Cover image for Low-speed aerodynamics : from wing theory to panel methods
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Low-speed aerodynamics : from wing theory to panel methods
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New York : McGraw-Hill, 1991
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9780070504462
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30000000182521 TL570.K37 1991 Open Access Book Book
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Summary

Summary

Low-Speed Aerodynamics is important in the design and operation of aircraft flying at low Mach number, as well as for ground and marine vehicles. This book offers a modern treatment of the subject, both the theory of inviscid, incompressible, and irrotational aerodynamics and the computational techniques now available to solve complex problems. A unique feature of the text is the computational approach (from a single vortex element to a three-dimensional panel formulation) interwoven throughout. Thus, the reader can learn about classical methods to solve real world aerodynamics problems. This second edition includes a new chapter on the laminar boundary layer, the latest versions of computational technique, and additional coverage of interaction problems. It includes a systematic treatment of two-dimensional panel methods and a detailed presentation of computational techniques for three-dimensional and unsteady flows. With extensive illustrations and examples, this book will be useful for senior and beginning graduate-level courses as well as a useful reference for practicing engineers. Book jacket.


Author Notes

Joseph Katz is a Professor of Aerospace Engineering and Engineering Mechanics at San Diego State University
Allen Plotkin is a Professor of Aerospace Engineering and Engineering Mechanics at San Diego State University


