Deterministic Multiple Mapping Conditioning (MMC) applied to a turbulent flame in Large Eddy Simulation (LES)

2013 ◽  
Vol 34 (1) ◽  
pp. 1213-1221 ◽  
Author(s):  
C.B. Devaud ◽  
I. Stanković ◽  
B. Merci
Keyword(s):  
Large Eddy Simulation ◽  
Turbulent Flame ◽  
Eddy Simulation ◽  
Large Eddy

Laminar-to-turbulent flame transition and cycle-to-cycle variations in large eddy simulation of spark-ignition engines

2020 ◽  
pp. 146808742096234
Author(s):  
Yunde Su ◽  
Derek Splitter ◽  
Seung Hyun Kim
Keyword(s):  
Large Eddy Simulation ◽  
Early Stage ◽  
Turbulent Flame ◽  
Transition Process ◽  
Spark Ignition ◽  
Transition Model ◽  
Flame Kernel ◽  
Eddy Simulation ◽  
Proposed Model ◽  
Large Eddy

This paper investigates the effect of laminar-to-turbulent flame transition modeling on the prediction of cycle-to-cycle variations (CCVs) in large eddy simulation (LES) of spark-ignition (SI) engines. A laminar-to-turbulent flame transition model that describes the non-equilibrium sub-filter flame speed evolution during an early stage of flame kernel growth is developed. In the present model, the flame transition is characterized by the flame kernel size at which the flame transition ends, defined here as the flame transition scale. The proposed model captures the effects that variations in a turbulent flow field have on the evolution of early-stage burning rates, through variations in the flame transition scale. The proposed flame transition model is combined with the front propagation formulation (FPF) method and a spark-ignition model to predict CCVs in a gasoline direct injection SI engine. It is found that multi-cycle LES with the proposed flame transition model reproduces experimentally-observed CCVs satisfactorily. When the transition model is not considered or when variations in the transition process are neglected, CCVs are significantly under-predicted for the case considered here. These results indicate the importance of modeling the laminar-to-turbulent flame transition and the effect of turbulence on the transition process, when predicting CCVs, under certain engine conditions. The LES results are also used to analyze sources for variations in the flame transition. It is found, for the present engine case, that the most important source is the cycle-to-cycle variation in the turbulence dissipation rate, which is used to measure the strength of turbulence in the proposed model, near a spark plug. The large-scale velocity field and the variations of the laminar flame speed due to the mixture composition and thermal stratification are also found to be important factors to contribute to the variations in the flame transition.

Large-eddy simulation modeling of turbulent flame synthesis of titania nanoparticles using a bivariate particle description

AIChE Journal ◽  
2013 ◽  
Vol 60 (2) ◽  
pp. 459-472 ◽  
Author(s):  
Yonduck Sung ◽  
Venkat Raman ◽  
Heeseok Koo ◽  
Maulik Mehta ◽  
Rodney O. Fox
Keyword(s):  
Large Eddy Simulation ◽  
Simulation Modeling ◽  
Turbulent Flame ◽  
Titania Nanoparticles ◽  
Flame Synthesis ◽  
Eddy Simulation ◽  
Large Eddy

Large eddy simulation of a turbulent flame using tabulated chemistry with a novel multivariate PDF

2019 ◽  
Vol 33 (5) ◽  
pp. 181-201 ◽  
Author(s):  
David Jesch ◽  
Alija Bevrnja ◽  
Francesca di Mare ◽  
Johannes Janicka ◽  
Amsini Sadiki
Keyword(s):  
Large Eddy Simulation ◽  
Turbulent Flame ◽  
Eddy Simulation ◽  
Tabulated Chemistry ◽  
Large Eddy

Implementation of the Thickened Flame Model for Large Eddy Simulation of Turbulent Premixed Combustion in a Commercial Solver

2007 ◽  
Author(s):  
Ludovic Durand ◽  
Wolfgang Polifke
Keyword(s):  
Large Eddy Simulation ◽  
Unstructured Grids ◽  
Turbulent Flame ◽  
Premixed Combustion ◽  
Turbulent Premixed Combustion ◽  
Turbulent Flame Speed ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Commercial Solver ◽  
Turbulent Premixed

The Thickened Flame model of Colin et al. for Large Eddy Simulation of turbulent premixed combustion has been implemented in a general purpose, commercial CFD solver. In this model, the computation of the filtered reaction rate involves a third order derivative operator acting on the velocity field. The evaluation of this operator is non-trivial even for cartesian grids, and indeed quite difficult for unstructured grids. Strategies to overcome these difficulties are discussed in the paper; in order to ease the implementation for unstructured grids in a commercial solver, a slight modification of the original thickened flame model is proposed. Both the original and the modified version of the thickened flame model are validated against experimental data (velocity distribution and flame position) for a turbulent, bluff-body stabilized, premix flame. A comparison against results obtained with the Turbulent Flame speed Closure LES-model proposed by Flohr and Pitsch is also presented.

scholarly journals Large Eddy Simulation of a Swirl-Stabilized Pilot Combustor from Conventional to Flameless Mode

2016 ◽  
Vol 2016 ◽  
pp. 1-16 ◽  
Author(s):  
Ehsan Fooladgar ◽  
C. K. Chan
Keyword(s):  
High Temperature ◽  
Large Eddy Simulation ◽  
Turbulent Flame ◽  
Combustion Model ◽  
Lean Premixed Combustion ◽  
Eddy Simulation ◽  
Stirred Reactor ◽  
Wide Range ◽  
Large Eddy ◽  
One Step

This paper investigates flame and flow structure of a swirl-stabilized pilot combustor in conventional, high temperature, and flameless modes by means of a partially stirred reactor combustion model to provide a better insight into designing lean premixed combustion devices with preheating system. Finite rate chemistry combustion model with one step tuned mechanism and large eddy simulation is used to numerically simulate six cases in these modes. Results show that moving towards high temperature mode by increasing the preheating level, the combustor is prone to formation of thermalNOxwith higher risks of flashback. In addition, the flame becomes shorter and thinner with higher turbulent kinetic energies. On the other hand, towards the flameless mode, leaning the preheated mixture leads to almost thermalNOx-free combustion with lower risk of flashback and thicker and longer flames. Simulations also show qualitative agreements with available experiments, indicating that the current combustion model with one step tuned mechanisms is capable of capturing main features of the turbulent flame in a wide range of mixture temperature and equivalence ratios.

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