scholarly journals Relationships for maximum flame surface density and brush thickness through conditional analysis in turbulent premixed combustion

2013 ◽  
Vol 25 (7) ◽  
pp. 075108 ◽  
Author(s):  
Kang Y. Huh ◽  
Jaesung Kwon ◽  
Dongkyu Lee
Keyword(s):  
Surface Density ◽  
Conditional Analysis ◽  
Premixed Combustion ◽  
Flame Surface ◽  
Turbulent Premixed Combustion ◽  
Flame Surface Density ◽  
Turbulent Premixed

scholarly journals The evolution equation for the flame surface density in turbulent premixed combustion

1994 ◽  
Vol 278 ◽  
pp. 1-31 ◽  
Author(s):  
Arnaud Trouvé ◽  
Thierry Poinsot
Keyword(s):  
Evolution Equation ◽  
Flame Propagation ◽  
Surface Density ◽  
Turbulent Flame ◽  
Premixed Combustion ◽  
Flame Surface ◽  
Turbulent Premixed Combustion ◽  
Flame Surface Density ◽  
Propagation Effects ◽  
Turbulent Premixed

One basic effect of turbulence in turbulent premixed combustion is for the fluctuating velocity field to wrinkle the flame and greatly increase its surface area. In the flamelet theory, this effect is described by the flame surface density. An exact evolution equation for the flame surface density, called the Σ-equation, may be written, where basic physical mechanisms like production by hydrodynamic straining and destruction by propagation effects are described explicitly. Direct numerical simulation (DNS) is used in this paper to estimate the different terms appearing in the Σ-equation. The numerical configuration corresponds to three-dimensional premixed flames in isotropic turbulent flow. The simulations are performed for various mixture Lewis numbers in order to modify the strength and nature of the flame-flow coupling. The DNS-based analysis provides much information relevant to flamelet models. In particular, the flame surface density, and the source and sink terms for the flame surface density, are resolved spatially across the turbulent flame brush. The geometry as well as the dynamics of the flame differ quite significantly from one end of the reaction zone to the other. For instance, contrary to the intuitive idea that flame propagation effects merely counteract the wrinkling due to the turbulence, the role of flame propagation is not constant across the turbulent brush and switches from flame surface production at the front to flame surface dissipation at the back. Direct comparisons with flamelet models are also performed. The Bray-Moss-Libby assumption that the flame surface density is proportional to the flamelet crossing frequency, a quantity that can be measured in experiments, is found to be valid. Major uncertainties remain, however, over an appropriate description of the flamelet crossing frequency. In comparison, the coherent flame model of Marble & Broadwell achieves closure at the level of the Σ-equation and provides a more promising physically based description of the flame surface dynamics. Some areas where the model needs improvement are identified.

Flamelet perturbations and flame surface density transport in weakly turbulent premixed combustion

2016 ◽  
Vol 21 (2) ◽  
pp. 205-227 ◽  
Author(s):  
Andrei Nikolaevich Lipatnikov ◽  
Vladimir Anatolievich Sabelnikov ◽  
Shinnosuke Nishiki ◽  
Tatsuya Hasegawa
Keyword(s):  
Surface Density ◽  
Premixed Combustion ◽  
Flame Surface ◽  
Turbulent Premixed Combustion ◽  
Flame Surface Density ◽  
Turbulent Premixed

Analysis of flame surface density measurements in turbulent premixed combustion

2009 ◽  
Vol 156 (3) ◽  
pp. 657-664 ◽  
Author(s):  
Fabien Halter ◽  
Christian Chauveau ◽  
Iskender Gökalp ◽  
Denis Veynante
Keyword(s):  
Surface Density ◽  
Premixed Combustion ◽  
Flame Surface ◽  
Turbulent Premixed Combustion ◽  
Flame Surface Density ◽  
Density Measurements ◽  
Turbulent Premixed

Turbulent Premixed LES Combustion Models Based on Fractal Flame Surface Density Concepts

2014 ◽  
Author(s):  
Usman Allauddin ◽  
Roman Keppeler ◽  
Michael Pfitzner
Keyword(s):  
Numerical Simulations ◽  
Gas Turbines ◽  
Surface Density ◽  
Original Model ◽  
Premixed Combustion ◽  
Flame Surface ◽  
Flame Surface Density ◽  
Combustion Models ◽  
Fractal Characteristics ◽  
Turbulent Premixed

With increasing computational power, Large Eddy Simulation (LES) is being widely used to study and develop a better understanding of turbulent combustion. A variety of subgrid combustion models have been proposed to investigate premixed combustion in LES. One of the physical aspects that can be exploited, are the fractal characteristics of premixed flames which have been confirmed in several experimental works. In this work the performance of a simplified version of an already established sub-grid flame surface density combustion model, which is based on the fractal characteristics of the flame surface is investigated. The original model was derived on the basis of theoretical models, experimental and direct numerical simulations databases and its performance was validated with data from the available literature. The simplifications to the established flame surface density model are discussed, and its performance is validated in comparison to the original model. Secondly numerical simulations with both models at conditions typical for spark-ignition engines and industrial gas turbines are validated against experimental data. It is found that both original and simplified models are suitable for LES of low to high turbulent premixed combustion in ambient and elevated pressure conditions.

Sign in / Sign up

Export Citation Format

Share Document