Kroll / Schwamborn / Becker MEGADESIGN and MegaOpt - German Initiatives for Aerodynamic Simulation and Optimization in Aircraft Design

Results of the closing symposium of the MEGADESIGN and MegaOpt projects, Braunschweig, Germany, May 23 and 24, 2007
1. Auflage 2009
ISBN: 978-3-642-04093-1
Verlag: Springer
Format: PDF
Kopierschutz: Adobe DRM (»Systemvoraussetzungen)

E-Book, Englisch, 313 Seiten

This volume contains results of the German CFD initiative MEGADESIGN which combines CFD development activities from DLR, universities and aircraft industry. Based on the DLR flow solvers FLOWer and TAU the main objectives of the four-years project is to ensure the prediction accuracy with a guaranteed error bandwidth for certain aircraft configurations at design conditions, to reduce the simulation turn-around time for large-scale applications significantly, to improve the reliability of the flow solvers for full aircraft configurations in the complete flight regime, to extend the flow solvers to allow for multidisciplinary simulations and to establish numerical shape optimization as a vital tool within the aircraft design process. This volume highlights recent improvements and enhancements of the flow solvers as well as new developments with respect to aerodynamic and multidisciplinary shape optimization. Improved numerical simulation capabilities are demonstrated by several industrial applications.

Autoren/Hrsg.

