Combustor Model Simulation Combustion Fundamentals Final Project presentation. Presented By :Sudhir Kulkarni Dec. 13, 2005. 11/17/2018

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. 11/17/2018

As-Is…… Combustor geometry : Fuel : C3H8 i.e. Propane . Oxidant : O2+N2 i.e. Air O2- 21% , N2- 79 % Basic requirement in formulation is to look for the Fluent Models available for combustion 11/17/2018

Basics : R C3H8=A exp(-E/RT) [C3H8]0.1 [O2]1.65 Ữt = ρCỮ k2/ε 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 11/17/2018

Combustor & Meshing Combustor Layout Air Exhaust Fuel Combustor Layout As the flow is axisymmetric 2D Quadrilateral Mesh is generated 11/17/2018

Fluent Formulation Solver : Viscous Model : Species Model 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 11/17/2018

Fluent Formulation Materials : Boundary conditions : 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 11/17/2018

Fluent Formulation Initialization : Solution Model : Solved for Temperature : 1500 K Solution Model : Solved for Energy Equation Turbulence Reaction rates for elements Iterations : Convergence took 600 iterations. 11/17/2018

Results : Velocity contours Two circulation zones Central recirculation zone created by the fuel jet Confined within annular recirculation zone by the air jet 11/17/2018

Results : Velocity radial spread 11/17/2018

Results : Temperature Contours Follows the velocity contours High temperature is formed along the axis 11/17/2018

Results : Temperature Axial spread Rapid burning of fuel in very small section of the combustor. 11/17/2018

Results : Mass fraction Contours C3H8 11/17/2018

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. 11/17/2018

What Next ? Simulation of Gas turbine combustor…. 11/17/2018

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. 11/17/2018

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 . 11/17/2018

Thanking You ! Combustion Fundamentals Final Project presentation. Presented By :Sudhir Kulkarni Dec. 13, 2005. 11/17/2018