A dynamic SGS combustion model based on fractal characteristics of turbulent premixed flames

Yoshikawa, Itaru; Shim, Youngsam; Nada, Yuzuru; Tanahashi, Mamoru; Miyauchi, Toshio

doi:10.1016/j.proci.2012.06.166

Cited by 10 publications

(16 citation statements)

References 24 publications

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“…Also, it has an average value of 0.5 inside the reaction zone. This is completely in agreement with the currently published literatures for these types of dynamic combustion models [22,52]. This indicates a fractal dimension close to a value of 2.5.…”

Section: Modelling Engine Combustionsupporting

confidence: 92%

Large Eddy Simulation of Premixed Combustion in Spark Ignited Engines Using a Dynamic Flame Surface Density Model

Ranasinghe

Malalasekera

Clarke

2013

SAE Int. J. Engines

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Section: Modelling Engine Combustionsupporting

confidence: 92%

Large Eddy Simulation of Premixed Combustion in Spark Ignited Engines Using a Dynamic Flame Surface Density Model

Ranasinghe

Malalasekera

Clarke

2013

SAE Int. J. Engines

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“…Accordingly, the range of Re t ≈ 100 reached in the DNS by Nishiki et al 28,36 is typical even for recent simulations. For instance, among eight papers that aimed at DNS of premixed turbulent flames and were published in the proceedings of the latest 34th Combustion Symposium, 45,[47][48][49][50][51][52][53] Re t was substantially larger than 100 only in two papers, 45,52 with the combustion chemistry being reduced to a single reaction in five papers. 47,[49][50][51]53 We may also note that the DNS data by Nishiki et al 28,36 were analyzed in several recent papers.…”

Section: Simulationsmentioning

confidence: 99%

“…Nevertheless, as far as the goals of the present study are concerned, this limitation should not be overestimated, because (i) the governing phenomena, i.e., the baroclinic torque and dilatation, are localized to flame fronts, which are much thinner than the width yz , and (ii) small-scale effects are commonly less sensitive to the size of the computational domain. On the other hand, a low ratio of yz /L allowed Nishiki et al 28,36 to reach sufficiently large ratios of L/δ L , whereas the vast majority of recent DNSs 44,45,[47][48][49][50][51][52][53] …”

Section: Simulationsmentioning

confidence: 99%

“…While the former case was selected in vast majority of recent DNS studies, 44,45,[47][48][49][50][51][52][53] the latter case addressed, in particular, by Nishiki et al 28,36 is also worth investigating. To conclude this section, let us compare the present simulations with previous DNS research [31][32][33][34] into vorticity transformation in premixed turbulent flames.…”

Section: Simulationsmentioning

confidence: 99%

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A direct numerical simulation study of vorticity transformation in weakly turbulent premixed flames

2014

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Database obtained earlier in 3D Direct Numerical Simulations (DNS) of statistically stationary, 1D, planar turbulent flames characterized by three different density ratios σ is processed in order to investigate vorticity transformation in premixed combustion under conditions of moderately weak turbulence (rms turbulent velocity and laminar flame speed are roughly equal to one another). In cases H and M characterized by σ = 7.53 and 5.0, respectively, anisotropic generation of vorticity within the flame brush is reported. In order to study physical mechanisms that control this phenomenon, various terms in vorticity and enstrophy balance equations are analyzed, with both mean terms and terms conditioned on a particular value c of the combustion progress variable being addressed. Results indicate an important role played by baroclinic torque and dilatation in transformation of average vorticity and enstrophy within both flamelets and flame brush. Besides these widely recognized physical mechanisms, two other effects are documented. First, viscous stresses redistribute enstrophy within flamelets, but play a minor role in the balance of the mean enstrophy within turbulent flame brush. Second, negative correlation u · ∇ between fluctuations in velocity u and enstrophy gradient contributes substantially to an increase in the mean within turbulent flame brush. This negative correlation is mainly controlled by the positive correlation between fluctuations in the enstrophy and dilatation and, therefore, dilatation fluctuations substantially reduce the damping effect of the mean dilatation on the vorticity and enstrophy fields. In case L characterized by σ = 2.5, these effects are weakly pronounced and is reduced mainly due to viscosity. Under conditions of the present DNS, vortex stretching plays a minor role in the balance of vorticity and enstrophy within turbulent flame brush in all three cases. C 2014 AIP Publishing LLC. [http://dx

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“…Therefore, modelling the flame surface area of turbulent premixed flames in GS is of the primary interest in the present study. One approach to obtain the turbulent flame surface area for SGS combustion models is based on fractal characteristics (Chakraborty and Klein, 2008;Charlette et al, 2002a;Chatakonda et al, 2010;Fureby, 2005;Gouldin, 1987;Gülder, 1990;Knikker et al, 2004;Yoshikawa et al, 2013). The fractal characteristics have been investigated in many studies (Cohé et al, 2007;Gülder and Smallwood, 1995;Kobayashi and Kawazoe, 2000;Mantzaras, 1992;Peters, 1986;Poinsot et al, 1990;Shim et al, 2011).…”

Section: Introductionmentioning

confidence: 99%

A Fractal Dynamic SGS Combustion Model for Large Eddy Simulation of Turbulent Premixed Flames

Hiraoka

Minamoto

Shimura

et al. 2016

Combustion Science and Technology

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Direct numerical simulation of a turbulent hydrogen-air premixed plane jet flame is performed to investigate fractal characteristics and to evaluate the fractal dynamic subgrid scale (FDSGS) combustion model. The DNS results show that the fractal dimension of flame surfaces increases with the downstream distance, and the fractal dimension computed using a 3D box-counting method reaches about 2.54 in the region where turbulence is developed by mean shear. An inner cutoff representation employed in the FDSGS combustion model could be used in large eddy simulations (LES) of complicated combustion problems. Static tests show that the procedure applied in the FDSGS combustion model adequately predicts the fractal dimension, Kolmogorov length scale, and flame surface area despite the presence of strong mean shear. Dynamic model evaluations are also carried out by conducting a series of LES using the FDSGS and other combustion models. In the dynamic tests, the mean temperature distributions and peak positions of variations of a reaction progress variable fluctuation in the transverse direction obtained from the LES with the FDSGS combustion model show good agreement with the filtered DNS fields. The present evaluation also revealed that one of the strengths in the FDSGS combustion modeling approach is that the model does not require SGS turbulent velocity fluctuation, since modeling of this quantity is straightforward for neither homogeneous turbulence nor the turbulent shear flows. ARTICLE HISTORY

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A dynamic SGS combustion model based on fractal characteristics of turbulent premixed flames

Cited by 10 publications

References 24 publications

Large Eddy Simulation of Premixed Combustion in Spark Ignited Engines Using a Dynamic Flame Surface Density Model

Large Eddy Simulation of Premixed Combustion in Spark Ignited Engines Using a Dynamic Flame Surface Density Model

A direct numerical simulation study of vorticity transformation in weakly turbulent premixed flames

A Fractal Dynamic SGS Combustion Model for Large Eddy Simulation of Turbulent Premixed Flames

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