolution equation is used to model a premixed propane-air flame stabilised in a turbulent mixing layer. The simulations are carried out in the context of a Reynolds Averaged Navier Stokes (RANS) framework and the results are compared with the experiments and also with the Large Eddy Simulation (LES). It is found that the modelling strategy involving the ∆ c evolution equation gives good approximations for the mean velocities and flame locations in the mixing layer stabilised flame when compared with other modelling strategies.

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Section: Introductionmentioning

confidence: 99%

Modelling flame turbulence interaction in RANS simulation of premixed turbulent combustion

Ahmed

Prosser

2015

Combustion Theory and Modelling

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“…The termcð1 ÀcÞ=β c comes from combined influences of flame front curvature effects induced by turbulence, chemical reaction, and molecular dissipation processes Chakraborty and Swaminathan, 2007). Although a reasonably robust value of β c ¼ 6:7 was established in past RANS calculations of various premixed flames (Ahmed and Swaminathan, 2013;Amzin and Swaminathan, 2013;Amzin et al, 2012;Kolla et al, 2009;Ruan et al, 2014;Swaminathan et al, 2012), this value cannot be used for LES because the processes influencing β c are effected by SGS turbulence. Thus, it can be evaluated dynamically as suggested by Langella et al (2015) and Gao et al (2014).…”

Section: Algebraic Closure For Filtered Reaction Ratementioning

confidence: 99%

“…The nonflamelets category includes transported PDF and conditional moment closure (CMC) methodologies. The CMC method (Klimenko and Bilger, 1999) was tested rigorously for RANS simulations of premixed flames (Amzin and Swaminathan, 2013;Amzin et al, 2012;Martin et al, 2003) but yet to be applied for LES of premixed combustion. Different PDF approaches have been used for LES of premixed combustion (Bulat et al, 2014;Dodoulas and NavarroMartinez, 2013;Rowinski and Pope, 2013).…”

Section: Introductionmentioning

confidence: 99%

Large Eddy Simulation of Premixed Combustion: Sensitivity to Subgrid Scale Velocity Modeling

Langella

Swaminathan

Gao

et al. 2016

Combustion Science and Technology

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An algebraic reaction rate closure involving filtered scalar dissipation rate of reaction progress variable is studied. The filtered scalar dissipation rate closure requires a model for sub-grid scale velocity, u 0 Δ , which is estimated using four algebraic models and transported subgrid scale kinetic energy. A priori analyses using direct numerical simulation (DNS) data show that the filtered dissipation rate, and thus the reaction rate closure, has some sensitivity to the u 0 Δ model. The sensitivity of various statistics obtained from large eddy simulation (LES) of three piloted Bunsen flames of stoichiometric methaneair mixture to the modeling of u 0 Δ is observed to be weaker compared to that for the DNS analysis. Moreover, analysis using transported sub-grid scale kinetic energy does not indicate a necessity to include flame-generated turbulence in the modeling of u 0 Δ for the Bunsen flames in the thin reaction zones regime. The measured and computed flame brush structures are compared and studied and the algebraic closure for the filtered reaction rate is found to be quite good. ARTICLE HISTORY

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“…The non-flamelet methodology includes the transported PDF and the conditional moment closure (CMC) approaches. The CMC method [22] was tested rigorously for RANS simulations of premixed flames [23][24][25] but has yet to be applied in the LES framework. Different PDF approaches have been used for LES of premixed combustion, and details can be found elsewhere [26][27][28][29].…”

Section: Introductionmentioning

confidence: 99%

Unstrained and strained flamelets for LES of premixed combustion

Langella

Swaminathan

2016

Combustion Theory and Modelling

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The unstrained and strained flamelet closures for filtered reaction rate in large eddy simulation (LES) of premixed flames are studied. The required sub-grid scale (SGS) PDF in these closures is presumed using the Beta function. The relative performances of these closures are assessed by comparing numerical results from large eddy simulations of piloted Bunsen flames of stoichiometric methane-air mixture with experimental measurements. The strained flamelets closure is observed to underestimate the burn rate and thus the reactive scalars mass fractions are under-predicted with an overprediction of fuel mass fraction compared with the unstrained flamelet closure. The physical reasons for this relative behaviour are discussed. The results of unstrained flamelet closure compare well with experimental data. The SGS variance of the progress variable required for the presumed PDF is obtained by solving its transport equation. An order of magnitude analysis of this equation suggests that the commonly used algebraic model obtained by balancing source and sink in this transport equation does not hold. This algebraic model is shown to underestimate the SGS variance substantially and the implications of this variance model for the filtered reaction rate closures are highlighted. Nomenclature AcronymsCDF cumulative distribution function CFL Courant-Friedrichs-Lewy number LES large eddy simulation PDF probability density function RANS Reynolds averaged Navier-Stokes SF strained flamelets SGS sub-grid scale TKE turbulent kinetic energy UF unstrained flamelet Roman c progress variable C p specific heat capacity at constant pressure (kJ kg -1 K -1 ) C 3 , C 4 parameters in Equation (7) D molecular diffusivity (m 2 s −1 )

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Computations of turbulent lean premixed combustion using conditional moment closure

Cited by 21 publications

References 46 publications

Modelling flame turbulence interaction in RANS simulation of premixed turbulent combustion

Modelling flame turbulence interaction in RANS simulation of premixed turbulent combustion

Large Eddy Simulation of Premixed Combustion: Sensitivity to Subgrid Scale Velocity Modeling

Unstrained and strained flamelets for LES of premixed combustion

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