A sectional PAH model with reversible PAH chemistry for CFD soot simulations

Eberle, Christian; Gerlinger, Peter; Aigner, Manfred

doi:10.1016/j.combustflame.2017.01.019

Cited by 39 publications

(66 citation statements)

References 67 publications

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“…10 yields a total soot growth term of 0.01 kg/(m 3 s) with the contributions of nucleation, PAH-condensation, and C 2 H 2addition being 8.6 %, 9.4 % and 82.0 %. In comparison to the literature (Eberle et al, 2017;Xu et al, 1997;Kazakov et al, 1995;Balthasar and Frenklach, 2005;Eaves et al, 2012), the contribution of nucleation to total soot growth is very high which possibly indicates significant errors from the simplified treatment of PAH chemistry. Thus, future studies of this burner should use a more accurate PAH chemistry.…”

Section: Soot Evolutionmentioning

confidence: 59%

“…Firstly, the maximum soot volume fraction in the LES (f v,max = 0.64 ppm) and the URANS (f v,max = 0.47 ppm) is significantly higher than in the experiment (f v,max = 0.037 ppm). A possible reason for this deviation is the irreversible description of PAH chemistry which has been shown to cause a too strong soot nucleation rate possibly leading to an overprediction of f v (Eberle et al, 2017). In this study, Eberle et al…”

Section: Soot Evolutionmentioning

confidence: 71%

See 1 more Smart Citation

Toward finite-rate chemistry large-eddy simulations of sooting swirl flames

Eberle

Gerlinger

Geigle

et al. 2018

Combustion Science and Technology

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This paper presents time-resolved numerical simulations of a well-characterized sooting swirl flame at elevated pressure. Recently published unsteady Reynolds averaged Navier-Stokes simulations (URANS) are compared here to newly performed large eddy simulations (LES). Finite-rate chemistry, where transport equations are solved for each chemical species, is employed for the gas phase, a sectional approach for polycyclic aromatic hydrocarbons (PAHs), and a two-equation model for soot particles. Feedback effects such as the consumption of gaseous soot precursors by growth of soot and PAHs are inherently captured accurately by a coupled solution of the set of governing equations. The numerical results (velocity components, temperature and soot volume fraction) compare well with experimental data. No significant differences between URANS and LES are observed for timeaveraged temperatures and velocity components, while the prediction of soot is significantly improved by LES. It will be shown that an accurate description of the instantaneous flame structure (especially of the hydroxyl radical distribution) by resolution of turbulent scales is of fundamental importance for accurate soot predictions in confined swirl flames with strong secondary air injection.

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Section: Soot Evolutionmentioning

confidence: 59%

Section: Soot Evolutionmentioning

confidence: 71%

Toward finite-rate chemistry large-eddy simulations of sooting swirl flames

Eberle

Gerlinger

Geigle

et al. 2018

Combustion Science and Technology

View full text Add to dashboard Cite

show abstract

“…Following the current understanding, PAHs play an important role in soot inception and growth and hence sectional models based on PAHs have been developed (e.g. [138,139]). Such models require complex chemistry (many species and reactions involved, even for simple hydrocarbons [140]) increasing the computational cost of approaches based on the online solution of the chemistry.…”

Section: Examplesmentioning

confidence: 99%

Turbulent Combustion Modelling and Experiments: Recent Trends and Developments

Giusti

Mastorakos

2019

Flow Turbulence Combust

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The development of better laser-based experimental methods and the fast rise in computer power has created an unprecedented shift in turbulent combustion research. The range of species and quantities measured and the advent of kHz-level planar diagnostics are now providing great insights in important phenomena and applications such as local and global extinction, pollutants, and spray combustion that were hitherto unavailable. In simulations, the shift to LES allows better representation of the turbulent flow in complex geometries, but despite the fact that the grid size is smaller than in RANS, the push towards realistic conditions and the need to include more detailed chemistry that includes very fast species and thin reaction zones emphasize the necessity of a sub-grid turbulent combustion model. The paper discusses examples from current research with experiments and modelling that focus on flame transients (self-excited oscillations, local extinction), sprays, soot emissions, and on practical applications. These demonstrate how current models are being validated by experimental data and the concerted efforts the community is taking to promote the modelling tools to industry. In addition, the various coordinated International Workshops on non-premixed, premixed, and spray flames, and on soot are discussed and some of their target flames are explored. These comprise flames that are relatively simple to describe from a fluid mechanics perspective but contain difficult-to-model combustion problems such as extinction, pollutants and multi-mode reaction zones. Recently, swirl spray flames, which are more representative of industrial devices, have been added to the target flames. Typically, good agreement is found with LES and some combustion models such as the progress variable-mixture fraction flamelet model, the Conditional Moment Closure, and the Transported PDF method, but predicting soot emissions and the condition of complete extinction in complex geometries is still elusive.

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“…[31][32][33] This model has more recently found application in the CFD field. 28,29,[34][35][36] Computationally less expensive than very detailed soot modeling, 37,38 the sectional approach provides a good accuracy. Di Domenico 34 used for the first time the sectional approach for the CFD simulation of soot formation in gas turbine combustors.…”

Section: Char Description With Discrete Classesmentioning

confidence: 99%

A Sectional Approach for the Entrained-Flow Gasification of Slurry Fuels

2018

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Energy densification is the overall objective of the on-going bioliq project. Bioslurry, obtained via fast pyrolysis of low-grade biogenic resources, is converted into high quality syngas in a high pressure entrained flow gasifier. The modeling of this three-phase system involving high pressure and high temperature sub-processes is very challenging. The detailed representation of the chemical sub-processes goes along with an increase of the computational cost. In this work, a novel approach is developed to achieve fast and accurate Computational Fluid Dynamics (CFD) simulations of the gasification of a slurry fuel in a laboratory entrained flow gasifier under atmospheric pressure. The method investigated relies on a sectional approach to describe the char gasification. An Euler-Euler approach is used for the modeling of the slurry/gas phase system. Ethylene glycol is used to represent the liquid part of the slurry. Experimental

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A sectional PAH model with reversible PAH chemistry for CFD soot simulations

Cited by 39 publications

References 67 publications

Toward finite-rate chemistry large-eddy simulations of sooting swirl flames

Toward finite-rate chemistry large-eddy simulations of sooting swirl flames

Turbulent Combustion Modelling and Experiments: Recent Trends and Developments

A Sectional Approach for the Entrained-Flow Gasification of Slurry Fuels

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