 | Rautmann Ch. Numerical simulation concept for low-noise wind turbine rotors: Diss. ... Dr.-Ing. / Deutsches Zentrum für Luft- und Raumfahrt, Institut für Aerodynamik und Strömungstechnik, Braunschweig. - Köln: DLR, 2017. - XXIII, 149 p. ill. - (Forschungsbericht; 2017-35). - Res. also Germ. - Bibliogr.: p.143-149. - ISSN 1434-8454
Шифр: (Pr 1120/2017-35) 02
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Summary ....................................................... vii
Zusammenfassung ................................................ ix
List of Figures ................................................ xv
List of Tables ............................................... xvii
Nomenclature .................................................. xix
1 Introduction ............................................... 1
1.1 Motivation ................................................. 1
1.2 Previous Work .............................................. 4
1.3 Objectives ................................................. 5
1.4 Structure .................................................. 6
2 Theory ..................................................... 7
2.1 Making Torque from Wind .................................... 7
2.1.1 ID Momentum Theory .................................. 8
2.1.2 Blade Element Momentum Method (BEM) ................ 10
2.1.3 Turbine Operation .................................. 12
2.2 Aerodynamics - CFD ........................................ 13
2.2.1 Governing Equations ................................ 14
2.2.2 Numerical Simulation Technique ..................... 14
2.2.3 Turbulence Modeling ................................ 15
2.3 Aeroacoustics - CAA ....................................... 17
2.3.1 General ............................................ 17
2.3.2 Acoustic Analogy ................................... 18
2.3.3 Scattering Half Plane .............................. 19
2.3.4 Governing Equations ................................ 20
2.3.5 Numerical Simulation Technique ..................... 22
2.3.6 FRPM ............................................... 23
2.3.7 Wind Turbine Noise Sources ......................... 26
3 Simulation Methods ........................................ 31
3.1 Toolchain Overview ........................................ 31
3.2 CFD ....................................................... 33
3.2.1 Mesh ............................................... 34
3.2.2 Boundary Conditions and Models ..................... 37
3.2.3 Grid Refinement Study .............................. 39
3.2.4 Validation ......................................... 42
3.3 CAA with FRPM ............................................. 43
3.3.1 Mesh ............................................... 44
3.3.2 Boundary Conditions and Models ..................... 48
3.3.3 FRPM ............................................... 49
3.3.4 Grid Refinement Study .............................. 56
3.3.5 Best Practice Aspects .............................. 58
3.4 Data Processing and Scripting ............................. 60
4 Results and Discussion .................................... 63
4.1 Validation Test Cases from ВANC-II ........................ 63
4.1.1 Test case #1 NACA0012 .............................. 64
4.1.2 Test case #2 NACA0012 .............................. 66
4.1.3 Test case #3 NACA0012 .............................. 67
4.1.4 Test case #4 NACA0012 .............................. 68
4.1.5 Test case #5 DU96-W-180 ............................ 69
4.2 Geometry Variation Strategy ............................... 71
4.2.1 Geometry ........................................... 71
4.2.2 Flow Parameters .................................... 72
4.3 Geometry Variation Results ................................ 73
4.3.1 Aerodynamics ....................................... 74
4.3.2 Aerodynamics and Acoustics ......................... 76
4.4 Relationship between Boundary Layer Values and Noise ...... 81
4.4.1 Cases with same L-over-D Ratio and different
OASPL .............................................. 81
4.4.2 Cases with different L-over-D Ratio and same
OASPL .............................................. 83
4.4.3 Further Data Analysis .............................. 85
4.5 Strategy for Low Noise Airfoils ........................... 90
5 Turbine Evaluation ........................................ 93
5.1 Method .................................................... 93
5.1.1 3D CAA Simulation .................................. 93
5.1.2 Alternative Method using 2D CAA Results ............ 95
5.2 Results and Discussion .................................... 97
5.2.1 Analysis of the NREL 5MW Reference Turbine ......... 97
5.2.2 Improvement of NREL 5MW Turbine with Low-Noise
Airfoils .......................................... 105
5.2.3 Influence of Airfoil Performance on the overall
Turbine Performance ............................... 114
5.3 Benefit of Noise-Reduction ............................... 116
6 Conclusions and Future Work .............................. 119
6.1 Impact of Results on Next-Generation Turbines ............ 123
6.2 Outlook .................................................. 124
A Appendix ................................................. 127
A.l Derivation of the BEM Method ............................. 127
A.2 Governing Equations ...................................... 131
A.3 From Governing Equations to Wave Equation ................ 132
A.4 Realizing a Liepmann Turbulence Spectrum with FRPM ....... 133
A.5 PIANO Input File for CAA Airfoil Simulations ............. 136
A.6 Modified Trailing-Edge Noise Directivity ................. 138
A.7 Additional Airfoil Geometries ............................ 141
Bibliography .................................................. 143
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