Recent developments in DNS of turbulent combustion

Domingo, Pascale

doi:10.1016/j.proci.2022.06.030

Cited by 23 publications

(4 citation statements)

References 270 publications

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“…Combustion CFD simulations proceeded through the development of different techniques depending on the spatial/temporal scale to be investigated (especially where turbulence/mixing plays a dominant role in the combustion process) and depending if any additional transport/chemistry mechanisms must be introduced: DNS should be in principle the most complete approach [2] but the computation effort in terms of CPU time could be excessively expensive such that RANS and LES approaches are preferred in some case to simulate specific flames' behaviours.…”

Section: Introductionmentioning

confidence: 99%

Hydrogen Combustion for an Industrial Gas Turbine Burner: OH* Chemiluminescence Preliminary Measurements

Romano,

Miris,

Gallo

et al. 2024

Proceedings of the 9th World Congress on Momentum, Heat and Mass Transfer

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In order to meet future decarbonization objectives and limit the negative effect on climate change looking at the energy production sector, gas turbine combustion plays a key role to get the "most" and the "best" energy from smart and clean fuels. Gas turbine combustors typically designed and operated with traditional fuels like natural gas and diesel oils, could meet several challenges when facing carbon-free fuels like hydrogen or ammonia; the high reactivity of hydrogen could lead to flashback issues in premixed flames and the nitrogen-bound nature of ammonia could lead to unacceptable levels of exhaust NOx emissions. Understanding the behaviour of an existing combustion system when fuel nature is radically modified, is fundamental since it allows to identify the effort level for a potential design modification of the baseline or to conclude that a jump to a different combustion technology is necessary. In this paper an innovative industrial gas turbine burner has been characterized in atmospheric conditions in terms of NOx exhaust emissions together with a qualitative structure of the flame through OH* chemiluminescence imaging with pure hydrogen or hydrogen/methane mixtures as fuel. The present information represents also a good starting point in validating Computational Fluid Dynamics (CFD) codes, especially when non-conventional fuels are involved.

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Section: Introductionmentioning

confidence: 99%

Hydrogen Combustion for an Industrial Gas Turbine Burner: OH* Chemiluminescence Preliminary Measurements

Romano,

Miris,

Gallo

et al. 2024

Proceedings of the 9th World Congress on Momentum, Heat and Mass Transfer

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“…Moreover, stratified-mixture combustion can also take place as a result of unintentional inadequate mixing. Lipatnikov [14] and Domingo et al [15] provided an extensive review of experimental and numerical findings of stratified-mixture combustion. High-performance computing has enabled DNS of stratified-mixture combustion [1][2][3][4][5][6][7][8][9][10][11][12][13][16][17][18][19], and the vast majority of these studies have been conducted for statistically planar flames in canonical 'flame-in-a-box' configuration [1][2][3][4][5][6][7][8][9][10][11][12][13].…”

Section: Introductionmentioning

confidence: 99%

Implications of Using Scalar Forcing to Sustain Reactant Mixture Stratification in Direct Numerical Simulations of Turbulent Combustion

Brearley,

Ahmed,

Chakraborty

2024

Computation

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A recently proposed scalar forcing scheme that maintains the mixture fraction mean, root-mean-square and probability density function in the unburned gas can lead to a statistically quasi-stationary state in direct numerical simulations of turbulent stratified combustion when combined with velocity forcing. Scalar forcing alongside turbulence forcing leads to greater values of turbulent burning velocity and flame surface area in comparison to unforced simulations for globally fuel-lean mixtures. The sustained unburned gas mixture inhomogeneity changes the percentage shares of back- and front-supported flame elements in comparison to unforced simulations, and this effect is particularly apparent for high turbulence intensities. Scalar forcing does not significantly affect the heat release rates due to different modes of combustion and the micro-mixing rate within the flame characterised by scalar dissipation rate of the reaction progress variable. Thus, scalar forcing has a significant potential for enabling detailed parametric studies as well as providing well-converged time-averaged statistics for stratified-mixture combustion using Direct Numerical Simulations in canonical configurations.

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“…Direct numerical simulation (DNS) plays a crucial rule in understanding the fundamental turbulent combustion processes because of its capability to not only fully resolve the turbulent flow field but also verify the validity of various models 10 . Unlike the premixed flamevortex interaction, which has been extensively studied in homogeneous isotropic turbulence, mixing shearing layer or jet configurations 11 , diffusion or non-premixed flames have received much less attention and the underlying physics of their interaction with vortex requires further investigation.…”

Section: Introductionmentioning

confidence: 99%

“…Then the effects of molecular diffusion modelling (including mixtureaveraged diffusion and unity Lewis number) on the flame structure 22 will be investigated as the differential diffusion plays a significant role role in a hydrogen-air combustion due to the high diffusivity of hydrogen and its atom radical 23 . In addition, all the DNS databases will be made publicly available, motivating the community building around database sharing 24,25 , which is essential for emerging research activities such as deep learning-assisted combustion modelling 20,26 .…”

Section: Introductionmentioning

confidence: 99%

Direct numerical simulations of the Taylor-Green Vortex interacting with a hydrogen diffusion flame: Reynolds number and non-unity Lewis number effects

Xu¹,

Chen²

2023

Preprint

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Understanding the interactions between hydrogen flame and turbulent vortices is important for developing the next-generation carbon neutral combustion systems.In the present work, we perform several direct numerical simulation (DNS) cases to study the dynamics of a hydrogen diffusion flame embedded in the Taylor-Green Vortex (TGV). The evolution of flame and vortex is investigated for a range of initial Reynolds numbers up to 3200 with different mass diffusion models. We show that the vortices dissipate rapidly in cases at low Reynolds numbers, while the consistent stretching, splitting and twisting of vortex tubes are observed in cases with evident turbulence transition at high Reynolds numbers. Regarding the interactions between the flame and vortex, it is demonstrated that the heat release generated by the flame has suppression effects on the turbulence intensity and its development of the TGV.Meanwhile, the intense turbulence provides abundant kinetic energy, accelerating the mixing of the diffusion flame with a contribution to higher strain rate and larger curvatures of the flame. Considering the effects of non-unity Lewis number, it is revealed that the flame strength is more intense in the cases with mixture averaged model. However, this effect is relatively suppressed under the impacts of the intense turbulence.

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Recent developments in DNS of turbulent combustion

Cited by 23 publications

References 270 publications

Hydrogen Combustion for an Industrial Gas Turbine Burner: OH* Chemiluminescence Preliminary Measurements

Hydrogen Combustion for an Industrial Gas Turbine Burner: OH* Chemiluminescence Preliminary Measurements

Implications of Using Scalar Forcing to Sustain Reactant Mixture Stratification in Direct Numerical Simulations of Turbulent Combustion

Direct numerical simulations of the Taylor-Green Vortex interacting with a hydrogen diffusion flame: Reynolds number and non-unity Lewis number effects

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