Department of Flow, Heat and Combustion Mechanics
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Department of Flow, Heat and Combustion Mechanics Analysis of pre-tabulated chemistry models in flame simulations R. De Meester 1 , B. Naud 2 , U. Maas 3 , B. Merci 1 1 Ghent University – UGent, Dept. of Flow, Heat and Combustion Mechanics, Ghent, Belgium 2 Modeling and Numerical Simulation Group, Energy Dept., Ciemat, Madrid, Spain 3 Institute for Technical Thermodynamics, Karlsruhe University (TH), Germany Ghent University- UGent Test Case •Swirling Bluff Body Flame • Fuel Jet: CH 4 Swirling Annulus: Air Coflow: Air •Bluff Body: creates recirculation zone •Highly rotating collar: region of high shear →separates 2 recirculation zones + local extinction •Stoichiometric mixture fraction: 0.054 Tabulated Chemistry Models Conclusions •The progress variable in the 2D table possible to describe mixing of 2 gases at any point of reaction progress •1D table ↔ 2D table : forced diffusion flame structure ↔ diffusion and premixed flame structures •Work in progress: extension to tabulated chemistry for spray combustion Numerical Framework •1D↔2D: ≠ flow field ≠ T, and composition fields ≠ flame structure Table: 1D↔2D Flame Structure in Composition Space •1D: only Z independent parameter forced diffusion flame structure of 1D table • 2D: extra independent parameter Y(CO 2 ) diffusion and premixed flame structures Monte Carlo Flame Structure in Physical Space ( ).( ). PZ Z dZ 2 2 2 (, ).( , ). . P Z YCO Z YCO dZ dYCO •Reduce detailed chemical mechanisms to lower dimensional table •Parameterization: Mixture fraction Z: mixing of fuel and oxidizer Mass fraction Y(CO 2 ): progress of reaction •Effect of diffusion on the chemistry included through spatial gradients obtained from laminar diffusion flame calculations 1D table 2D table FLOW FIELD RANS Finite Volume COMPOSITION Scalar PDF Monte Carlo Mean Density Mean Viscosity Mean Velocities Mean Turbulent properties Chemistry table 1D: Z 2D: Z + Y(CO 2 ) 1D: 2D: Diffusion flame: → mixing + reaction Temperature Production of CO 2 Premixed flame: → reaction Tangential Velocity Mixture Fraction Mass Fraction of CO 2 Mass Fraction of OH Flame Index Experiment Calculation Connection between physical and composition space MIXING MIXING REACTION REACTION MIXING REACTION Evolution of computational particles MIXING MIXING REACTION MIXING + REACTION DIFFUSION FLAME PREMIXED FLAME
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Transcript of Department of Flow, Heat and Combustion Mechanics
Department of Flow, Heat and Combustion Mechanics
Analysis of pre-tabulated chemistry models in flame simulations R. De Meester1, B. Naud2, U. Maas3, B. Merci1
1Ghent University – UGent, Dept. of Flow, Heat and Combustion Mechanics, Ghent, Belgium2Modeling and Numerical Simulation Group, Energy Dept., Ciemat, Madrid, Spain
3Institute for Technical Thermodynamics, Karlsruhe University (TH), Germany
Ghent University-UGent
Test Case• Swirling Bluff Body Flame
• Fuel Jet: CH4 Swirling Annulus: Air Coflow: Air
• Bluff Body: creates recirculation zone
• Highly rotating collar: region of high shear
→separates 2 recirculation zones + local extinction
• Stoichiometric mixture fraction: 0.054
Tabulated Chemistry Models
Conclusions• The progress variable in the 2D table possible to describe mixing of 2 gases at any point of reaction progress
• 1D table ↔ 2D table : forced diffusion flame structure ↔ diffusion and premixed flame structures
• Work in progress: extension to tabulated chemistry for spray combustion
Numerical Framework
• 1D↔2D: ≠ flow field ≠ T, and composition fields ≠ flame structure
Table: 1D↔2D
Flame Structure in Composition Space
• 1D: only Z independent parameter forced diffusion flame structure of 1D table• 2D: extra independent parameter Y(CO2) diffusion and premixed flame structures
Monte Carlo
Flame Structure in Physical Space
( ). ( ).P Z Z dZ 2 2 2( , ). ( , ). .P Z YCO Z YCO dZ dYCO
• Reduce detailed chemical mechanisms to lower dimensional table
• Parameterization: Mixture fraction Z: mixing of fuel and oxidizer
Mass fraction Y(CO2): progress of reaction
• Effect of diffusion on the chemistry included through spatial gradients obtained from laminar diffusion flame calculations
1D table2D table
FLOW FIELD
RANS Finite Volume
COMPOSITION
Scalar PDFMonte Carlo
Mean Density Mean Viscosity
Mean Velocities Mean Turbulent properties
Chemistry table
1D: Z
2D: Z + Y(CO2)
1D:
2D:
Diffusion flame: → mixing + reaction
Temperature Production of CO2
Premixed flame: → reaction
Tangential Velocity Mixture Fraction Mass Fraction of CO2 Mass Fraction of OH Flame Index
Experiment Calculation Connection between physical and composition space
MIXING
MIXING
REACTION
REACTION
MIXING
REACTION
Evolution of computational particles
MIXING
MIXING
REACTION
MIXING + REACTION
DIFFUSIONFLAME
PREMIXEDFLAME
