Multiscale analysis of turbulence-flame interaction in premixed flames

Doan, Nguyen Anh Khoa; Swaminathan, Nedunchezhian; Chakraborty, Nilanjan

doi:10.1016/j.proci.2016.07.111

Cited by 29 publications

(50 citation statements)

References 31 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…These results are consistent with the earlier findings of Doan et al 14 . The current analysis focuses on the behaviour of the aforementioned alignment for wall-bounded premixed flames.…”

Section: A Influence Of Combustion On Vortex Stretchingsupporting

confidence: 94%

“…The bandpass filtering method used here suppresses eddies smaller or larger than L, and thus the flame stretch induced by eddies of size L can be extracted. The filtering technique developed in 35 has been successfully used to investigate freely-propagating statistically planar flames 14 . In the present work, the aforementioned technique is slightly modified to analyse wall-bounded flows.…”

Section: Bandpass Filteringmentioning

confidence: 99%

“…Premixed combustion typically occurs at the small scales in the spectrum of turbulence ranging from large energy containing (integral) scales to small viscous (Kolmogorov) scales. However, this whole spectrum of scales does not play a significant role on the flame 14,36 , as the Kolmogorov scales are too weak to stretch the flame 38 . The focus here is on how the small scales of turbulence affect premixed flames in wall-bounded flows.…”

Section: Introductionmentioning

confidence: 99%

“…The behaviour of flame stretch is dependent on how the strain rate behaves under the influence of heat release. Hence it is important to understand the dynamics of the underlying strain field and this has been investigated for freely-propagating statistically planar flames in past studies 14 . The presence of walls alters the turbulence and strain rate structure considerably and thus it is worthwhile to investigate the contributions of small scale eddies to the overall stretch and also its implications on the Large Eddy Simulation (LES) modelling of flame-wall interaction (FWI).…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Multiscale analysis of head-on quenching premixed turbulent flames

et al. 2018

Self Cite

View full text Add to dashboard Cite

Multiscale analysis of wall-bounded turbulent premixed flames is performed using three-dimensional direct numerical simulation (DNS) data of flame-wall interaction (FWI). The chosen configuration represents head-on quenching of a turbulent statistically planar stoichiometric methane-air flame by an isothermal inert wall. Different turbulence intensities and chemical mechanism have been analysed. A bandpass filtering technique is utilised to analyse the influence of turbulent eddies of varying size and the statistics of vorticity and strain rate fields associated with them. It is found that the presence of the flame does not alter the mechanism of vortex stretching in turbulent flows when the flame is away from the wall, but in the case of FWI, the mechanism of vortex stretching is altered due to a reduction in the contribution from non-local strain, and the small scales of turbulence start to contribute to flame straining process. The results indicate that small scale eddies do not contribute to the tangential strain rate when the flames are away from the walls, whereas the contribution from the small scales to the tangential strain rate increases when the flame is in the vicinity of the wall. It is also found that the choice of chemical mechanism does not influence the underlying fluid mechanical processes involved in flame-wall interaction.

show abstract

“…These results are consistent with the earlier findings of Doan et al 14 . The current analysis focuses on the behaviour of the aforementioned alignment for wall-bounded premixed flames.…”

Section: A Influence Of Combustion On Vortex Stretchingsupporting

confidence: 94%

Section: Bandpass Filteringmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Multiscale analysis of head-on quenching premixed turbulent flames

et al. 2018

Self Cite

View full text Add to dashboard Cite

show abstract

“…The effect of strain on a premixed flamelet is well accepted to be important in the case of RANS simulations, however its relevance for LES is more controversial. Recent findings [20,21] show that, since part of the strain is resolved in the LES, its effect on the flame is implicitly captured as long as the local mesh size is appropriate. These preliminary findings have been confirmed by GT calculations [22][23][24] and show that strained flamelets are unnecessary at least for the conditions considered.…”

Section: Introductionmentioning

confidence: 99%

The Role of CFD in Modern Jet Engine Combustor Design

Chen¹,

Langella²,

Swaminathan³

2020

Environmental Impact of Aviation and Sustainable Solutions

View full text Add to dashboard Cite

Recent advances in the application of computational fluid dynamics (CFD) for turbulent combustion with the relevance for gas turbine jet engines are discussed. Large eddy simulation (LES) has emerged as a powerful approach to handle the highly turbulent, unsteady and thermochemically non-linear flows in the practical combustors, and it is a matter of time for the industry to replace the conventional Reynolds averaged Navier-Stokes (RANS) approach by LES as the main CFD tool for combustor research and development. Since combustion is a subgrid scale phenomenon in LES, appropriate modelling is required to describe the SGS combustion effects on the resolved scales. Among the various available models, the flamelet approach is seen to be a promising candidate for practical application because of its computational efficiency, robustness and accuracy. A revised flamelet formulation, FlaRe, is introduced to outline the general LES methodology for combustion modelling and then used for a range of test cases to demonstrate its capabilities for both laboratory burners and practical engine combustors. The LES results generally compare well with the experimental measurements showing that the important physical processes are captured in the simulations.

show abstract

Filtered Reaction Rate Modelling in Moderate and High Karlovitz Number Flames: an a Priori Analysis

Nilsson

Doan

et al. 2019

Flow Turbulence Combust

View full text Add to dashboard Cite

Direct numerical simulations (DNS) of statistically planar flames at moderate and high Karlovitz number (Ka) have been used to perform an a priori evaluation of a presumed-PDF model approach for filtered reaction rate in the framework of large eddy simulation (LES) for different LES filter sizes. The model is statistical and uses a presumed shape, based here on a beta-distribution, for the sub-grid probability density function (PDF) of a reaction progress variable. Flamelet tabulation is used for the unfiltered reaction rate. It is known that presumed PDF with flamelet tabulation may lead to over-prediction of the modelled reaction rate. This is assessed in a methodical way using DNS of varying complexity, including single-step chemistry and complex methane/air chemistry at equivalence ratio 0.6. It is shown that the error is strongly related to the filter size. A correction function is proposed in this work which can reduce the error on the reaction rate modelling at low turbulence intensities by up to 50%, and which is obtained by imposing that the consumption speed based on the modelled reaction rate matches the exact one in the flamelet limit. A second analysis is also conducted to assess the accuracy of the flamelet assumption itself. This analysis is conducted for a wide range of Ka, from 6 to 4100. It is found that at high Ka this assumption is weaker as expected, however results improve with larger filter sizes due to the reduction of the scatter produced by the fluctuations of the exact reaction rate.

show abstract

Multiscale analysis of turbulence-flame interaction in premixed flames

Cited by 29 publications

References 31 publications

Multiscale analysis of head-on quenching premixed turbulent flames

Multiscale analysis of head-on quenching premixed turbulent flames

The Role of CFD in Modern Jet Engine Combustor Design

Filtered Reaction Rate Modelling in Moderate and High Karlovitz Number Flames: an a Priori Analysis

Contact Info

Product

Resources

About