Large eddy simulations of the Darmstadt turbulent stratified flame series

Marincola, F. Cavallo; Ma, Terence; Kempf, Andreas

doi:10.1016/j.proci.2012.08.001

“…The simulations were performed using the PsiPhi code, which has been validated extensively for gas combustion [17,18], coal combustion [9,12] and spray combustion [19]. The generalised Favre filtered governing equations were solved for mass, momentum, species mass fraction and enthalpy.…”

Section: Gas Phasementioning

confidence: 99%

Large Eddy Simulation of a 100 kWth swirling oxy-coal furnace

Franchetti

¹

,

Marincola

²

,

Navarro‐Martinez

³

et al. 2016

Fuel

Self Cite

View full text Add to dashboard Cite

Large Eddy Simulation (LES) has been applied to the swirling 100 kW th OXYCOAL-AC test facility of Aachen University. A set of models to represent devolatilisation, volatile combustion, char combustion and radiation for oxy-coal combustion in an LES framework has been implemented and tested. A qualitative analysis of the flow behaviour and the overall coal combustion processes occurring within the furnace was made. The LES results for the flow field were compared to axial and tangential mean velocity measurements, showing good agreement, particularly in the upstream regions of the flame. The LES results were also compared to oxygen concentrations and gas temperature. Overall good agreement was observed in the upstream central regions of the flame, whilst downstream the LES overestimated the combustion rates. The results show the potential of using LES for more complex oxy-coal combustion burners and opens the way for applications to industrial furnaces.

show abstract

“…back-supported or front-supported flame propagation) which may not be negligible for stratified flames (e.g. Marincola et al, 2013;Inanc et al, 2020). Moreover, scalar dissipation rates N = D∇ ⋅ ∇ , N c = D∇c ⋅ ∇c and cross-scalar dissipation rate .…”

Section: Mathematical Backgroundmentioning

confidence: 99%

“…Presumed probability density function (PPDF) (Libby and Williams, 2000;Ribert et al, 2005;Robin et al, 2006), flamelet based tabulated chemistry (Darbyshire et al, 2010) and Flamelet Generated Manifold (Nguyen et al, 2010;Fiorina et al, 2015;Marincola et al, 2013) based modelling approaches require solving the transport equations of the Favre averaged active and passive scalar variances, as well as their covariance, which in turn need closures of their respective dissipation rates. Several previous analyses (Mura et al, 2007;Chakraborty, 2010a, 2011a;Chakraborty et al, 2011) focussed on modelling the scalar dissipation rates of mixture fraction and reaction progress variable in turbulent stratified mixture combustion, but relatively limited effort has been directed to the closure of cross-scalar dissipation rate.…”

Section: Introductionmentioning

confidence: 99%

“…Following this, Malkeson and Chakraborty (2011b) derived the exact transport equation of ̃ Y and proposed closures for the unclosed terms based on a-priori DNS analysis. Flame Generated Manifold (Nguyen et al, 2010;Marincola et al, 2013;Fiorina et al, 2015) closures of stratified mixture combustion utilise reaction progress variable c rather than Y F as the…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

A Priori Direct Numerical Simulation Analysis of the Closure of Cross-Scalar Dissipation Rate of Reaction Progress Variable and Mixture Fraction in Turbulent Stratified Flames

Brearley

¹

,

Ahmed

²

,

Chakraborty

³

2022

Flow Turbulence Combust

1

0

View full text Add to dashboard Cite

The cross-scalar dissipation rate of reaction progress variable and mixture fraction $$\widetilde{{\varepsilon_{c\xi } }}$$ ε c ξ ~ plays an important role in the modelling of stratified combustion. The evolution and statistical behaviour of $$\widetilde{{\varepsilon_{c\xi } }}$$ ε c ξ ~ have been analysed using a direct numerical simulation (DNS) database of statistically planar turbulent stratified flames with a globally stochiometric mixture. A parametric analysis has been conducted by considering a number of DNS cases with a varying initial root-mean-square velocity fluctuation $$u^{\prime }$$ u ′ and initial scalar integral length scale $$\ell_{\phi }$$ ℓ ϕ . The explicitly Reynolds averaged DNS data suggests that the linear relaxation model for $$\widetilde{{\varepsilon_{c\xi } }}$$ ε c ξ ~ is inadequate for most cases, but its performance appears to improve with increasing initial $$\ell_{\phi }$$ ℓ ϕ and $$u^{\prime }$$ u ′ values. An exact transport equation for $$\widetilde{{\varepsilon_{c\xi } }}$$ ε c ξ ~ has been derived from the first principle, and the budget of the unclosed terms of the $$\widetilde{{\varepsilon_{c\xi } }}$$ ε c ξ ~ transport equation has been analysed in detail. It has been found that the terms arising from the density variation, scalar-turbulence interaction, chemical reaction rate and molecular dissipation rate play leading order roles in the $$\widetilde{{\varepsilon_{c\xi } }}$$ ε c ξ ~ transport. These observations have been justified by a scaling analysis, which has been utilised to identify the dominant components of the leading order terms to aid model development for the unclosed terms of the $$\widetilde{{\varepsilon_{c\xi } }}$$ ε c ξ ~ transport equation. The performances of newly proposed models for the unclosed terms have been assessed with respect to the corresponding terms extracted from DNS data, and the newly proposed closures yield satisfactory predictions of the unclosed terms in the $$\widetilde{{\varepsilon_{c\xi } }}$$ ε c ξ ~ transport equation.

show abstract

CFDModeling of Diesel Combustion

Vogiatzaki

¹

2017

Encyclopedia of Maritime and Offshore Engineering

View full text Add to dashboard Cite

Diesel engines are the most efficient combustion engines today, playing an important role in transport of goods and passengers on land and on sea. The main drivers for the design of future engines is the control of the emissions without sacrificing their advanced fuel economy. These drivers led to important innovations in multiple components of the engine, which, however, complicated the nature of the processes taking place and increased the need for highly accurate simulation frameworks. In the current article, the focus is on the recent progress of combustion modeling of diesel engines. The major general challenges encountered are first introduced briefly and then the progress in various research areas is reported in more details. Special focus is given to the most commonly used combustion models describing their advantages as well as their shortcomings. In the end, some closing remarks are presented as guidelines for future modeling efforts.

show abstract

Large eddy simulations of the Darmstadt turbulent stratified flame series

Cited by 45 publications

References 37 publications

Large Eddy Simulation of a 100 kWth swirling oxy-coal furnace

Large Eddy Simulation of a 100 kWth swirling oxy-coal furnace

A Priori Direct Numerical Simulation Analysis of the Closure of Cross-Scalar Dissipation Rate of Reaction Progress Variable and Mixture Fraction in Turbulent Stratified Flames

CFDModeling of Diesel Combustion

Contact Info

Product

Resources

About