Modeling stratified flames with and without shear using multiple mapping conditioning

2019 ◽  
Vol 37 (2) ◽  
pp. 2317-2324 ◽  
Author(s):  
C. Straub ◽  
A. Kronenburg ◽  
O.T. Stein ◽  
R.S. Barlow ◽  
D. Geyer
Keyword(s):  
Stratified Flames

Experimental investigation of isothermal and reacting flow characteristics downstream of axisymmetric bluff body stabilizers under stratified or fully premixed inlet mixture conditions

2020 ◽  
Author(s):  
Γεώργιος Πατεράκης
Keyword(s):  
Experimental Investigation ◽  
Turbulent Flow ◽  
Bluff Body ◽  
Operating Conditions ◽  
Reacting Flow ◽  
Wide Range ◽  
Flow Features ◽  
Air Mixing ◽  
The Impact ◽  
Stratified Flames

The current work describes an experimental investigation of isothermal and turbulent reacting flow field characteristics downstream of axisymmetric bluff body stabilizers under a variety of inlet mixture conditions. Fully premixed and stratified flames established downstream of this double cavity premixer/burner configuration were measured and assessed under lean and ultra-lean operating conditions. The aim of this thesis was to further comprehend the impact of stratifying the inlet fuelair mixture on the reacting wake characteristics for a range of practical stabilizers under a variety of inlet fuel-air settings. In the first part of this thesis, the isothermal mean and turbulent flow features downstream of a variety of axisymmetric baffles was initially examined. The effect of different shapes, (cone or disk), blockage ratios, (0.23 and 0.48), and rim thicknesses of these baffles was assessed. The variations of the recirculation zones, back flow velocity magnitude, annular jet ejection angles, wake development, entrainment efficiency, as well as several turbulent flow features were obtained, evaluated and appraised. Next, a comparative examination of the counterpart turbulent cold fuel-air mixing performance and characteristics of stratified against fully-premixed operation was performed for a wide range of baffle geometries and inlet mixture conditions. Scalar mixing and entrainment properties were investigated at the exit plane, at the bluff body annular shear layer, at the reattachment region and along the developing wake were investigated. These isothermal studies provided the necessary background information for clarifying the combustion properties and interpreting the trends in the counterpart turbulent reacting fields. Subsequently, for selected bluff bodies, flame structures and behavior for operation with a variety of reacting conditions were demonstrated. The effect of inlet fuel-air mixture settings, fuel type and bluff body geometry on wake development, flame shape, anchoring and structure, temperatures and combustion efficiencies, over lean and close to blow-off conditions, was presented and analyzed. For the obtained measurements infrared radiation, particle image velocimetry, laser doppler velocimetry, chemiluminescence imaging set-ups, together with Fouriertransform infrared spectroscopy, thermocouples and global emission analyzer instrumentation was employed. This helped to delineate a number of factors that affectcold flow fuel-air mixing, flame anchoring topologies, wake structure development and overall burner performance. The presented data will also significantly assist the validation of computational methodologies for combusting flows and the development of turbulence-chemistry interaction models.

Experimental measurements of geometric properties of turbulent stratified flames

2009 ◽  
Vol 32 (2) ◽  
pp. 1763-1770 ◽  
Author(s):  
P. Anselmo-Filho ◽  
S. Hochgreb ◽  
R.S. Barlow ◽  
R.S. Cant
Keyword(s):  
Experimental Measurements ◽  
Geometric Properties ◽  
Stratified Flames

scholarly journals Large Eddy Simulation of a Turbulent Spray Jet Flame Using Filtered Tabulated Chemistry

2020 ◽  
Vol 2020 ◽  
pp. 1-23
Author(s):  
Adrien Chatelier ◽  
Benoît Fiorina ◽  
Vincent Moureau ◽  
Nicolas Bertier
Keyword(s):  
Turbulent Flame ◽  
Propagation Speed ◽  
Jet Flame ◽  
Practical Applications ◽  
Flame Thickness ◽  
Tabulated Chemistry ◽  
Large Eddy ◽  
Turbulent Spray ◽  
Lift Off ◽  
Stratified Flames

This work presents Large Eddy Simulations of the unconfined CORIA Rouen Spray Burner, fed with liquid n-heptane and air. Turbulent combustion modeling is based on the Filtered TAbulated Chemistry model for LES (F-TACLES) formalism, designed to capture the propagation speed of turbulent stratified flames. Initially dedicated to gaseous combustion, the filtered flamelet model is challenged for the first time in a turbulent spray flame configuration. Two meshes are employed. The finest grid, where both flame thickness and wrinkling are resolved, aims to challenge the chemistry tabulation procedure. At the opposite the coarse mesh does not allow full resolution of the flame thickness and exhibits significant unresolved contributions of subgrid scale flame wrinkling. Both LES solutions are extensively compared against experimental data. For both nonreacting and reacting conditions, the flow and spray aerodynamical properties are well captured by the two simulations. More interesting, the LES predicts accurately the flame lift-off height for both fine and coarse grid conditions. It confirms that the modeling methodology is able to capture the filtered turbulent flame propagation speed in a two-phase flow environment and within grid conditions representative of practical applications. Differences, observed for the droplet temperature, seem related to the evaporation model assumptions.

Flamelet LES of turbulent premixed/stratified flames with H2 addition

2021 ◽  
Vol 230 ◽  
pp. 111428
Author(s):  
Xu Wen ◽  
Louis Dressler ◽  
Andreas Dreizler ◽  
Amsini Sadiki ◽  
Johannes Janicka ◽  
...  
Keyword(s):  
H2 Addition ◽  
Stratified Flames ◽  
Turbulent Premixed
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