Department of Flow, Heat and Combustion Mechanics

1. REACTION MIXING MIXING REACTION REACTION MIXING Analysis of pre-tabulated chemistry models in flame simulations R. De Meester1, B. Naud2,U. Maas3, B. Merci11Ghent University – UGent, Dept. of Flow, Heat and Combustion Mechanics, Ghent, Belgium2Modeling and Numerical Simulation Group, Energy Dept., Ciemat, Madrid, Spain3Institute for Technical Thermodynamics, Karlsruhe University (TH), Germany Ghent University-UGent Department of Flow, Heat and Combustion Mechanics Table: 1D↔2D Tabulated Chemistry Models Temperature • 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 Production of CO2 1D table 2D table Test Case Numerical Framework • Swirling Bluff Body Flame • Fuel Jet: CH4Swirling 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 Mean Density Mean Viscosity 1D: 2D: FLOW FIELD RANS Finite Volume COMPOSITION Scalar PDFMonte Carlo Chemistry table 1D: Z 2D: Z + Y(CO2) Mean Velocities Mean Turbulent properties Flame Structure in Physical Space Tangential Velocity Mixture Fraction Mass Fraction of CO2 Mass Fraction of OH Flame Index Premixed flame:→ reaction Diffusion flame:→ mixing + reaction • 1D↔2D: ≠ flow field ≠ T, r and composition fields ≠ flame structure Flame Structure in Composition Space Monte Carlo Connection between physical and composition space Evolution of computational particles Experiment Calculation PREMIXEDFLAME REACTION MIXING MIXING + REACTION DIFFUSIONFLAME • 1D: only Z independent parameter forced diffusion flame structure of 1D table • 2D: extra independent parameter Y(CO2) diffusion and premixed flame structures MIXING 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