Table of Contents

Prefacep. xiii
Preface to the First Editionp. xv
1 Introduction and Backgroundp. 1
1.1 Description of Fluid Motionp. 1
1.2 Choice of Coordinate Systemp. 2
1.3 Pathlines, Streak Lines, and Streamlinesp. 3
1.4 Forces in a Fluidp. 4
1.5 Integral Form of the Fluid Dynamic Equationsp. 6
1.6 Differential Form of the Fluid Dynamic Equationsp. 8
1.7 Dimensional Analysis of the Fluid Dynamic Equationsp. 14
1.8 Flow with High Reynolds Numberp. 17
1.9 Similarity of Flowsp. 19
2 Fundamentals of Inviscid, Incompressible Flowp. 21
2.1 Angular Velocity, Vorticity, and Circulationp. 21
2.2 Rate of Change of Vorticityp. 24
2.3 Rate of Change of Circulation: Kelvin's Theoremp. 25
2.4 Irrotational Flow and the Velocity Potentialp. 26
2.5 Boundary and Infinity Conditionsp. 27
2.6 Bernoulli's Equation for the Pressurep. 28
2.7 Simply and Multiply Connected Regionsp. 29
2.8 Uniqueness of the Solutionp. 30
2.9 Vortex Quantitiesp. 32
2.10 Two-Dimensional Vortexp. 34
2.11 The Biot-Savart Lawp. 36
2.12 The Velocity Induced by a Straight Vortex Segmentp. 38
2.13 The Stream Functionp. 41
3 General Solution of the Incompressible, Potential Flow Equationsp. 44
3.1 Statement of the Potential Flow Problemp. 44
3.2 The General Solution, Based on Green's Identityp. 44
3.3 Summary: Methodology of Solutionp. 48
3.4 Basic Solution: Point Sourcep. 49
3.5 Basic Solution: Point Doubletp. 51
3.6 Basic Solution: Polynomialsp. 54
3.7 Two-Dimensional Version of the Basic Solutionsp. 56
3.8 Basic Solution: Vortexp. 58
3.9 Principle of Superpositionp. 60
3.10 Superposition of Sources and Free Stream: Rankine's Ovalp. 60
3.11 Superposition of Doublet and Free Stream: Flow around a Cylinderp. 62
3.12 Superposition of a Three-Dimensional Doublet and Free Stream: Flow around a Spherep. 67
3.13 Some Remarks about the Flow over the Cylinder and the Spherep. 69
3.14 Surface Distribution of the Basic Solutionsp. 70
4 Small-Disturbance Flow over Three-Dimensional Wings: Formulation of the Problemp. 75
4.1 Definition of the Problemp. 75
4.2 The Boundary Condition on the Wingp. 76
4.3 Separation of the Thickness and the Lifting Problemsp. 78
4.4 Symmetric Wing with Nonzero Thickness at Zero Angle of Attackp. 79
4.5 Zero-Thickness Cambered Wing at Angle of Attack-Lifting Surfacesp. 82
4.6 The Aerodynamic Loadsp. 85
4.7 The Vortex Wakep. 88
4.8 Linearized Theory of Small-Disturbance Compressible Flowp. 90
5 Small-Disturbance Flow over Two-Dimensional Airfoilsp. 94
5.1 Symmetric Airfoil with Nonzero Thickness at Zero Angle of Attackp. 94
5.2 Zero-Thickness Airfoil at Angle of Attackp. 100
5.3 Classical Solution of the Lifting Problemp. 104
5.4 Aerodynamic Forces and Moments on a Thin Airfoilp. 106
5.5 The Lumped-Vortex Elementp. 114
5.6 Summary and Conclusions from Thin Airfoil Theoryp. 120
6 Exact Solutions with Complex Variablesp. 122
6.1 Summary of Complex Variable Theoryp. 122
6.2 The Complex Potentialp. 125
6.3 Simple Examplesp. 126
6.3.1 Uniform Stream and Singular Solutionsp. 126
6.3.2 Flow in a Cornerp. 127
6.4 Blasius Formula, Kutta-Joukowski Theoremp. 128
6.5 Conformal Mapping and the Joukowski Transformationp. 128
6.5.1 Flat Plate Airfoilp. 130
6.5.2 Leading-Edge Suctionp. 131
6.5.3 Flow Normal to a Flat Platep. 133
6.5.4 Circular Arc Airfoilp. 134
6.5.5 Symmetric Joukowski Airfoilp. 135
6.6 Airfoil with Finite Trailing-Edge Anglep. 137
6.7 Summary of Pressure Distributions for Exact Airfoil Solutionsp. 138
6.8 Method of Imagesp. 141
6.9 Generalized Kutta-Joukowski Theoremp. 146
7 Perturbation Methodsp. 151
7.1 Thin-Airfoil Problemp. 151
7.2 Second-Order Solutionp. 154
7.3 Leading-Edge Solutionp. 157
7.4 Matched Asymptotic Expansionsp. 160
7.5 Thin Airfoil between Wind Tunnel Wallsp. 163
8 Three-Dimensional Small-Disturbance Solutionsp. 167
8.1 Finite Wing: The Lifting Line Modelp. 167
8.1.1 Definition of the Problemp. 167
8.1.2 The Lifting-Line Modelp. 168
8.1.3 The Aerodynamic Loadsp. 172
8.1.4 The Elliptic Lift Distributionp. 173
8.1.5 General Spanwise Circulation Distributionp. 178
8.1.6 Twisted Elliptic Wingp. 181
8.1.7 Conclusions from Lifting-Line Theoryp. 183
8.2 Slender Wing Theoryp. 184
8.2.1 Definition of the Problemp. 184
8.2.2 Solution of the Flow over Slender Pointed Wingsp. 186
8.2.3 The Method of R. T. Jonesp. 192
8.2.4 Conclusions from Slender Wing Theoryp. 194
8.3 Slender Body Theoryp. 195
8.3.1 Axisymmetric Longitudinal Flow Past a Slender Body of Revolutionp. 196
8.3.2 Transverse Flow Past a Slender Body of Revolutionp. 198
8.3.3 Pressure and Force Informationp. 199
8.3.4 Conclusions from Slender Body Theoryp. 201
8.4 Far Field Calculation of Induced Dragp. 201
9 Numerical (Panel) Methodsp. 206
9.1 Basic Formulationp. 206
9.2 The Boundary Conditionsp. 207
9.3 Physical Considerationsp. 209
9.4 Reduction of the Problem to a Set of Linear Algebraic Equationsp. 213
9.5 Aerodynamic Loadsp. 216
9.6 Preliminary Considerations, Prior to Establishing Numerical Solutionsp. 217
9.7 Steps toward Constructing a Numerical Solutionp. 220
9.8 Example: Solution of Thin Airfoil with the Lumped-Vortex Elementp. 222
9.9 Accounting for Effects of Compressibility and Viscosityp. 226
