Principles of helicopter aerodynamics /

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Bibliographic Details
Author / Creator:	Leishman, J. Gordon.
Edition:	1st pbk. ed.
Imprint:	Cambridge ; New York : Cambridge University Press, 2002.
Description:	xxxix, 496 p. : ill. ; 26 cm.
Language:	English
Series:	Cambridge aerospace series ; 12
Subject:	Helicopters -- Aerodynamics. Helicopters -- Aerodynamics.
Format:	Print Book
URL for this record:	http://pi.lib.uchicago.edu/1001/cat/bib/7794871

Hidden Bibliographic Details
ISBN:	0521523966 9780521523967
Notes:	Originally published: 2000. Includes bibliographical references and and index.

Table of Contents:

Preface to the Second Edition
Preface to the First Edition
Acknowledgments
List of Main Symbols
1. Introduction: A History of Helicopter Flight
1.1. Rising Vertically
1.2. Producing Thrust
1.3. Key Technical Problems in Attaining Vertical Flight
1.4. Early Thinking
1.5. The Hoppers
1.6. The First Hoverers
1.7. Not Quite a Helicopter
1.8. Engines: A Key Enabling Technology
1.9. On the Verge of Success
1.10. The First Successes
1.11. Toward Mass Production
1.12. Maturing Technology
1.13. Compounds, Tilt-Wings, and Tilt-Rotors
1.14. Chapter Review
1.15. Questions
Bibliography
2. Fundamentals of Rotor Aerodynamics
2.1. Introduction
2.2. Momentum Theory Analysis in Hovering Flight
2.2.1. Flow Near a Hovering Rotor
2.2.2. Conservation Laws of Aerodynamics
2.2.3. Application to a Hovering Rotor
2.3. Disk Loading and Power Loading
2.4. Induced Inflow Ratio
2.5. Thrust and Power Coefficients
2.6. Comparison of Theory with Measured Rotor Performance
2.7. Nonideal Effects on Rotor Performance
2.8. Figure of Merit
2.9. Estimating Nonideal Effects from Rotor Measurements
2.10. Induced Tip Loss
2.11. Rotor Solidity and Blade Loading Coefficient
2.12. Power Loading
2.13. Momentum Analysis in Axial Climb and Descent
2.13.1. Axial Climb
2.13.2. Axial Descent
2.13.3. Region between Hover and Windmill State
2.13.4. Power Required in Axial Climbing and Descending Flight
2.13.5. Four Working States of the Rotor in Axial Flight
2.13.6. Vortex Ring State
2.13.7. Autorotation
2.14. Momentum Analysis in Forward Flight
2.14.1. Induced Velocity in Forward Flight
2.14.2. Special Case, [alpha] = 0
2.14.3. Numerical Solution to Inflow Equation
2.14.4. General Form of the Inflow Equation
2.14.5. Validity of the Inflow Equation
2.14.6. Rotor Power Requirements in Forward Flight
2.15. Other Applications of the Momentum Theory
2.15.1. Coaxial Rotor Systems
2.15.2. Tandem Rotor Systems
2.16. Chapter Review
2.17. Questions
Bibliography
3. Blade Element Analysis
3.1. Introduction
3.2. Blade Element Analysis in Hover and Axial Flight
3.2.1. Integrated Rotor Thrust and Power
3.2.2. Thrust Approximations
3.2.3. Torque-Power Approximations
3.2.4. Tip-Loss Factor
3.3. Blade Element Momentum Theory (BEMT)
3.3.1. Assumed Radial Distributions of Inflow on the Blades
3.3.2. Radial Inflow Equation
3.3.3. Ideal Twist
3.3.4. BEMT: Numerical Solution
3.3.5. Distributions of Inflow and Airloads
3.3.6. Effects of Swirl Velocity
3.3.7. The Optimum Hovering Rotor
3.3.8. Circulation Theory of Lift
3.3.9. Power Estimates for the Rotor
3.3.10. Prandtl's Tip-Loss Function
3.3.11. Blade Design and Figure of Merit
3.3.12. BEMT in Climbing Flight
3.3.13. Further Comparisons of BEMT with Experiment
3.3.14. Compressibility Corrections to Rotor Performance
3.4. Equivalent Blade Chords and Weighted Solidity
3.4.1. Mean Wing Chords
3.4.2. Thrust Weighted Solidity
3.4.3. Power-Torque Weighted Solidity
