Gas Turbine Combustion: Alternative Fuels and Emissions

560 Pages·2010·12.018 MB·English

by  Lefebvre, Arthur H

THIRD EDITION
GAS
Turbine
Combustion
Alternative Fuels and Emissions

THIRD EDITION
GAS
Turbine
Combustion
Alternative Fuels and Emissions
Arthur H. Lefebvre
and
Dilip R. Ballal
Boca Raton London New York
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Contents
Preface ..................................................................................................................xvii
Authors .................................................................................................................xix
1. Basic Considerations ......................................................................................1
1.1 Introduction ...........................................................................................1
1.2 Early Combustor Developments .........................................................2
1.2.1 Britain ........................................................................................3
1.2.2 Germany ....................................................................................5
1.2.2.1 Jumo 004 ....................................................................5
1.2.2.2 BMW 003 ...................................................................6
1.2.3 The United States .....................................................................6
1.3 Basic Design Features ...........................................................................8
1.4 Combustor Requirements ....................................................................9
1.5 Combustor Types ................................................................................10
1.5.1 Tubular ....................................................................................11
1.5.2 Tuboannular ...........................................................................11
1.5.3 Annular ...................................................................................12
1.6 Diffuser .................................................................................................14
1.7 Primary Zone .......................................................................................15
1.8 Intermediate Zone ...............................................................................16
1.9 Dilution Zone .......................................................................................17
1.10 Fuel Preparation ..................................................................................18
1.10.1 Pressure-Swirl Atomizers ....................................................18
1.10.2 Airblast Atomizer .................................................................19
1.10.3 Gas Injection ..........................................................................20
1.11 Wall Cooling ........................................................................................20
1.11.1 Wall-Cooling Techniques ....................................................22
1.12 Combustors for Low Emissions ........................................................23
1.13 Combustors for Small Engines ..........................................................26
1.14 Industrial Chambers ...........................................................................28
1.14.1 Aeroderivative Engines .......................................................31
References .......................................................................................................33
Bibliography ....................................................................................................33
2. Combustion Fundamentals ........................................................................35
2.1 Introduction .........................................................................................35
2.1.1 Deflagration ............................................................................35
2.1.2 Detonation...............................................................................35
2.2 Classification of Flames ......................................................................36
2.3 Physics or Chemistry? ........................................................................37
v
vi Contents
2.4 Flammability Limits ...........................................................................37
2.5 Global Reaction-Rate Theory .............................................................38
2.5.1 Weak Mixtures .......................................................................39
2.5.2 Rich Mixtures .........................................................................39
2.6 Laminar Premixed Flames ................................................................41
2.6.1 Factors Influencing Laminar Flame Speed ........................41
2.6.1.1 Equivalence Ratio ...................................................41
2.6.1.2 Initial Temperature ................................................42
2.6.1.3 Pressure ...................................................................42
2.7 Laminar Diffusion Flames.................................................................42
2.8 Turbulent Premixed Flames ..............................................................43
2.9 Flame Propagation in Heterogeneous Mixtures of Fuel
Drops, Fuel Vapor, and Air ................................................................45
2.10 Droplet and Spray Evaporation .........................................................49
2.10.1 Heat-Up Period ......................................................................50
2.10.2 Evaporation Constant ...........................................................51
2.10.3 Convective Effects ................................................................52
2.10.4 Effective Evaporation Constant ..........................................52
2.10.5 Spray Evaporation .................................................................54
2.10.6 Some Recent Developments ................................................54
2.11 Ignition Theory ....................................................................................55
2.11.1 Gaseous Mixtures .................................................................55
2.11.2 Heterogeneous Mixtures .....................................................56
2.12 Spontaneous Ignition .........................................................................64
2.13 Flashback ..............................................................................................69
2.14 Stoichiometry .......................................................................................70