10 Singularity Elements and Influence Coefficientsp. 230
10.1 Two-Dimensional Point Singularity Elementsp. 230
10.1.1 Two-Dimensional Point Sourcep. 230
10.1.2 Two-Dimensional Point Doubletp. 231
10.1.3 Two-Dimensional Point Vortexp. 231
10.2 Two-Dimensional Constant-Strength Singularity Elementsp. 232
10.2.1 Constant-Strength Source Distributionp. 233
10.2.2 Constant-Strength Doublet Distributionp. 235
10.2.3 Constant-Strength Vortex Distributionp. 236
10.3 Two-Dimensional Linear-Strength Singularity Elementsp. 237
10.3.1 Linear Source Distributionp. 238
10.3.2 Linear Doublet Distributionp. 239
10.3.3 Linear Vortex Distributionp. 241
10.3.4 Quadratic Doublet Distributionp. 242
10.4 Three-Dimensional Constant-Strength Singularity Elementsp. 244
10.4.1 Quadrilateral Sourcep. 245
10.4.2 Quadrilateral Doubletp. 247
10.4.3 Constant Doublet Panel Equivalence to Vortex Ringp. 250
10.4.4 Comparison of Near and Far Field Formulasp. 251
10.4.5 Constant-Strength Vortex Line Segmentp. 251
10.4.6 Vortex Ringp. 255
10.4.7 Horseshoe Vortexp. 256
10.5 Three-Dimensional Higher Order Elementsp. 258
11 Two-Dimensional Numerical Solutionsp. 262
11.1 Point Singularity Solutionsp. 262
11.1.1 Discrete Vortex Methodp. 263
11.1.2 Discrete Source Methodp. 272
11.2 Constant-Strength Singularity Solutions (Using the Neumann B.C.)p. 276
11.2.1 Constant Strength Source Methodp. 276
11.2.2 Constant-Strength Doublet Methodp. 280
11.2.3 Constant-Strength Vortex Methodp. 284
11.3 Constant-Potential (Dirichlet Boundary Condition) Methodsp. 288
11.3.1 Combined Source and Doublet Methodp. 290
11.3.2 Constant-Strength Doublet Methodp. 294
11.4 Linearly Varying Singularity Strength Methods (Using the Neumann B.C.)p. 298
11.4.1 Linear-Strength Source Methodp. 299
11.4.2 Linear-Strength Vortex Methodp. 303
11.5 Linearly Varying Singularity Strength Methods (Using the Dirichlet B.C.)p. 306
11.5.1 Linear Source/Doublet Methodp. 306
11.5.2 Linear Doublet Methodp. 312
11.6 Methods Based on Quadratic Doublet Distribution (Using the Dirichlet B.C.)p. 315
11.6.1 Linear Source/Quadratic Doublet Methodp. 315
11.6.2 Quadratic Doublet Methodp. 320
11.7 Some Conclusions about Panel Methodsp. 323
12 Three-Dimensional Numerical Solutionsp. 331
12.1 Lifting-Line Solution by Horseshoe Elementsp. 331
12.2 Modeling of Symmetry and Reflections from Solid Boundariesp. 338
12.3 Lifting-Surface Solution by Vortex Ring Elementsp. 340
12.4 Introduction to Panel Codes: A Brief Historyp. 351
12.5 First-Order Potential-Based Panel Methodsp. 353
12.6 Higher Order Panel Methodsp. 358
12.7 Sample Solutions with Panel Codesp. 360
13 Unsteady Incompressible Potential Flowp. 369
13.1 Formulation of the Problem and Choice of Coordinatesp. 369
13.2 Method of Solutionp. 373
13.3 Additional Physical Considerationsp. 375
13.4 Computation of Pressuresp. 376
13.5 Examples for the Unsteady Boundary Conditionp. 377
13.6 Summary of Solution Methodologyp. 380
13.7 Sudden Acceleration of a Flat Platep. 381
13.7.1 The Added Massp. 385
13.8 Unsteady Motion of a Two-Dimensional Thin Airfoilp. 387
13.8.1 Kinematicsp. 388
13.8.2 Wake Modelp. 389
13.8.3 Solution by the Time-Stepping Methodp. 391
13.8.4 Fluid Dynamic Loadsp. 394
13.9 Unsteady Motion of a Slender Wingp. 400
13.9.1 Kinematicsp. 401
13.9.2 Solution of the Flow over the Unsteady Slender Wingp. 401
13.10 Algorithm for Unsteady Airfoil Using the Lumped-Vortex Elementp. 407
13.11 Some Remarks about the Unsteady Kutta Conditionp. 416
13.12 Unsteady Lifting-Surface Solution by Vortex Ring Elementsp. 419
13.13 Unsteady Panel Methodsp. 433
14 The Laminar Boundary Layerp. 448
14.1 The Concept of the Boundary Layerp. 448
14.2 Boundary Layer on a Curved Surfacep. 452
14.3 Similar Solutions to the Boundary Layer Equationsp. 457
14.4 The von Karman Integral Momentum Equationp. 463
14.5 Solutions Using the von Karman Integral Equationp. 467
14.5.1 Approximate Polynomial Solutionp. 468
14.5.2 The Correlation Method of Thwaitesp. 469
14.6 Weak Interactions, the Goldstein Singularity, and Wakesp. 471
14.7 Two-Equation Integral Boundary Layer Methodp. 473
14.8 Viscous-Inviscid Interaction Methodp. 475
14.9 Concluding Example: The Flow over a Symmetric Airfoilp. 479
15 Enhancement of the Potential Flow Modelp. 483
15.1 Wake Rollupp. 483
15.2 Coupling between Potential Flow and Boundary Layer Solversp. 487
15.2.1 The Laminar/Turbulent Boundary Layer and Transitionp. 487
15.2.2 Viscous-Inviscid Coupling, Including Turbulent Boundary Layerp. 491
15.3 Influence of Viscous Flow Effects on Airfoil Designp. 495
15.3.1 Low Drag Considerationsp. 498
15.3.2 High Lift Considerationsp. 499
15.4 Flow over Wings at High Angles of Attackp. 505
15.4.1 Flow Separation on Wings with Unswept Leading Edge - Experimental Observationsp. 508
15.4.2 Flow Separation on Wings with Unswept Leading Edge - Modelingp. 510
15.4.3 Flow Separation on Wings with Highly Swept Leading Edge - Experimental Observationsp. 516
15.4.4 Modeling of Highly Swept Leading-Edge Separationp. 523
15.5 Possible Additional Features of Panel Codesp. 528
A Airfoil Integralsp. 537
B Singularity Distribution Integralsp. 540
C Principal Value of the Lifting Surface Integral I[subscript L]p. 545