Modelling of soot formation in a heavy-duty diesel engine with conditional moment closure

Bolla, Michele; Farrace, Daniele; Wright, Yuri M.; Boulouchos, Konstantinos

doi:10.1016/j.fuel.2013.09.041

Cited by 38 publications

(16 citation statements)

References 46 publications

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“…Since LES-FRC simulations are computationally very expensive, especially at the high Reynolds numbers encountered in real-scale combustion devices (Gicquel et al, 2012), they decided to perform unsteady Reynolds averaged Navier-Stokes simulations (URANS). The applicability of URANS for such applications was demonstrated earlier by Bolla et al (2014) who performed CFD soot simulations in a heavy-duty diesel engine.…”

Section: Introductionmentioning

confidence: 90%

“…The influence of soot subfilter dynamics on the resolved statistics of soot evolution was not quantified, however. Other examples where subfilter TCI models for gaseous combustion were extended to describe the subfilter dynamics of the solid phase are the linear eddy model (LEM) (El-Asrag and Menon, 2009) and conditional moment closure (CMC) (Bolla et al, 2014;Kronenburg et al, 2000).…”

Section: Governing Equationsmentioning

confidence: 99%

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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: Introductionmentioning

confidence: 90%

Section: Governing Equationsmentioning

confidence: 99%

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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“…In simple nucleation models, nucleation rates are correlated to the acetylene concentration [7]. Because such models are computationally efficient, they are nowadays often used for simulations of complex combustion configurations as for example turbulent jet flames [8,9], gas turbine combustors [10] or diesel engines [11]. A recent study by Roy and Haworth [12] confirmed that good soot predictions can be obtained with such models.…”

Section: Introductionmentioning

confidence: 99%

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

Eberle

Gerlinger

Aigner

2017

Combustion and Flame

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“…Magnussen's eddy dissipation) [11,12]. With the development of the flamelet model in the 1990s, more advanced turbulent combustion theories started to appear in the field of diesel engine computational fluid dynamics (CFD) [13][14][15], and more recently, all advanced combustion models are being used: CMC [16][17][18][19][20][21], PDF [22][23][24][25], partially stirred reactor [26], generalised flame surface density model [27], FPV models [28] and the flamelet generated manifold method [29].…”

Section: Introductionmentioning

confidence: 99%

“…Further to the investigations reported in [22][23][24] using the composition PDF approach, this study employs a well-proven CMC combustion model [16][17][18][19][20][21]36] in conjunction with an embedded soot model [37] to study the impact of neglecting TCI with particular emphasis on emissions. The present investigation additionally seeks to elucidate the reasons behind the apparent success of neglecting TCI by examining the predicted ignition delays, LOLs and soot distributions for a variety of diesel engine relevant conditions.…”

Section: Introductionmentioning

confidence: 99%

Influence of turbulence–chemistry interaction forn-heptane spray combustion under diesel engine conditions with emphasis on soot formation and oxidation

Bolla

Farrace

Wright

et al. 2014

Combustion Theory and Modelling

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The influence of the turbulence-chemistry interaction (TCI) for n-heptane sprays under diesel engine conditions has been investigated by means of computational fluid dynamics (CFD) simulations. The conditional moment closure approach, which has been previously validated thoroughly for such flows, and the homogeneous reactor (i.e. no turbulent combustion model) approach have been compared, in view of the recent resurgence of the latter approaches for diesel engine CFD. Experimental data available from a constant-volume combustion chamber have been used for model validation purposes for a broad range of conditions including variations in ambient oxygen (8-21% by vol.), ambient temperature (900 and 1000 K) and ambient density (14.8 and 30 kg/m 3 ). The results from both numerical approaches have been compared to the experimental values of ignition delay (ID), flame lift-off length (LOL), and soot volume fraction distributions. TCI was found to have a weak influence on ignition delay for the conditions simulated, attributed to the low values of the scalar dissipation relative to the critical value above which auto-ignition does not occur. In contrast, the flame LOL was considerably affected, in particular at low oxygen concentrations. Quasi-steady soot formation was similar; however, pronounced differences in soot oxidation behaviour are reported. The differences were further emphasised for a case with short injection duration: in such conditions, TCI was found to play a major role concerning the soot oxidation behaviour because of the importance of soot-oxidiser structure in mixture fraction space. Neglecting TCI leads to a strong over-estimation of soot oxidation after the end of injection. The results suggest that for some engines, and for some phenomena, the neglect of turbulent fluctuations may lead to predictions of acceptable engineering accuracy, but that a proper turbulent combustion model is needed for more reliable results.

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Modelling of soot formation in a heavy-duty diesel engine with conditional moment closure

Cited by 38 publications

References 46 publications

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

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

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

Influence of turbulence–chemistry interaction forn-heptane spray combustion under diesel engine conditions with emphasis on soot formation and oxidation

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