LES/PDF based modeling of soot–turbulence interactions in turbulent flames

Donde, Pratik; Raman, Venkat; Müeller, Michael E.; Pitsch, Heinz

doi:10.1016/j.proci.2012.07.055

Cited by 55 publications

(42 citation statements)

References 30 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…With this basis for turbulence modeling, three additional components are required for modeling soot evolution: (a) a turbulent combustion model to describe the interactions between turbulence, gas-phase chemistry, and molecular transport; (b) a chemical kinetics model that links gas-phase combustion and soot precursor evolution to soot evolution through nucleation, condensation and surface growth; and (c) a soot population balance model and solution methodology that allows nanoparticles to be represented in a computationally tractable manner. Prior studies have shown that for flames that are not close to extinction, different combustion models produce comparable results [15,16] . Therefore, the focus here will be on the latter two modeling components mentioned above.…”

Section: Article In Pressmentioning

confidence: 99%

“…The semi-empirical acetylene-based inception mechanism produces very good reproduction of soot volume fraction for smaller hydrocarbon flames [4,5,23] but vastly underpredicts inception for higher hydrocarbons such as kerosene [25] . Among the PAH-based nucleation models, those based on pyrene (A4) as soot precursor have often underpredicted the soot volume for ethylene and small-hydrocarbon flames [15,26] , while reasonable agreement was obtained for jet fuels [14] .…”

Section: Article In Pressmentioning

confidence: 99%

See 1 more Smart Citation

Effect of soot model, moment method, and chemical kinetics on soot formation in a model aircraft combustor

Chong

Raman

Müeller

et al. 2019

Proceedings of the Combustion Institute

Self Cite

View full text Add to dashboard Cite

CitationChong ST, Raman V, Mueller ME, Selvaraj P, Im HG (2018 AbstractThe simulation of turbulent sooting flames requires a host of models, of which the two critical components are the chemical kinetics that describe soot precursor evolution and the description of the soot population. The purpose of this study is to understand the sensitivity of soot predictions in a realistic aircraft combustor to model choices for these components. Two different chemistry mechanisms, three different statistical approaches, and two different soot inception models are considered. The simulations show that acetylene-based soot inception produces very high soot volume fraction, with the soot particles present predominantly in the inner recirculation zone of the swirl-stabilized combustor. The PAH-based nucleation models lead to soot generation in the shear layers emanating from fuel injection. The two advanced statistical approaches (Hybrid and Conditional Quadrature Method of Moments) also show significant differences. While the Hybrid method produces lower soot number density, it also generates larger soot particles due to a faster predicted rate of coagulation. The Conditional Quadrature approach produces much higher soot number density, but its particle sizes are smaller compared to the Hybrid method for all kinetic mechanisms considered. This experimental combustor is strongly dominated by surface growth based soot mass addition. As a result, even if nucleation/condensation rates are different, the final soot mass yield is comparable for PAH-based soot models. These results indicate the importance of not only the chemical mechanism, which may be less important in this surface growth dominated combustor, but also the soot statistical model, to which coagulation and the soot surface area are relatively sensitive.

show abstract

Section: Article In Pressmentioning

confidence: 99%

Section: Article In Pressmentioning

confidence: 99%

Effect of soot model, moment method, and chemical kinetics on soot formation in a model aircraft combustor

Chong

Raman

Müeller

et al. 2019

Proceedings of the Combustion Institute

Self Cite

View full text Add to dashboard Cite

show abstract

“…The over prediction of soot volume fraction can be directly related with the over prediction of soot nucleation at high temperatures (in the absence of radiation). The balance of production and consumption in PAH are accurately captured, resulting in accurate predictions of maximum soot volume fraction location when compared to Mueller et al [10] and Donde et al [44]. The over prediction of soot volume fraction by Muller et al [10] can be attributed to the usage of higher sub filter dissipation rate.…”

Section: Soot Predictionsmentioning

confidence: 95%

“…The over prediction of soot volume fraction can be directly related with the over estimation of surface growth. The balance of surface growth and oxidation are not accurately included, resulting in accurate predictions of maximum soot volume fraction when compared to Mueller et al [10] and Donde et al [44]. In LES study of Donde et al [44], the soot-turbulence interaction increased the net soot production.…”

Section: Soot Turbulence Interactionmentioning

confidence: 95%

Effect of precursors and radiation on soot formation in turbulent diffusion flame

