Experimental Aerodynamics: An Introductory Guide

Description

This book presents experimental techniques in the field of aerodynamics, a discipline that is essential in numerous areas, such as the design of aerial and ground vehicles and engines, the production of energy, and understanding the wind resistance of buildings. Aerodynamics is not only concerned with improving the performance and comfort of vehicles, but also with reducing their environmental impact. The book provides updated information on the experimental and technical methods used by aerodynamicists, engineers and researchers. It describes the various types of wind tunnels – from subsonic to hypersonic – as well as the problems posed by their design and operation. The book also focuses on metrology, which has allowed us to gain a detailed understanding of the local properties of flows, and examines current developments toward creating a methodology combining experiments and numerical simulations: the computer-assisted wind tunnel. Lastly, it offers an overview of experimental aerodynamics based on a prospective vision of the discipline, and discusses potential futures challenges. The book can be used as a textbook for graduate courses in aerodynamics, typically offered to students of aerospace and mechanical engineering programs, and as a learning tool for professionals and engineers in the fields of aerodynamics, aeronautics and astronautics automobile. Foreword Preface Acknowledgements Contents About the Authors Acronyms 1 The Experimental Approach in Aerodynamic Design 1.1 Aerodynamics, What for? 1.2 Review of the Theory 1.3 Limitations and Constraints of Numerical Methods 1.4 Some Constraints for Wind Tunnel Test 1.5 Deformation of Models 1.6 Industrial Aerodynamics Testing: Combining Tests and Numerical Simulation 1.7 Flight Tests 1.7.1 Flight Test Beds 1.7.2 Catapulted Flight Test 1.7.3 Aeroballistics Flight Test 1.8 Simulated Altitude Test Cells 1.8.1 Impact of Altitude 1.8.2 How Does an Altitude Test Cell Work? 1.8.3 Benefits of Simulated Altitude Tests in Addition to Ground 2 Wind Tunnels and Other Aerodynamic Test Facilities 2.1 Background of Wind Tunnels 2.1.1 Wind Tunnel Principle 2.1.2 The Eiffel Type or Open Circuit Wind Tunnel 2.1.3 The Prandtl Type or Closed Circuit Wind Tunnel 2.2 From Wind Tunnel Test to Reality 2.3 Reynolds Number Effect and Laminar to Turbulent Transition 2.4 Dynamics Similarity and Dimensionless Parameters 2.5 Constraints of Testing in a Wind Tunnel 2.5.1 Effects of Blockage in the Test Section 2.5.2 Model Installation and Different Kinds of Support 2.5.3 Freestream Vortical and Acoustic Perturbations 2.6 The Main Sections of a Wind Tunnel 2.7 Design and Manufacturing of Wind Tunnel Models 3 Subsonic Wind Tunnels 3.1 Subsonic Wind Tunnels for Aeronautics 3.1.1 Historical Subsonic Wind Tunnels in France 3.1.2 Circular to Octagonal Cross Section Wind Tunnel 3.1.3 Low Reynolds Number Wind Tunnel 3.1.4 Multiple Test Section Wind Tunnel 3.1.5 Low Turbulence Research Wind Tunnel 3.1.6 Pressurised Subsonic Wind Tunnel 3.1.7 Large Research Wind Tunnels 3.2 Special Purpose Wind Tunnels 3.2.1 Vertical Wind Tunnel 3.2.2 Climatic Wind Tunnels 3.2.3 Icing Wind Tunnel 3.2.4 Anechoic Chambers and Aeroacoustic Wind Tunnels 3.2.5 Dual Purpose Aerodynamic and Acoustic Wind Tunnel 3.3 Wind Tunnels for Ground Vehicles 3.3.1 Specifications 3.3.2 Long Test Section Wind Tunnel 3.3.3 Wind Tunnels for Full Scale Automobile 3.4 Water Tunnels 3.4.1 General Description 3.4.2 Low Speed Water Tunnel 3.4.3 Hydrodynamic Channel for Polarographic Measurements 4 Transonic Wind Tunnels 4.1 Definition of the Transonic Regime 4.2 Blockage Reduction and Flow Un-Chocking 4.2.1 Perforated or Slotted Walls 4.2.2 Adaptive Walls 4.2.3 Reflection of Disturbances 4.2.4 Double Throat Diffuser 4.3 Typical Transonic Wind Tunnels 4.3.1 Very Large Transonic Wind Tunnel 4.3.2 Transonic Wind Tunnel for Research 4.3.3 Transonic-Supersonic Wind Tunnel 4.3.4 A Cryogenic and Pressurised Wind Tunnel: The European Transonic Wind Tunnel 5 Supersonic Wind Tunnels 5.1 Convergent-Divergent Nozzle 5.2 Defining of the Contour of a Supersonic Nozzle 5.3 Typical Supersonic Wind Tunnels 5.3.1 Basic Research Supersonic Wind Tunnel 5.3.2 Low Turbulence Supersonic Wind Tunnel 5.3.3 Transonic/Supersonic Open Jet Facilities 5.3.4 Large Variable Mach Number Wind Tunnel 5.3.5 Blow Down