Unsteady Aerodynamics: Potential and Vortex Methods

ISBN-13: 9781119762478 / Angielski / Twarda / 2023 / 576 str.

Belgium) Grigorios Dimitriadis (University of Liège

Opis

Unsteady Aerodynamics A comprehensive overview of unsteady aerodynamics and its applications The study of unsteady aerodynamics goes back a century and has only become more significant as aircraft become increasingly sophisticated, fly faster, and their structures are lighter and more flexible. Progress in the understanding of flow physics, computing power and techniques, and modelling technologies has led to corresponding progress in unsteady aerodynamics, with a wide range of methods currently used to predict the performance of engineering structures under unsteady conditions. Unsteady Aerodynamics offers a comprehensive and systematic overview of the application of potential and vortex methods to the subject. Beginning with an introduction to the fundamentals of unsteady flow, it then discusses the modelling of attached and separated, incompressible and compressible flows around two-dimensional and three-dimensional bodies. The result is an essential resource for design and simulation in aerospace engineering. Unsteady Aerodynamics readers will also find: MATLAB examples and exercises throughout, with codes and solutions on an accompanying website Detailed discussion of most classes of unsteady phenomena, including flapping flight, transonic flow, dynamic stall, flow around bluff bodies and more Validation of theoretical and numerical predictions using comparisons to experimental data from the literature Unsteady Aerodynamics is ideal for researchers, engineers, and advanced students in aerospace engineering.

Spis treści

Preface vii1 Introduction 11.1 Why potential and vortex methods? 21.2 Outline of this book 3References 42 Unsteady flow fundamentals 52.1 Introduction 52.2 From Navier-Stokes to unsteady incompressible potential flow 52.2.1 Irrotational flow 62.2.2 Laplace's and Bernoulli's equations 72.2.3 Motion in an incompressible, inviscid, irrotational fluid 92.3 Incompressible potential flow solutions 152.3.1 Green's third identity 222.3.2 Solutions in two dimensions 432.4 From Navier-Stokes to unsteady compressible potential flow 442.4.1 The compressible Bernoulli equation 452.4.2 The full potential equation 462.4.3 The transonic small disturbance equation 482.4.4 The linearized small disturbance equation 492.4.5 The compressible unsteady pressure coefficient 512.4.6 Motion in a compressible, inviscid, irrotational fluid 542.5 Subsonic linearised potential flow solutions 562.6 Supersonic linearised potential flow solutions 632.7 Vorticity and circulation 692.7.1 Solutions of the vorticity transport equations 732.7.2 Vorticity-Moment and Kutta-Joukowski Theorems 782.7.3 The wake and the Kutta condition 802.8 Concluding Remarks 82References 833 Analytical incompressible 2D models 853.1 Introduction 853.2 Steady thin airfoil theory 853.3 Fundamentals of Wagner and Theodorsen theory 963.3.1 Flow induced by the source distribution 1003.3.2 Flow induced by the vortex distribution 1053.3.3 Imposing the impermeability boundary condition 1083.3.4 Calculating the loads due to the source distribution 1123.3.5 Imposing the Kutta condition 1143.4 Wagner Theory 1173.4.1 TheWagner function 1233.4.2 Drag and thrust 1273.4.3 General motion 1343.4.4 Total loads 1363.4.5 Quasi-steady aerodynamics 1433.5 Theodorsen Theory 1453.5.1 Theodorsen's function 1483.5.2 Total loads for sinusoidal motion 1523.5.3 General motion 1593.6 Finite state theory 1643.6.1 Glauert expansions 1683.6.2 Solution of the impermeability equation 1783.6.3 Completing the equations 1803.6.4 Kutta condition and aerodynamic loads 1833.7 Concluding Remarks 1923.8 Exercises 193References 1934 Numerical incompressible 2D models 1954.1 Introduction 1954.2 Lumped vortex method 1954.2.1 Unsteady flows 2054.2.2 Free wakes 2154.3 Gust encounters 2214.3.1 Pitching and plunging wings 2254.4 Frequency domain formulation of the lumped vortex method 2374.5 Source and vortex panel method 2434.5.1 Impulsively started flow 2574.5.2 Thrust and propulsive efficiency 2664.6 Theodorsen's function and wake shape 2714.7 Steady and unsteady Kutta conditions 2734.7.1 The unsteady Kutta condition 2804.8 Concluding Remarks 2884.9 Exercises 288References 2885 Finite wings 2915.1 Introduction 2915.1.1 Rigid wings and flexible wings 2925.2 Finite wings in steady flow 2935.3 The impulsively started elliptical wing 3025.3.1 The solution by Jones 3025.3.2 Unsteady lifting line solution 3145.4 The unsteady vortex lattice method 3195.4.1 Impulsive start of an elliptical wing 3335.4.2 Other planforms 3405.5 Rigid harmonic motion 3435.5.1 Longitudinal harmonic motion 3445.5.2 Frequency domain load calculations 3505.5.3 Lateral harmonic motion 3565.5.4 Aerodynamic stability derivatives 3605.6 The 3D source and doublet panel method 3665.7 Flexible motion 3815.7.1 Source and doublet panel method in the frequency domain 3905.8 Concluding Remarks 3965.9 Exercises 397References 3976 Unsteady compressible flow 3996.1 Introduction 3996.2 Steady subsonic potential flow 3996.3 Unsteady subsonic potential flow 4066.3.1 The Doublet Lattice Method 4076.3.2 Unsteady 3D subsonic source and doublet panel method 4196.3.3 Steady correction of the Doublet Lattice Method 4326.3.4 Unsteady 2D subsonic source and doublet panel method 4356.4 Unsteady supersonic potential flow 4376.4.1 The Mach box method 4386.4.2 The Mach panel method 4476.5 Transonic flow 4536.5.1 Steady transonic flow 4546.5.2 Time linearized transonic small perturbation equation 4606.5.3 Unsteady transonic correction methods 4636.6 Concluding Remarks 4746.7 Exercises 475References 4757 Viscous flow 4777.1 Introduction 4777.1.1 Steady flow separation mechanisms 4797.1.2 Dynamic stall 4847.2 Impulsively started flow around a 2D flat plate at high angles of attack 4907.2.1 Flow separation criteria 4987.3 Flow around a 2D circular cylinder 5047.3.1 The Discrete Vortex Method for bluff bodies 5077.3.2 Modelling the flow past a circular cylinder using the DVM 5107.4 Flow past 2D rectangular cylinders 5217.4.1 Modelling the flow past rectangular cylinders using the DVM 5227.5 Concluding Remarks 5277.6 Exercises 527References 527A Fundamental solutions of Laplace's equation 529A.1 The 2D point source 529A.2 The 2D point vortex 531A.3 The source line panel 533A.4 The vortex line panel 537A.5 The horseshoe vortex 539A.6 The vortex line segment 542A.7 The vortex ring 543A.8 The 3D point source 545A.9 The 3D point doublet 547A.10 The source surface panel 548A.11 The doublet surface panel 554References 558B Fundamental solutions of the linearized small disturbance equation 559B.1 The subsonic doublet surface panel 559B.2 The acoustic source surface panel 561B.3 The acoustic doublet surface panel 562B.4 The supersonic source surface panel 563References 568C Wagner's derivation of the Kutta condition 569References 570

O autorze

Grigorios Dimitriadis, PhD, is Professor of Fluid Structure Interaction and Experimental Aerodynamics in the Aerospace and Mechanical Engineering Department, University of Liège, Belgium and Adjunct Professor in Aeroelasticity at the von Karman Institute for Fluid Dynamics, Belgium. He has published extensively on unsteady aerodynamics and related fields.