Schwarz / Janicka Combustion Noise

1. Auflage 2009
ISBN: 978-3-642-02038-4
Verlag: Springer
Format: PDF
Kopierschutz: 1 - PDF Watermark

E-Book, Englisch, 291 Seiten

November, 2008 Anna Schwarz, Johannes Janicka In the last thirty years noise emission has developed into a topic of increasing importance to society and economy. In ?elds such as air, road and rail traf?c, the control of noise emissions and development of associated noise-reduction techno- gies is a central requirement for social acceptance and economical competitiveness. The noise emission of combustion systems is a major part of the task of noise - duction. The following aspects motivate research: • Modern combustion chambers in technical combustion systems with low pol- tion exhausts are 5 - 8 dB louder compared to their predecessors. In the ope- tional state the noise pressure levels achieved can even be 10-15 dB louder. • High capacity torches in the chemical industry are usually placed at ground level because of the reasons of noise emissions instead of being placed at a height suitable for safety and security. • For airplanes the combustion emissions become a more and more important topic. The combustion instability and noise issues are one major obstacle for the introduction of green technologies as lean fuel combustion and premixed burners in aero-engines. The direct and indirect contribution of combustion noise to the overall core noise is still under discussion. However, it is clear that the core noise besides the fan tone will become an important noise source in future aero-engine designs. To further reduce the jet noise, geared ultra high bypass ratio fans are driven by only a few highly loaded turbine stages.

Autoren/Hrsg.