Kroll, Norbert

Schwamborn, Dieter

Becker, Klaus

Rieger, Herbert

Thiele, Frank

Inhaltsverzeichnis

1;Preface;6
2;Contents;8
3;Part I Reduction of SimulationTime;11
3.1;Recent Developments of TAU Adaptation Capability;12
3.1.1;Introduction;12
3.1.2;TAU-Code Adaptation Overview;13
3.1.2.1;Grid Refinement Algorithm;14
3.1.2.2;Edge-Indicator Sensor Functions;14
3.1.2.3;Target Point Number Iteration;15
3.1.2.4;Recent Algorithmic Devolpments;16
3.1.2.5;Results;16
3.1.3;Target Functional-Based Mesh Adaption;18
3.1.3.1;Mathematical Background;18
3.1.3.2;Implementation in the DLR TAU Code;21
3.1.3.3;Results;23
3.1.4;Conclusion;26
3.1.5;References;27
3.2;Adaptive Wall Function for the Prediction of Turbulent Flows;29
3.2.1;Motivation;29
3.2.2;Formulation and Implementation;30
3.2.2.1;High-Reynolds Boundary Condition;31
3.2.2.2;Hybrid Adaptive Boundary Condition;32
3.2.3;Validation;33
3.2.3.1;Transonic Airfoil Flow: RAE 2822 Case 9;33
3.2.3.2;Transonic Wing Flow: ONERA M6;35
3.2.3.3;Industrial Conditions;36
3.2.4;Conclusion;40
3.2.5;References;41
3.3;Acceleration of CFD Processes for Transport Aircraft;42
3.3.1;Introduction;42
3.3.2;Overview;42
3.3.3;Utilization of Improved Code Features;43
3.3.4;Automatization of Numerical Process Chain;45
3.3.5;Simultaneous Approach;46
3.3.6;Summary/Conclusions;47
3.3.7;References;47
3.4;Efficient Combat Aircraft Simulations with the TAU RANS Code;48
3.4.1;Background;48
3.4.2;Objectives;50
3.4.3;TAU Code Efficiency Improvements;50
3.4.4;Polar Simulations for High Angle-of-Attack Cases;54
3.4.5;Conclusions;59
3.4.6;References;59
4;Part II Improvement of Simulation Quality;60
4.1;Universal Wall Functions for Aerodynamic Flows: Turbulence Model Consistent Design, Potential and Limitations;61
4.1.1;Introduction;61
4.1.2;Compressible RANS Equations;62
4.1.3;Turbulence Model Consistent Universal Wall Functions;63
4.1.3.1;Wall Function Formulation;64
4.1.3.2;Boundary-Layer Approximation for Universal Wall Functions;65
4.1.3.3;Model-Consistency of Universal Wall Functions and Grid-Independent Predictions;65
4.1.3.4;Flat Plate Turbulent Boundary Layer at Zero Pressure Gradient;67
4.1.4;Near-Wall Behaviour of RANS Models in Situations of Non-equilibrium Flow;68
4.1.5;NumericalMethod;69
4.1.6;Validation for Aerodynamic Flows;70
4.1.6.1;Transonic Airfoil Flows RAE-2822 Cases 9 and 10;70
4.1.6.2;Subsonic A-Airfoil in Highlift Configuration;72
4.1.6.3;Application to 3D Testcases;73
4.1.7;Combination of Wall-Functions and y+-Adaptation;74
4.1.8;Best Practice Guidelines;75
4.1.9;Conclusions;75
4.1.10;References;76
4.2;Computational Modelling of Transonic Aerodynamic Flows Using Near-Wall, Reynolds Stress Transport Models;78
4.2.1;Introduction;78
4.2.2;Computational Method;80
4.2.2.1;Turbulence Modelling;81
4.2.2.2;Numerical Method;86
4.2.3;Results and Discussion;87
4.2.3.1;RAE2822;88
4.2.3.2;ONERA M6 Wing;90
4.2.3.3;DLR-ALVAST;93
4.2.3.4;Numerical Issues;95
4.2.4;Results and Discussion;95
4.2.5;References;96
4.3;Transition Prediction for Three-Dimensional Configurations;98
4.3.1;Introduction;98
4.3.2;Description of Methods;99
4.3.2.1;Linear Stability Theory;99
4.3.2.2;Numerical Methods;99
4.3.3;Implementation and Parallelization Issues;103
4.3.4;Results;104
4.3.4.1;Parallelization Performance;104
4.3.4.2;Code Validation;105
4.3.4.3;Feasibility Study;107
4.3.5;Conclusions;109
4.3.6;References;110
4.4;Application of Transition Prediction;112
4.4.1;Introduction;112
4.4.2;Transition Prediction Coupling;114
4.4.3;Computational Results;116
4.4.4;Conclusion;124
4.4.5;References;125
4.5;Numerical Simulation Quality Assessment for Transport Aircraft;126
4.5.1;Introduction;126
4.5.2;Aspects of Accuracy;126
4.5.3;Status on Accuracy;127
4.5.3.1;Cruise Configuration Analysis;127
4.5.3.2;High Lift Configuration Analysis;130
4.5.4;Means to Improve Accuracy;133
4.5.5;Conclusions;136
4.5.6;References;136
5;Part III Fluid Structure Coupling;137
5.1;Computational Methods for Aero-Structural Analysis and Optimisation of Aircrafts Based on Reduced-Order Structural Models;138
5.1.1;Introduction;138
5.1.2;The {\it Aeroelastic Coupling Module} – Solver-Independent Coupling of Computational Fluidand Structural Dynamics Codes;140
5.1.2.1;Load/Deformation Projection for Single Beams;142
5.1.2.2;Extension of the Load/Deformation Projection to Frameworks of Beams;143
5.1.2.3;Validation against Aeroelastic Experiments;144
5.1.3;The Timoshenko-Beam Generator – Automatic Identification of Timoshenko-Beam Properties for Multi-Cellular Thin-Walled Wing Structures;146
5.1.3.1;Beam Identification Methodology;146
5.1.3.2;Preparation of Structural Optimisation Constraints;147
5.1.3.3;Quality of Beam Identifications;147
5.1.3.4;Evaluating the Structural Design Space in Consideration of Fluid-Structure Interaction;149
5.1.4;Summary;151
5.1.5;References;152
5.2;Development and Application of TAU-AN SYS Coupling Procedure;154
5.2.1;Introduction;154
