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Combustor Model Simulation

Combustor Model Simulation. Combustion Fundamentals Final Project presentation . Presented By :Sudhir Kulkarni Dec. 13, 2005. Motivation.

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Combustor Model Simulation

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  1. Combustor Model Simulation Combustion Fundamentals Final Project presentation. Presented By :Sudhir Kulkarni Dec. 13, 2005.

  2. Motivation • Accurate analysis of velocity field represents flow characteristics & turbulent mixing properties ,when coupled with chemical kinetics defines combustion process which represents temperature distribution in flow. • To utilize CFD software FLUENT coupling turbulence mechanism with chemical kinetics to simulate velocity and temperature distribution in a combustor. • Check the simulation output with the available results.

  3. As-Is…… • Combustor geometry : • Fuel : C3H8 i.e. Propane . • Oxidant : O2+N2i.e. Air O2- 21% , N2- 79 % • Basic requirement in formulation is to look for the Fluent Models available for combustion

  4. Basics : • One step global mechanism for Propane oxidation C3H8+ 5(CO2+3.76 N2)= 3CO2 + 4H20 + (5x3.76) N2 • Reaction Rate : A=4.836 e+09 ,E= 1.256 e+08 Arrhenius Law, Boltzman Constant, Rate Factors • Turbulent Viscosity: R C3H8=A exp(-E/RT) [C3H8]0.1 [O2]1.65 Ữt = ρCỮ k2/ε k: Turbulent Kinetic energy ε : Dissipation rate

  5. Combustor & Meshing Exhaust Air Fuel Combustor Layout As the flow is axisymmetric 2D Quadrilateral Mesh is generated

  6. Fluent Formulation • Solver : • Steady state , Axisymmetric, Segregated • Viscous Model : • K-Epsilon Model : RNG model Opted for simulation • Reynolds Stress equation • Species Model • Species Transport : Being General , Opted for simulation . • Premixed • Non-Premixed • Partially Premixed • Turbulence and chemistry interactions • Eddy-dissipation/Finite rate : Opted for simulation • Eddy dissipation

  7. Fluent Formulation • Materials : • Propane –air Mixture : To utilize the mixture properties from fluent database • Heat capacities of individual fluid are set for temperature dependent polynomial considering the temperature variation in the zone. • Boundary conditions : • Air-Inlet :- Axial Component of velocity : 0.75 -Radial component of velocity : 0.25 [ To match with the geometry of the combustor ] - Turbulent specification : Intensity & hydraulic diameter : Opted for simulation Intensity & length scale

  8. Fluent Formulation • Initialization : • Temperature : 1500 K • Solution Model : Solved for • Energy Equation • Turbulence • Reaction rates for elements • Iterations : • Convergence took 600 iterations.

  9. Results : Velocity contours • Two circulation zones • Central recirculation zone created by the fuel jet • Confined within annular recirculation zone by the air jet

  10. Results : Velocity radial spread

  11. Results : Temperature Contours • Follows the velocity contours • High temperature is formed along the axis

  12. Results : Temperature Axial spread • Rapid burning of fuel in very small section of the combustor.

  13. Results : Mass fraction Contours O2 N2 C3H8

  14. What Next ? • Prediction Of NOx • NOx concentration depends mainly on the temperature distribution and hence on the turbulence as well. • Formulation of This combustion model with velocity and temperature can be well utilised for NOx evaluation.

  15. What Next ? • Simulation of Gas turbine combustor….

  16. Learning's…… • Formulating the combustion problem for the Fluent simulation. • Preparation of geometry and mesh formation in Gambit (in consideration with the fluent facilities) • Set the combustion problem in Fluent .Initiate and solve the simulation.

  17. References …… • Lei-Yong Jiang and Ian Campbell .”A critical evaluation of NOx modeling in a model combustor”. J. Engineering for gas turbine and power July 2005 Vol 127 P 483-91. • FLUENT Tutorials • Dr. Kirk , Class Notes .

  18. Thanking You ! Combustion Fundamentals Final Project presentation. Presented By :Sudhir Kulkarni Dec. 13, 2005.

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