Index
1
1
Flameless combustion of hydrogen-rich fuels ... 3
1.1 Introduction ... 3
1.2 MILD or HiTAC or flameless combustion... 5
1.3 MILD combustion of H2-containing fuels ... 12
1.4 NO formation and control in combustion chamber ... 13
2
Computational Fluid Dynamics ... 20
2.1 Introduction ... 20
2.2 Conservation equations for reacting flows... 22
2.3 Constitutive equations... 24
2.4 Turbulent combustion... 28
2.4.1 Interaction between flames and turbulence ... 28
2.4.2 Elementary description of turbulence... 29
2.4.3 Computational approaches for turbulent combustion... 30
2.4.4 RANS simulations for turbulent combustion ... 32
2.4.4.1 Averaging the balance equations ... 32
2.4.4.2 Unclosed terms in Favre averaged balance equations ... 33
2.4.5 Turbulence models ... 34
2.4.5.1 Gradient transport models ... 34
2.4.5.2 Reynolds stress transport model... 35
2.5 Mean reaction rates combustion models ... 36
2.5.1 Definition of the problem ... 36
2.5.2 Finite Rate model (FR) ... 38
2.5.3 Eddy Break-up model (EBU by Spalding, 1971, 1976) ... 38
2.5.4 Eddy Dissipation Model (EDM, Magnussen and Hjertager, 1976) ... 39
2.5.5 Eddy Dissipation/ Finite Rate model (ED/FR)... 40
2.5.6 Eddy Dissipation Concept model (EDC by Magnussen, 1981, 1983,1999,2005) 41 2.5.7 EDC energy cascade model and fine structures ... 44
2.5.8 Molecular mixing processes ... 49
2.5.9 Reaction process ... 50
2.6 Other combustion models ... 52
2.6.1 Models for primitive variables determination ... 52
2.6.2 Presumed PDF for infinitely fast chemistry model ... 52
2.6.2.1 Flamelet Approach for finite rate chemistry model (Peters, 1984, 1986).... 55
2.6.3 The Composition PDF Transport model ... 58
2.7 Radiation models ... 59
2.7.1 Radiative properties evaluation ... 60
3
Experimental equipment and campaign ... 61
3.1 FLOX® burner ... 61
3.1.1 The burner ... 61
Index
2
3.1.3 Design of the cooling system for experimental campaign n°2... 67
3.1.4 Experimental campaign n°1 ... 69
3.1.5 Results of experimental campaign n°1 ... 69
3.1.6 Experimental campaign n°2 ... 72
3.1.7 Results of experimental campaign n°2 ... 73
3.2 Laboratory scale burner ... 77
3.2.1 Description ... 77
3.2.2 The experimental activity ... 79
4
Numerical simulations ... 81
4.1 FLOX burner numerical simulation... 81
4.1.1 The experimental runs simulated... 81
4.1.2 Numerical domain and grid ... 82
4.1.3 Boundary conditions... 84
4.1.4 Turbulence model ... 88
4.1.5 Combustion models ... 88
4.1.6 Kinetic schemes... 89
4.1.7 Radiation model and radiative properties evaluation ... 90
4.1.8 Molecular diffusivity of species ... 91
4.2 Laboratory scale burner numerical simulations ... 93
4.2.1 The experimental runs ... 93
4.2.2 Numerical domain and grid ... 94
4.2.3 Boundary conditions... 96
4.2.4 Mathematical models... 97
5
Results... 99
5.1 Results on FLOX® experimental campaign n°1 ... 99
5.1.1 Effect of turbulence/chemistry interaction models and kinetic mechanisms ... 99
5.1.2 Effect of H2 addition to the fuel ... 102
5.1.3 NO prediction ... 106
5.1.4 Effect of molecular diffusion... 107
5.2 Results on FLOX® experimental campaign n°2 ... 109
5.2.1 Velocity field ... 109
5.2.2 Effect of kinetic mechanisms/combustion model... 110
5.2.3 Effect of H2 addition to the fuel ... 113
5.2.4 Effect of molecular diffusivity ... 115
5.2.5 NO prediction ... 118
5.3 Results on laboratory scale burner ... 124
5.3.1 Effect of kinetic mechanisms/combustion model and molecular diffusivity 124 5.3.2 Effect of dilution ratio ... 128
5.3.3 NO prediction ... 133