5.2.2;The Process-Chain and Its Components;155
5.2.2.1;Aerodynamic Codes;156
5.2.2.2;Structure Code;157
5.2.2.3;Interpolation Module;157
5.2.2.4;Volume Mesh Deformation;161
5.2.2.5;Coupling Management;162
5.2.2.6;Validation;162
5.2.3;Study on Model Deformation under ETW Conditions;164
5.2.3.1;Structure Model;165
5.2.3.2;Results of Numerical Study;166
5.2.4;Summary and Conclusions;168
5.2.5;References;169
5.3;Fluid-Structure Coupling: Simplified Structural Model on Complex Configurations;171
5.3.1;Introduction;171
5.3.2;Short Description of WingDACC Method;171
5.3.3;Results on Cruise Configuration;174
5.3.3.1;Near Design Point;174
5.3.3.2;Off-Design;174
5.3.4;Results on High-Lift Configuration;175
5.3.4.1;Integrated Approach;176
5.3.4.2;Overlay Approach;177
5.3.5;Future Extensions;179
5.3.6;Summary/Conclusions;179
5.3.7;References;180
6;Part IV Improvement of Shape Optimization Strategies;181
6.1;Development of an Automated Artificial Neural Network for Numerical Optimization;182
6.1.1;Introduction;182
6.1.2;Assessing the Optimization Problem;183
6.1.3;Principles of Artifial Neural Networks;184
6.1.4;Application to Optimization;185
6.1.5;Investigation of Suitable Artificial Neural Network Topologies;186
6.1.6;Application to Real World Problems;189
6.1.7;Summary;191
6.1.8;References;191
6.2;modeFRONTIER c, a Framework for the Optimization of Military Aircraft Configurations;192
6.2.1;Description of modeFRONTIER Capabilities;192
6.2.2;Single and Multi-objective Strategies;195
6.2.3;Design of Experiments;195
6.2.4;Multi Objective Genetic Algorithm;196
6.2.5;Simplex;197
6.2.6;Gradient Based Algorithm, SQP;198
6.2.7;Multi Objective Game Theory;199
6.2.8;Example: modeFRONTIER Optimization with Genetic Algorithm;200
6.2.9;Example: modeFRONTIER Optimization through Adjoint RANS-Methodology;201
6.2.10;Conclusions;206
6.2.11;References;206
6.3;One-Shot Methods for Aerodynamic Shape Optimization;207
6.3.1;Introduction;207
6.3.2;One-Shot Method for Linear-Quadratic Problems;209
6.3.2.1;Approximate Reduced SQP Preconditioner for a Defect Correcting Iteration;209
6.3.2.2;Approximate prSQP Preconditioner for a Defect Correcting Iteration;211
6.3.3;Generalization to Non-linear Problems;213
6.3.4;Numerical Applications;215
6.3.4.1;RAE2822 Airfoil in Transonic Euler-Flow with FLOWer;215
6.3.4.2;High-Lift Configuration with TAU;216
6.3.5;References;219
6.4;Automatic Differentiation of FLOWer and MUGRIDO;221
6.4.1;Introduction;221
6.4.2;TAF;223
6.4.3;Automatic Differentiation of FLOWer;224
6.4.4;Automatic Differentiation of MUGRIDO;227
6.4.5;Conclusions;228
6.4.6;Appendix;228
6.4.7;References;231
6.5;Adjoint Methods for Coupled CFD-CSM Optimization;236
6.5.1;Introduction;236
6.5.2;Adjoint Formulation for Aero-Structure Coupling;237
6.5.3;Implementation;240
6.5.4;Validation and Application;241
6.5.5;Conclusion;244
6.5.6;References;244
7;Part V Aerodynamic and Multidisciplinary Optimization of 3D-Configurations;246
7.1;Aerodynamic Optimization for Cruise and High-Lift Configurations;247
7.1.1;Introduction;247
7.1.2;Gradients via Adjoint Approach;248
7.1.2.1;Primal Approach;248
7.1.2.2;Dual Approach;248
7.1.2.3;The Continuous Formulation;249
7.1.2.4;The Discrete Adjoint Approach;250
7.1.2.5;The Metric Terms;252
7.1.3;Planform Optimization of a Very Efficient Large Aircraft (VELA);252
7.1.4;Wing Shape Optimization of the DLR-F6 Configuration;254
7.1.5;Flap and Slat Settings Optimization of the DLR-F11 Aircraft;256
7.1.6;Conclusion;258
7.1.7;References;258
7.2;Aerodynamic Optimization of an UCAV Configuration;261
7.2.1;Introduction;261
7.2.2;Design Optimization Process;263
7.2.3;Tools of the Optimization Environment;265
7.2.4;Aerodynamic Optimization of a Combat Aircraft by an Evolutionary Approach;269
7.2.5;Optimization of an Aircraft Wing by a SIMPLEX Approach;274
7.2.6;Optimization of a Combat Aircraft by a MOGA Genetic Approach;278
7.2.7;Summary;282
7.2.8;References;282
7.3;Flexible Wing Optimisation Based on Shapes and Structures;284
7.3.1;Introduction;284
7.3.1.1;MDO Process Chain;285
7.3.2;Optimisation Process Chain Tools;286
7.3.2.1;CAD Geometry Handling;286
7.3.2.2;Wing Structural Model;286
7.3.2.3;Flow Solver;286
7.3.2.4;CFD/CSM Static Coupling;287
7.3.2.5;CAD Shape to Mesh Deformation Connector;287
7.3.3;Wing Optimisation Problem;288
7.3.3.1;Forces at Stationary Horizontal Flight;288
7.3.3.2;Flow Conditions;289
7.3.3.3;Design Parameters for Aerodynamic Shape and Wing Box Structure;289
7.3.3.4;Optimisation Algorithm;289
7.3.3.5;Handling of Optimisation Constraints;290
7.3.4;Optimisation Results;292
7.3.4.1;Test Optimisation;292
7.3.4.2;Final Optimisation with 13 Design Variables;294
7.3.5;Conclusion;301
7.3.6;References;302
7.4;Multidisciplinary Optimization of an UAV Combining CFD and CSM;303
7.4.1;Optimization Process;303
7.4.2;Aerodynamic Analysis and Optimization;305
7.4.3;FEMIntegration;305
7.4.4;Results;307
7.4.5;Conclusions;308
7.4.6;References;308
8;Author Index;309