Transonic/Supersonic Wind Tunnel 5.4 Mach 6 Quiet Wind Tunnel 6 Hypersonic Wind Tunnels 6.1 Types of Hypersonic Wind Tunnels 6.2 Hypersonic “Cold” Wind Tunnels 6.3 Hypersonic “Hot” or Hyper-enthalpic Wind Tunnels 6.3.1 Hot Shot Wind Tunnels 6.3.2 Shock Tubes and Shock Tunnels 6.3.3 High Enthalpy Shock Tunnel 6.3.4 Plasma Wind Tunnels 6.3.5 Continuous Plasma Wind Tunnel 6.3.6 Other Plasma Type Facilities 7 Flow Visualisation Techniques 7.1 Earlier Contribution to Visualisation Techniques 7.2 Surface Flow Visualisations 7.2.1 Surface Oil Flow Visualisation 7.2.2 Visualisation by Sublimating Product 7.3 Visualisation in Water Tunnels 7.4 Laser Tomoscopy or Laser Sheet Visualisation 7.5 Visualisation by Optical Imaging 7.5.1 Schlieren and Shadowgraph Techniques 7.5.2 Interferometry 7.5.3 Differential Interferometry 7.6 Short Exposure Time Visualisation 7.7 Visualisation by Induced Light Emission 7.7.1 Glow Discharge Method 7.7.2 Electron Beam-Induced Fluorescence (EBF) 8 Measurement of Aerodynamic Forces and Moments 8.1 The Aerodynamic Forces and Moments 8.2 Aerodynamic Balances 8.2.1 Forces and Strain Gauges 8.2.2 Sting Type Force Balance 8.2.3 Force Balance by Direct Force Measurements 8.2.4 Balance for Ground Vehicle 8.3 Drag Determination from Wake Survey 9 Characterisation of Flow Properties at the Surface 9.1 The Action of a Fluid at the Wall 9.2 Measurement of Pressure at the Wall 9.2.1 Pressure Scanning Systems 9.2.2 Types of Pressure Transducers 9.2.3 Sensitivity and Response Time 9.3 Pressure Sensitive Paint 9.3.1 Principle and Composition of the Pressure Sensitive Paint 9.3.2 Relation Between the Pressure and the Luminous Intensity 9.3.3 Main Areas of Application of the PSP 9.3.4 Developments in the Field of PSP 9.4 Skin Friction Measurement 9.4.1 Floating Element Balance 9.4.2 Hot Film Surface Gauge 9.4.3 Stanton and Preston Tubes 9.4.4 Oil Film Interferometry 9.4.5 Liquid Crystals Thermography 9.4.6 Adjustment Based on the Logarithmic Law of Turbulent Boundary Layers 9.5 Measurement of the Wall Heat Transfer 9.5.1 Calorimetric Techniques 9.5.2 Thermo-Sensitive Paints 9.5.3 Infrared Thermography 9.6 Measurement of Deformations of the Models 10 Intrusive Measurement Techniques 10.1 Solid Probes: Benefits and Limitations 10.2 Pressure Probes 10.2.1 Measurement of Stagnation or Total Pressure, Pitot Probe 10.2.2 Measurement Using Pitot-Static or Prandtl Probe 10.2.3 Multi-holes Probe to Resolve the Direction of the Velocity Vector 10.3 Temperature Probes 10.4 Measurement Using Hot Wire and Hot Film Anemometry 10.4.1 Basic Principles 10.4.2 Modes of Hot-Wire Anemometry 10.4.3 Types of Hot Wire Probes 10.4.4 Applications 11 Non-intrusive Measurement Techniques 11.1 Basic Principle of Non-intrusive Techniques 11.2 Interferometry 11.2.1 Light Interference and Refractive Index 11.2.2 Mach-Zehnder Interferometry 11.2.3 Holographic Interferometry 11.3 Mechanism of Light Scattering 11.4 Laser Doppler Velocimetry or Anemometry 11.4.1 Basic Principles 11.4.2 Signal Analysis 11.4.3 Modes of Operation 11.4.4 Multi-components Measurements 11.4.5 Flow Seeding 11.5 Doppler Global Velocimetry 11.6 Particle Image Velocimetry 11.6.1 Basic Principle of Planar PIV 11.6.2 Image Processing 11.6.3 Three Components Stereo PIV 11.6.4 PIV Tomography or PIV 3D 11.6.5 Particle Tracking Velocimetry 11.6.6 Time Resolved Particle Image Velocimetry 11.6.7 PIV Vs. LDV: A Brief Conclusion 12 Laser Spectroscopy and Electron Beam Excitation 12.1 Basic Principles 12.2 Laser Absorption Spectroscopy 12.3 Rayleigh Scattering 12.4 Raman Scattering 12.5 Stimulated Raman Scattering 12.6 Laser-Induced Fluorescence (LIF) 12.7 Electron Beam-Induced Fluorescence (EBF) 12.8 Electron Beam Induced Glow Discharge Measurements 12.9 Detection of X-ray Emission by Electron Beam Excitation 13 Computer-Aided Wind Tunnel Test and Analysis 13.1 Experimental Versus Numerical Analysis 13.2 CFD for the Preparation of Wind Tunnel Tests 13.3 Correction and Monitoring of Wind Tunnel Results by CFD 13.4 Towards the Hybrid Wind Tunnel 13.5 Reconstruction of Data 14 Prospects and Challenges for Aerodynamics 14.1 Role of the Wind Tunnel in Design and Optimisation 14.2 Flow Control 14.3 Developments in Aeroacoustic Measurements 14.4 Search for Novel Aircraft Architectures 14.5 Supersonic and Hypersonic Flights 14.6 Prospects for the Aerodynamic Design 14.7 Aerodynamics and Teaching Bibliography