2.15 Adiabatic Flame Temperature ...........................................................71
2.15.1 Factors Influencing the Adiabatic Flame
Temperature ....................................................................71
2.15.1.1 Fuel/Air Ratio ......................................................71
2.15.1.2 Initial Air Temperature ......................................71
2.15.1.3 Pressure ................................................................72
2.15.1.4 Inlet-Air Vitiation ................................................72
Nomenclature .................................................................................................73
References .......................................................................................................74
Bibliography ....................................................................................................77
3. Diffusers .........................................................................................................79
3.1 Introduction .........................................................................................79
3.2 Diffuser Geometry ..............................................................................81
3.3 Flow Regimes ......................................................................................82
3.4 Performance Criteria ..........................................................................83
3.4.1 Pressure-Recovery Coefficient .............................................84
3.4.2 Ideal Pressure-Recovery Coefficient ...................................84
Contents vii
3.4.3 Overall Effectiveness .............................................................85
3.4.4 Loss Coefficient ......................................................................85
3.4.5 Kinetic-Energy Coefficient ...................................................86
3.5 Performance .........................................................................................86
3.5.1 Conical Diffusers ...................................................................87
3.5.2 Two-Dimensional Diffusers .................................................88
3.5.3 Annular Diffusers ..................................................................89
3.6 Effect of Inlet Flow Conditions .........................................................90
3.6.1 Reynolds Number ..................................................................91
3.6.2 Mach Number ........................................................................91
3.6.3 Turbulence ..............................................................................92
3.6.4 Swirl .........................................................................................93
3.7 Design Considerations .......................................................................93
3.7.1 Faired Diffusers .....................................................................93
3.7.2 Dump Diffusers .....................................................................97
3.7.2.1 Influence of Liner Depth Ratio .............................98
3.7.3 Splitter Vanes ..........................................................................99
3.7.4 Vortex-Controlled Diffuser ................................................100
3.7.5 Hybrid Diffuser ....................................................................101
3.7.6 Diffusers for Tubular and Tuboannular
Combustors .......................................................................104
3.7.7 Testing of Diffusers .............................................................105
3.8 Numerical Simulations.....................................................................106
Nomenclature ...............................................................................................108
References .....................................................................................................109
4. Aerodynamics..............................................................................................113
4.1 Introduction .......................................................................................113
4.2 Reference Quantities .........................................................................114
4.3 Pressure-Loss Parameters ................................................................114
4.4 Relationship between Size and Pressure Loss ..............................117
4.5 Flow in the Annulus .........................................................................118
4.6 Flow through Liner Holes................................................................120
4.6.1 Discharge Coefficient ..........................................................120
4.6.2 Initial Jet Angle ....................................................................123
4.7 Jet Trajectories ....................................................................................124
4.7.1 Experiments on Single Jets .................................................124
4.7.2 Penetration of Multiple Jets ................................................126
4.8 Jet Mixing ...........................................................................................129
4.8.1 Cylindrical Ducts .................................................................129
4.8.2 Rectangular Ducts ...............................................................131
4.8.2.1 Influence of Density Ratio ...................................132
4.8.3 Annular Ducts ......................................................................133
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4.9 Temperature Traverse Quality ........................................................133
4.10 Dilution Zone Design .......................................................................135
4.10.1 Cranfield Design Method ..................................................136
4.10.2 NASA Design Method .......................................................137
4.10.3 Comparison of Cranfield and NASA
Design Methods ...............................................................137
4.11 Correlation of Pattern Factor Data ..................................................138
4.12 Rig Testing for Pattern Factor ..........................................................140
4.13 Swirler Aerodynamics ......................................................................140
4.14 Axial Swirlers ....................................................................................142
4.14.1 Swirl Number ......................................................................143