3.4.4. Weighted Solidity of the Optimum Rotor
3.4.5. Weighted Solidities of Tapered Blades
3.4.6. Mean Lift Coefficient
3.5. Blade Element Analysis in Forward Flight
3.5.1. Determining Blade Forces
3.5.2. Definition of the Approximate Induced Velocity Field
3.6. Chapter Review
3.7. Questions
Bibliography
4. Rotating Blade Motion
4.1. Introduction
4.2. Types of Rotors
4.3. Equilibrium about the Flapping Hinge
4.4. Equilibrium about the Lead-Lag Hinge
4.5. Equation of Motion for a Flapping Blade
4.6. Physical Description of Blade Flapping
4.6.1. Coning Angle
4.6.2. Longitudinal Flapping Angle
4.6.3. Lateral Flapping Angle
4.6.4. Higher Harmonics of Blade Flapping
4.7. Dynamics of Blade Flapping with a Hinge Offset
4.8. Blade Feathering and the Swashplate
4.9. Review of Rotor Reference Axes
4.10. Dynamics of a Lagging Blade with a Hinge Offset
4.11. Coupled Flap-Lag Motion
4.12. Coupled Pitch-Flap Motion
4.13. Other Types of Rotors
4.13.1. Teetering Rotor
4.13.2. Semi-Rigid or Hingeless Rotors
4.14. Introduction to Rotor Trim
4.14.1. Equations for Free-Flight Trim
4.14.2. Typical Trim Solution Procedure for Level Flight
4.15. Chapter Review
4.16. Questions
Bibliography
5. Helicopter Performance
5.1. Introduction
5.2. The International Standard Atmosphere
5.3. Hovering and Axial Climb Performance
5.4. Forward Flight Performance
5.4.1. Induced Power
5.4.2. Blade Profile Power
5.4.3. Compressibility Losses and Tip Relief
5.4.4. Reverse Flow
5.4.5. Parasitic Power
5.4.6. Climb Power
5.4.7. Tail Rotor Power
5.4.8. Total Power
5.5. Performance Analysis
5.5.1. Effect of Gross Weight
5.5.2. Effect of Density Altitude
5.5.3. Life-to-Drag Ratios
5.5.4. Climb Performance
5.5.5. Engine Fuel Consumption
5.5.6. Speed for Minimum Power
5.5.7. Speed for Maximum Range
5.5.8. Range-Payload and Endurance-Payload Relations
5.5.9. Maximum Altitude or Ceiling
5.5.10. Factors Affecting Maximum Attainable Forward Speed
5.5.11. Performance of Coaxial and Tandem Dual Rotor Systems
5.6. Autorotational Performance
5.6.1. Autorotation in Forward Flight
5.6.2. Height-Velocity (H-V) Curve
5.6.3. Autorotation Index
5.7. Vortex Ring State (VRS)
5.7.1. Quantification of VRS Effects
5.7.2. Implications of VRS on Flight Boundary
5.8. Ground Effect
5.8.1. Hovering Flight Near the Ground
5.8.2. Forward Flight Near the Ground
5.9. Performance in Maneuvering Flight
5.9.1. Steady Maneuvers
5.9.2. Transient Maneuvers
5.10. Factors Influencing Performance Degradation
5.11. Chapter Review
5.12. Questions
Bibliography
6. Aerodynamic Design of Helicopters
6.1. Introduction
6.2. Overall Design Requirements
6.3. Conceptual and Preliminary Design Processes
6.4. Design of the Main Rotor
6.4.1. Rotor Diameter
6.4.2. Tip Speed
6.4.3. Rotor Solidity
6.4.4. Number of Blades
6.4.5. Blade Twist
6.4.6. Blade Planform and Tip Shape
6.4.7. Airfoil Sections
6.5. Case Study: The BERP Rotor
6.6. Fuselage Aerodynamic Design Issues
6.6.1. Fuselage Drag
6.6.2. Vertical Drag and Download Penalty
6.6.3. Vertical Drag Recovery
6.6.4. Fuselage Side-Force
6.7. Empennage Design
6.7.1. Horizontal Stabilizer
6.7.2. Vertical Stabilizer
6.8. Role of Wind Tunnels in Aerodynamic Design
6.9. Design of Tail Rotors
6.9.1. Physical Size
6.9.2. Thrust Requirements
6.9.3. Precessional Stall Issues
6.9.4. "Pushers" versus "Tractors"
6.9.5. Design Requirements
6.9.6. Representative Tail Rotor Designs
6.10. Other Anti-Torque Devices
6.10.1. Fan-in-Fin
6.10.2. NOTAR Design
6.11. High-Speed Rotorcraft
6.11.1. Compound Helicopters
6.11.2. Tilt-Rotors
