 | Martin D.Q. An aeroelastic reduced order model for dynamic response prediction to gust encounters: Diss. … Dr.-Ing. / Deutsches Zentrum für Luft- und Raumfahrt, Institut für Aeroelastik, Göttingen. - Köln: DLR, 2017. - xxiv, 169 p.: ill., tab. - (Forschungsbericht; 2017-36). - Res. also Germ. - Bibliogr.: p.159-169. - ISSN 1434-8454
Шифр: (Pr 1120/2017-36) 02
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Abstract .................................................... ххiii
1 Introduction ............................................... 1
1.1 Motivation ................................................. 1
1.2 Previous work .............................................. 3
1.3 Objectives and outline ..................................... 6
1 Theory .................................................... 11
2 Dynamic response .......................................... 13
2.1 Aeroelastic modeling ...................................... 13
2.1.1 Structural model ................................... 13
2.1.2 Aerodynamic model .................................. 14
2.1.2.1 RANS equations ................................. 15
2.1.2.2 Euler equations ................................ 16
2.1.2.3 Full potential equations ....................... 16
2.1.2.4 Doublet Lattice Method ......................... 17
2.1.3 Spatial coupling ................................... 21
2.2 Aeroelastic response ...................................... 25
2.2.1 Time domain solution ............................... 30
2.2.1.1 Temporal coupling .............................. 32
2.2.1.2 Gust modeling .................................. 33
2.2.1.3 Mesh deformation ............................... 34
2.2.2 Frequency domain solution .......................... 34
2.2.2.1 Fourier transforms and numerical
interpolation .................................. 37
2.2.2.2 Implementation and validation .................. 40
2.3 Loads recovery ........................................... 41
2.3.1 Nodal loads ........................................ 41
2.3.2 Cut loads .......................................... 42
3 Aeroelastic ROM in the linear aerodynamic region .......... 45
3.1 System identification in the frequency domain ............. 45
3.1.1 Least squares problem .............................. 46
3.1.2 Numerical implementation ........................... 55
3.2 Quasisteady correction .................................... 56
3.3 Correction modes .......................................... 56
3.4 Implementation into the gust equation ..................... 62
3.5 Aeroelastic modes ......................................... 62
4 Aeroelastic ROM in the nonlinear aerodynamic region ....... 67
4.1 General formulation for nonlinear systems ................. 67
4.1.1 Quasi linearization ................................ 68
4.1.2 Quasi linearization and Trajectory Linearization ... 70
4.1.3 Example ............................................ 75
4.2 Application to aeroelastic systems ........................ 81
4.2.1 Quasilinearization ................................. 82
4.2.2 Quasilinearization and Trajectory Linearization .... 85
II Results ................................................... 99
5 Transonic profile: NACA64A010 ............................ 101
5.1 Model description ........................................ 101
5.2 Aerodynamic boundary ..................................... 104
5.3 Linear aerodynamic region ................................ 110
5.4 Nonlinear aerodynamic region ............................. 111
5.5 ROM performance .......................................... 115
6 Free flexible aircraft: Euler equations .................. 117
6.1 Model description ........................................ 117
6.2 Linear Aerodynamic Region ................................ 121
6.3 Nonlinear Aerodynamic Region ............................. 130
6.4 ROM performance .......................................... 141
7 Free flexible aircraft: RANS equations ................... 143
7.1 Model description ........................................ 143
7.2 Free rigid aircraft ...................................... 146
7.3 Free flexible aircraft ................................... 148
7.4 ROM performance .......................................... 149
8 Conclusions .............................................. 155
8.1 Summary .................................................. 155
8.2 Outlook .................................................. 158
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