Combustion Noise (eBook)

Foreword 5
Contents 7
Preface 12
1 Numerical RANS/URANS simulation of combustion noise 17
Introduction 18
Theoretical Background 18
RANS/URANS approach 19
Boundary conditions 20
RPM-CN approach 20
Results and Analysis 25
Indirect combustion noise 25
Direct combustion noise 35
Conclusions 42
References 44
2 Measurement and Simulation of Combustion Noise emitted from Swirl Burners 48
Introduction 48
Theoretical Background 50
Experimental Setup 50
Numerical Methods 52
Results and Analysis 56
Experiment 56
Numerical Simulation 64
Conclusions 74
References 75
3 Modeling of noise sources in combustion processes via Large-Eddy Simulation 78
Introduction 78
Theoretical Background 79
Non-Premixed Flames 80
Partially Premixed Flames 82
Premixed Flames 83
LES/CAA Hybrid Approach 85
Results and Analysis 88
Open, Non-Premixed Jet Flames 88
Model Combustor (Partially Premixed Flames) 92
Tecflam Burner (Premixed Flames) 96
LES/CAA Coupling 98
Summary and Conclusions 100
References 101
4 Modelling of the Sound Radiation from Flames by means of Acoustic Equivalent Sources 104
Introduction 104
Theoretical Background 105
Hybrid Approach 105
Equivalent Source Method (ESM) 107
Boundary Element Method (BEM) 108
Numerical Simulation of the Flames 110
Results and Analysis 110
Numerical Aspects of the Hybrid Method 110
Location of the Control Surface 117
Inclusion of Ground Effects 117
Measurement of the Flame 119
Results of the Simulation and Comparison with the Measurement 120
Sound Propagation in a Non-Homogeneous Medium 122
Conclusions 134
References 135
5 Investigation of the Correlation of Entropy Waves and Acoustic Emission in Combustion Chambers 139
Introduction 140
Theoretical Background, Test Specification and Data Analysis 140
Test Specification and Data Analysis 143
Results and Discussion 148
Entropy Wave Generator Test Rig (EWG) 148
Combustor Test Rig 151
Conclusions 155
References 156
6 Influence of boundary conditions on the noise emission of turbulent premixed swirl flames 161
Introduction 162
Theory and Methods 163
Calculation of the acoustic power spectrum 163
Modeling of the spectral heat-release 166
Coherence volume 170
Acoustic power spectrum of an unconfined flame 171
Simulation of confined flames 171
Experimental setup and measurement techniques 175
Results and Analysis 180
Validation of the noise-model for unconfined flames 180
Adiabatic flames 182
Unconfined flames, modeling based on CFD-data 182
Sound emission from a complex combustion system into the environment 183
Conclusions 184
References 185
7 Theoretical and Numerical Analysis of Broadband Combustion Noise 189
Introduction 189
Aeroacoustic theories to compute combustion generated noise 192
Acoustic analogies based on a scalar wave equation 192
Acoustic perturbation equations for reacting flows (APE-RF) 193
Summary of the APE-RF formulation 196
Source term formulations 197
Rayleigh's criterion for acoustic wave amplification 200
Hybrid CFD/APE-RF method to simulate combustion noise 201
CFD/CAA interface conditions 201
Numerical methods used in the CAA 210
Results and Analysis: Application of the APE-RF system to open turbulent flames 211
H3 Flame: A non-premixed open turbulent flame 211
Premixd Methane Flame 213
DLR-A Flame: A non-premixed open turbulent flame 218
Summary and Conclusions 223
Acknowledgments 225
References 225
8 Investigations Regarding the Simulation of Wall Noise Interaction and Noise Propagation in Swirled Combustion Chamber Flows 230
Introduction 230
Theoretical background 233
Mathematical models 233
Numerical Method 234
Intensity-based analysis of the result 238
Results and Discussion 240
The entropy wave generator (EWG) model experiment 240
Swing-off response of a premixed swirl combustor flow 244
10 kW model combustion system with 17 mm exit nozzle 246
Conclusion 248
References 250
9 Direct Numerical Simulations of turbulent flames to analyze flame/acoustic interactions 252
9.1 Introduction 252
9.2 Theoretical Background, Numerical methods and procedure 255
9.3 Flame/acoustics interactions investigated with DNS 266
9.4 Post-processing challenge: AnaFlame 274
9.5 Conclusions and perspectives 276
References 279
10 Localization of Sound Sources in Combustion Chambers 282
Introduction 282
Theoretical Background 284
Theory of Nearfield Acoustic Holography 284
Sound Pressure Field in the Combustion Chamber without Mean Flow 285
Modal Composition of G 286
Sound Pressure Field in the Combustion Chamber with Mean Flow 288
Reflection at the Combustion Chamber Outlet 289
Reconstruction of Sound Sources 290
Results and Analysis 293
Optimization of the Sensor Arrangement 294
Effect of Noise on the Reconstruction Accuracy 297
Reconstruction of Sound Sources not located on assumed Source Distribution 298
Effect of Reflection at the Combustion Chambers Outlet 300
Effect of Mean Flow 301
Conclusion 302
References 303