4.14.2 Size of Recirculation Zone .................................................144
4.14.3 Flow Reversal ......................................................................145
4.14.4 Influence of Swirler Exit Geometry ..................................146
4.15 Radial Swirlers...................................................................................146
4.16 Flat Vanes Versus Curved Vanes ....................................................147
Nomenclature ...............................................................................................147
References .....................................................................................................149
5. Combustion Performance .........................................................................153
5.1 Introduction .......................................................................................153
5.2 Combustion Efficiency .....................................................................153
5.2.1 The Combustion Process ....................................................154
5.3 Reaction-Controlled Systems ..........................................................154
5.3.1 Burning Velocity Model ......................................................155
5.3.2 Stirred Reactor Model .........................................................159
5.4 Mixing-Controlled Systems .............................................................160
5.5 Evaporation-Controlled Systems ....................................................161
5.6 Reaction- and Evaporation-Controlled Systems ...........................165
5.7 Flame Stabilization ...........................................................................167
5.7.1 Definition of Stability Performance...................................167
5.7.2 Measurement of Stability Performance ............................168
5.7.3 Water Injection Technique ..................................................170
5.8 Bluff-Body Flameholders .................................................................173
5.8.1 Experimental Findings on Bluff-Body Flame
Stabilization ..........................................................................173
5.8.1.1 Homogeneous Mixtures ......................................173
5.8.1.2 Heterogeneous Mixtures .....................................177
5.8.2 Summary of Experimental Findings ................................179
5.9 Mechanisms of Flame Stabilization ...............................................179
5.9.1 Homogeneous Mixtures .....................................................181
5.9.2 Heterogeneous Mixtures ....................................................182
5.10 Flame Stabilization in Combustion Chambers .............................183
Contents ix
5.10.1 Influence of Mode of Fuel Injection .................................184
5.10.2 Correlation of Experimental Data ....................................185
5.11 Ignition ...............................................................................................188
5.12 Assessment of Ignition Performance .............................................189
5.13 Spark Ignition ....................................................................................190
5.13.1 The High-Energy Ignition Unit ........................................190
5.13.2 The Surface Discharge Igniter ..........................................191
5.13.2.1 Igniter Performance ..........................................192
5.13.2.2 Igniter Design ....................................................193
5.13.2.3 Igniter Life ..........................................................194
5.14 Other Forms of Ignition ...................................................................195
5.14.1 Torch Igniter ........................................................................195
5.14.2 Glow Plug .............................................................................196
5.14.3 Hot-Surface Ignition ...........................................................196
5.14.4 Plasma Jet .............................................................................197
5.14.5 Laser Ignition ......................................................................197
5.14.6 Chemical Ignition ...............................................................198
5.14.7 Gas Addition .......................................................................199
5.14.8 Oxygen Injection .................................................................199
5.15 Factors Influencing Ignition Performance .....................................199
5.15.1 Ignition System ...................................................................200
5.15.1.1 Spark Energy ......................................................200
5.15.1.2 Spark Duration ...................................................200
5.15.1.3 Sparking Rate .....................................................202
5.15.1.4 Igniter Location ..................................................202
5.15.2 Flow Variables .....................................................................203
5.15.2.1 Air Pressure ........................................................203
5.15.2.2 Air Temperature ................................................204
5.15.2.3 Air Velocity .........................................................205
5.15.2.4 Turbulence ..........................................................206
5.15.3 Fuel Parameters ...................................................................207
5.15.3.1 Fuel Type .............................................................207
5.15.3.2 Fuel/Air Ratio ....................................................207
5.15.3.3 Spray Characteristics ........................................208
5.15.3.4 Fuel Temperature ...............................................209
5.16 The Ignition Process .........................................................................209
5.16.1 Factors Influencing Phase 1 ...............................................210
5.16.2 Factors Influencing Phase 2 ...............................................210
5.16.3 Factors Influencing Phase 3 ...............................................211
5.17 Methods of Improving Ignition Performance ...............................211
5.17.1 Correlation of Experimental Data ....................................212
Nomenclature ...............................................................................................214
References .....................................................................................................216