Reddy

Yadav³

2015

Fuel

View full text Add to dashboard Cite

a b s t r a c tSoot formation in 'Delft Flame III', a pilot stabilized turbulent diffusion flame burning natural gas/air, is investigated using ANSYS FLUENT by considering two different approaches for soot inception. In the first approach soot inception is based on the formation rate of acetylene, while the second approach considers the formation rate of two and three-ringed aromatics to describe the soot inception (Hall et al., 1997). Transport equations are solved for soot mass fraction and radical nuclei concentration to describe inception, coagulation, surface growth, and oxidation processes. The turbulent-chemistry interactions and soot precursors are described by the steady laminar flamelet model (SLFM). Two chemical mechanisms GRI 3.0 (Gregory et al.) and POLIMI (Ranzi et al., 2012) are used to represent the effect of species concentration on soot formation. The radiative properties of the medium are included based on the nongray modeling approach by considering four factious gases; the weighted sum of gray gas (WSGGM) approach is used to model the absorption coefficient. The effect of soot on radiative transfer is modeled in terms of effective absorption coefficient of the medium. A beta probability density function (b-PDF) in terms of normalized temperature is used to describe the effect of turbulence on soot formation. The results clearly elucidate the strong effect of radiation and species concentration on soot volume fraction predictions. Due to increase in radiative heat loss with soot, flame temperature decreases slightly. The inclusion of ethylene has less synergic effect than that of both benzene and ethylene. Both cases have less impact on the nucleation of soot. The increase in soot volume fraction with soot-turbulence interaction is in consistence with the DNS predictions.

show abstract

“…This is certainly the case when finite-rate chemistry is relevant, which can be expected for the relatively low temperatures encountered in fires and more precisely for toxicity calculations (such as CO). An example of state-of-the-art LES/PDF calculations, involving soot, is found in [18], while a recent review on the progress in PDF methods is found in [19].…”

Section: Theory and Model Developmentmentioning

confidence: 99%

Computer Modeling for Fire and Smoke Dynamics in Enclosures: A Help or a Burden?

Merci¹

2014

Fire Saf. Sci.

View full text Add to dashboard Cite

Fire simulations are of unique value in different respects: for fire safety system design calculations, for improving our understanding (theory and model development and validation) and for fire forecasting. In this paper the effective use of computing power for the further development of fire safety science is discussed, considering only gas phase phenomena in fire and smoke dynamics in enclosures. Arguably, much effort needs to be devoted to multi-phase phenomena (pyrolysis modeling, the effect of water or other suppressants, etc.), but this is not discussed in the paper at hand.A common feature to all types of simulations is that the Required Computing Resources (RCR), determined by the envisaged accuracy and the complexity of the problem to be tackled, must be less than the Available Computing Resources (ACR). Accuracy, reliability and dimensionality of the models used, must therefore be related to the problem tackled. In order to make progress, bench-marking studies, as a joint effort made by modelers and experimentalists, with transparent communication, are argued to be a good approach for systematic progress in the development of, and confidence in, models.Using Computational Fluid Dynamics (CFD) can be very valuable for the development of theory and the study of detailed fluid mechanics phenomena, but several aspects are important to guarantee the quality of the results. Some ideas will be formulated on how to investigate requirements on the computational mesh. Turbulence -chemistry interaction (TCI) and turbulence -radiation interaction (TRI) are also discussed briefly. Yet, it is argued that a major source of uncertainty in computer simulations stems from (and will continue to stem from) the characterization of the ever changing and developing materials (i.e. the fuel), as well as from geometry dependent features (including ventilation and heat transfer). This affects the combustion and soot formation, and therefore the fire and smoke dynamics. Therefore, a user-defined fire will remain indispensible in the foreseeable future when using computer modeling for the sake of design of fire safety systems. Once this fire has been defined, CFD is best suited in regions where detail is required or complex flow patterns establish, while other forms of modeling can be considered in other regions.For real-time and forecasting applications, it is argued that sensor-assisted numerical simulations are very promising and their use is expected to become widespread in the coming decades. With increasing computing power, the use of CFD will become more feasible in this context, but for the time being zone model calculations (perhaps combined with CFD in regions where more detail is required) seem better suited to that purpose.

show abstract

LES/PDF based modeling of soot–turbulence interactions in turbulent flames

Cited by 55 publications

References 30 publications

Effect of soot model, moment method, and chemical kinetics on soot formation in a model aircraft combustor

Effect of soot model, moment method, and chemical kinetics on soot formation in a model aircraft combustor

Effect of precursors and radiation on soot formation in turbulent diffusion flame

Computer Modeling for Fire and Smoke Dynamics in Enclosures: A Help or a Burden?

Contact Info

Product

Resources

About