Janicka, Johannes

Schwarz, Anna

Inhaltsverzeichnis

1;Foreword;5
2;Contents;7
3;Preface;12
4;1 Numerical RANS/URANS simulation of combustion noise;17
4.1;Introduction;18
4.2;Theoretical Background;18
4.2.1;RANS/URANS approach;19
4.2.2;Boundary conditions;20
4.2.3;RPM-CN approach;20
4.3;Results and Analysis;25
4.3.1;Indirect combustion noise;25
4.3.2;Direct combustion noise;35
4.4;Conclusions;42
4.5;References;44
5;2 Measurement and Simulation of Combustion Noise emitted from Swirl Burners;48
5.1;Introduction;48
5.2;Theoretical Background;50
5.2.1;Experimental Setup;50
5.2.2;Numerical Methods;52
5.3;Results and Analysis;56
5.3.1;Experiment;56
5.3.2;Numerical Simulation;64
5.4;Conclusions;74
5.5;References;75
6;3 Modeling of noise sources in combustion processes via Large-Eddy Simulation ;78
6.1;Introduction;78
6.2;Theoretical Background;79
6.2.1;Non-Premixed Flames;80
6.2.2;Partially Premixed Flames;82
6.2.3;Premixed Flames;83
6.2.4;LES/CAA Hybrid Approach;85
6.3;Results and Analysis;88
6.3.1;Open, Non-Premixed Jet Flames;88
6.3.2;Model Combustor (Partially Premixed Flames);92
6.3.3;Tecflam Burner (Premixed Flames);96
6.3.4;LES/CAA Coupling;98
6.4;Summary and Conclusions;100
6.5;References;101
7;4 Modelling of the Sound Radiation from Flames by means of Acoustic Equivalent Sources;104
7.1;Introduction;104
7.2;Theoretical Background;105
7.2.1;Hybrid Approach;105
7.2.2;Equivalent Source Method (ESM);107
7.2.3;Boundary Element Method (BEM);108
7.2.4;Numerical Simulation of the Flames;110
7.3;Results and Analysis;110
7.3.1;Numerical Aspects of the Hybrid Method;110
7.3.2;Location of the Control Surface;117
7.3.3;Inclusion of Ground Effects;117
7.3.4;Measurement of the Flame;119
7.3.5;Results of the Simulation and Comparison with the Measurement;120
7.3.6;Sound Propagation in a Non-Homogeneous Medium;122
7.4;Conclusions;134
7.5;References;135
8;5 Investigation of the Correlation of Entropy Waves and Acoustic Emission in Combustion Chambers;139
8.1;Introduction;140
8.2;Theoretical Background, Test Specification and Data Analysis;140
8.2.1;Test Specification and Data Analysis;143
8.3;Results and Discussion;148
8.3.1;Entropy Wave Generator Test Rig (EWG);148
8.3.2;Combustor Test Rig;151
8.4;Conclusions;155
8.5;References;156
9;6 Influence of boundary conditions on the noise emission of turbulent premixed swirl flames;161
9.1;Introduction;162
9.2;Theory and Methods;163
9.2.1;Calculation of the acoustic power spectrum;163
9.2.2;Modeling of the spectral heat-release;166
9.2.3;Coherence volume;170
9.2.4;Acoustic power spectrum of an unconfined flame;171
9.2.5;Simulation of confined flames;171
9.2.6;Experimental setup and measurement techniques;175
9.3;Results and Analysis;180
9.3.1;Validation of the noise-model for unconfined flames;180
9.3.2;Adiabatic flames;182
9.3.3;Unconfined flames, modeling based on CFD-data;182
9.3.4;Sound emission from a complex combustion system into the environment;183
9.4;Conclusions;184
9.5;References;185
10;7 Theoretical and Numerical Analysis of Broadband Combustion Noise;189
10.1;Introduction;189
10.2;Aeroacoustic theories to compute combustion generated noise;192
10.2.1;Acoustic analogies based on a scalar wave equation;192
10.2.2;Acoustic perturbation equations for reacting flows (APE-RF);193
10.2.3;Summary of the APE-RF formulation;196
10.2.4;Source term formulations;197
10.2.5;Rayleigh's criterion for acoustic wave amplification;200
10.3;Hybrid CFD/APE-RF method to simulate combustion noise;201
10.3.1;CFD/CAA interface conditions;201
10.3.2;Numerical methods used in the CAA;210
10.4;Results and Analysis: Application of the APE-RF system to open turbulent flames;211
10.4.1;H3 Flame: A non-premixed open turbulent flame;211
10.4.2;Premixd Methane Flame;213
10.4.3;DLR-A Flame: A non-premixed open turbulent flame;218
10.5;Summary and Conclusions ;223
10.6;Acknowledgments;225
10.7;References;225
11;8 Investigations Regarding the Simulation of Wall Noise Interaction and Noise Propagation in Swirled Combustion Chamber Flows;230
11.1;Introduction;230
11.2;Theoretical background;233
11.2.1;Mathematical models;233
11.2.2;Numerical Method;234
11.2.3;Intensity-based analysis of the result;238
11.3;Results and Discussion;240
11.3.1;The entropy wave generator (EWG) model experiment;240
11.3.2;Swing-off response of a premixed swirl combustor flow;244
11.3.3;10 kW model combustion system with 17 mm exit nozzle;246
11.4;Conclusion;248
11.5;References;250
12;9 Direct Numerical Simulations of turbulent flames to analyze flame/acoustic interactions;252
12.1;9.1 Introduction;252
12.2;9.2 Theoretical Background, Numerical methods and procedure;255
12.3;9.3 Flame/acoustics interactions investigated with DNS;266
12.4;9.4 Post-processing challenge: AnaFlame;274
12.5;9.5 Conclusions and perspectives;276
12.6;References;279
13;10 Localization of Sound Sources in Combustion Chambers;282
13.1;Introduction;282
13.2;Theoretical Background;284
13.2.1;Theory of Nearfield Acoustic Holography;284
13.2.2;Sound Pressure Field in the Combustion Chamber without Mean Flow;285
13.2.3;Modal Composition of G ;286
13.2.4;Sound Pressure Field in the Combustion Chamber with Mean Flow;288
13.2.5;Reflection at the Combustion Chamber Outlet;289
13.2.6;Reconstruction of Sound Sources;290
13.3;Results and Analysis;293
13.3.1;Optimization of the Sensor Arrangement;294
13.3.2;Effect of Noise on the Reconstruction Accuracy;297
13.3.3;Reconstruction of Sound Sources not located on assumed Source Distribution;298
13.3.4;Effect of Reflection at the Combustion Chambers Outlet;300
13.3.5;Effect of Mean Flow;301
13.4;Conclusion;302
13.5;References;303