Premixed Turbulent Combustion Modeling PhD student: Ehsan Yasari - PowerPoint PPT Presentation

Applied Mechanics Premixed Turbulent Combustion Modeling PhD student: Ehsan Yasari yasari@chalmers.se Supervisor: Andrei Lipatnikov Department of Applied Mechanics Chalmers University of Technology Ehsan Yasari - Gothenburg region OpenFOAM user group meeting 1 of 15

Applied Mechanics Outline • Project Description • Tools and Solver • Results • Problems and Difficulties • Possible Solutions Ehsan Yasari - Gothenburg region OpenFOAM user group meeting 2 of 15

Applied Mechanics Goals • Turbulent Flame Closure (TFC) • Flame Speed Closure (FSC) • Simulation of different premixed turbulent flames • Turbulent combustion flux and local burning velocity Ehsan Yasari - Gothenburg region OpenFOAM user group meeting 3 of 15

Applied Mechanics Tools and Solver • OpenFOAM • XiFoam solver: compressible premixed/partially- premixed combustion with turbulence modeling • Combustion model: based on Weller 1 model |-- ftEqn.H |-- UEqn.H |-- hEqn.H |-- XiFoam.C |-- huEqn.H |-- bEqn.H |-- pEqn.H |-- createFields.H `-- readCombustionProperties.H • 1 :Weller HG, Uslu S, Gosman AD, Maly RR, Herweg R, Heel B. COMODIA 94, Yokohama: JSME, 1994. p.163 Ehsan Yasari - Gothenburg region OpenFOAM user group meeting 4 of 15

Applied Mechanics TFC and FSC Model: ~ ~       2 c C     k ~ ~ ~ ~             c u c D U c D t      ~ , k t , u t ,      Pr t x x x   k k k 1 4       1 4  t U 0 . 5 u ' Da 0 . 5 u ' TFC Model    t ,    c     Taylor theory of turbulent t D t         ,   D D 1 exp    diffusion t t ,  L  2   u   L 1     2   t       L L   U U 1 exp FSC Model    t t ,  t t     L • Zimont, V.L., and Lipatnikov, A.N., 1995, Chem. Phys. Reports, Vol. 14, pp. 993-1025 • Lipatnikov, A.N., and Chomiak, J., 2002, Prog. Energy Combust. Sci., Vol. 28, pp. 1-74. Ehsan Yasari - Gothenburg region OpenFOAM user group meeting 5 of 15

Applied Mechanics Simulated Test Case High Turbulence intensity • P. Moreau, “Turbulent Flame Development in High Velocity Premixed Flow”, AIAA 15 th Aerospace Sciences Meeting, 1977 Ehsan Yasari - Gothenburg region OpenFOAM user group meeting 6 of 15

Applied Mechanics Numerical Setup • Geometry: 1300*100 mm • Mesh Independency: 325*25 , 650*50, 1300*120 • Unsteady solver • Turbulence Model: • k-e • Launder Sharma • RNG • Realizable k-e • Combustion Model: • Turbulent Flame Closure (TFC) Flame Speed Closure (FSC ) • • Boundary and Initial Conditions • Different Equivalence Ratio: 0.62, 0.80, 0.83, 0.85, 0.87, 1, 1.24 • High Turbulence intensity: k u = 100 m 2 /s 2 k b = 793 m 2 /s 2 Ehsan Yasari - Gothenburg region OpenFOAM user group meeting 7 of 15

Applied Mechanics Best Turbulent Pr and Dissipation Rate for TFC and FSC at Phi=0.80 Ehsan Yasari - Gothenburg region OpenFOAM user group meeting 8 of 15

Applied Mechanics Ehsan Yasari - Gothenburg region OpenFOAM user group meeting 9 of 15

Applied Mechanics Ehsan Yasari - Gothenburg region OpenFOAM user group meeting 10 of 15

Applied Mechanics V-shape Flame: • Lean premixed turbulent combustion • Low turbulence intensity: k = 0.1 m 2 /s 2 • F. Dinkelacker, S. Hözler “Investigation of a Turbulent Flame Speed Closure Approach for Premixed Flame Calculations”, Combustion Science and Technology, Vol. 158, pp. 321 -340, 2000 Ehsan Yasari - Gothenburg region OpenFOAM user group meeting 11 of 15

Applied Mechanics Problems and Difficulties • Time dependent term in FSC model     x t t         D D 1 exp    t t , U      input L 1     2   t       L L   U U 1 exp FSC Model    t t ,  t t     L Ehsan Yasari - Gothenburg region OpenFOAM user group meeting 12 of 15

Applied Mechanics Time Dependent term problem:     0 . 58 0 . 58   1   D t     2     U t    t   1 exp       t L L     1 exp     D     U t t       t , L t , L ~ D t 2 C k    ,   D t L   2 ~ ,  u Pr Ehsan Yasari - Gothenburg region OpenFOAM user group meeting 13 of 15

Applied Mechanics Possible Solution: dT     T ( x 1 ) T ( x ) x dx x    D ( x ) 1 exp( )  U L     dD x 1 x           ( 1 ) ( ) 1 exp( ) exp( ) D x D x x     x    dx U U U     L L L dU     U ( x 1 ) U ( x ) x dx x-1 x x+1 Ehsan Yasari - Gothenburg region OpenFOAM user group meeting 14 of 15

Applied Mechanics Thank you for your attention Ehsan Yasari - Gothenburg region OpenFOAM user group meeting 15 of 15