6.11.3. Other High-Speed Concepts
6.12. Smart Rotor Systems
6.13. Human-Powered Helicopter
6.14. Hovering Micro Air Vehicles
6.15. Chapter Review
6.16. Questions
Bibliography
7. Aerodynamics of Rotor Airfoils
7.1. Introduction
7.2. Helicopter Rotor Airfoil Requirements
7.3. Reynolds Number and Mach Number Effects
7.3.1. Reynolds Number
7.3.2. Concept of the Boundary Layer
7.3.3. Mach Number
7.3.4. Model Rotor Similarity Parameters
7.4. Airfoil Shape Definition
7.5. Airfoil Pressure Distributions
7.5.1. Pressure Coefficient
7.5.2. Critical Pressure Coefficient
7.5.3. Synthesis of Chordwise Pressure
7.5.4. Measurements of Chordwise Pressure
7.6. Aerodynamics of a Representative Airfoil Section
7.6.1. Integration of Distributed Forces
7.6.2. Pressure Integration
7.6.3. Representative Force and Moment Results
7.7. Pitching Moment and Related Issues
7.7.1. Aerodynamic Center
7.7.2. Center of Pressure
7.7.3. Effect of Airfoil Shape on Pitching Moment
7.7.4. Use of Trailing Edge Tabs
7.7.5. Reflexed Airfoils
7.8. Drag
7.9. Maximum Lift and Stall Characteristics
7.9.1. Effects of Reynolds Number
7.9.2. Effects of Mach Number
7.10. Advanced Rotor Airfoil Design
7.11. Representing Static Airfoil Characteristics
7.11.1. Linear Aerodynamic Models
7.11.2. Nonlinear Aerodynamic Models
7.11.3. Table Look-Up
7.11.4. Direct Curve Fitting
7.11.5. Beddoes Method
7.11.6. High Angle of Attack Range
7.12. Circulation Controlled Airfoils
7.13. Very Low Reynolds Number Airfoil Characteristics
7.14. Effects of Damage on Airfoil Performance
7.15. Chapter Review
7.16. Questions
Bibliography
8. Unsteady Airfoil Behavior
8.1. Introduction
8.2. Sources of Unsteady Aerodynamic Loading
8.3. Concepts of the Blade Wake
8.4. Reduced Frequency and Reduced Time
8.5. Unsteady Attached Flow
8.6. Principles of Quasi-Steady Thin-Airfoil Theory
8.7. Theodorsen's Theory
8.7.1. Pure Angle of Attack Oscillations
8.7.2. Pure Plunging Oscillations
8.7.3. Pitching Oscillations
8.8. The Returning Wake: Loewy's Problem
8.9. Sinusoidal Gust: Sears's Problem
8.10. Indicial Response: Wagner's Problem
8.11. Sharp-Edged Gust: Kussner's Problem
8.12. Traveling Sharp-Edged Gust: Miles's Problem
8.13. Time-Varying Incident Velocity
8.14. General Application of the Indicial Response Method
8.14.1. Recurrence Solution to the Duhamel Integral
8.14.2. State-Space Solution for Arbitrary Motion
8.15. Indicial Method for Subsonic Compressible Flow
8.15.1. Approximations to the Indicial Response
8.15.2. Indicial Lift from Angle of Attack
8.15.3. Indicial Lift from Pitch Rate
8.15.4. Determination of Indicial Function Coefficients
8.15.5. Indicial Pitching Moment from Angle of Attack
8.15.6. Indicial Pitching Moment from Pitch Rate
8.15.7. Unsteady Axial Force and Airfoil Drag
8.15.8. State-Space Aerodynamic Model for Compressible Flow
8.15.9. Comparison with Experiment
8.16. Nonuniform Vertical Velocity Fields
8.16.1. Exact Subsonic Linear Theory
8.16.2. Approximations to the Sharp-Edged Gust Functions
8.16.3. Response to an Arbitrary Vertical Gust
8.16.4. Blade-Vortex Interaction (BVI) Problem
8.16.5. Convecting Vertical Gusts in Subsonic Flow
8.17. Time-Varying Incident Mach Number
8.18. Unsteady Aerodynamics of Flaps
8.18.1. Incompressible Flow Theory
8.18.2. Subsonic Flow Theory
8.18.3. Comparison with Measurements
8.19. Principles of Noise Produced by Unsteady Forces
8.19.1. Retarded Time and Source Time
8.19.2. Wave Tracing
8.19.3. Compactness
8.19.4. Trace or Phase Mach Number
8.19.5. Ffowcs-Williams-Hawkins Equation
8.19.6. BVI Acoustic Model Problem
8.19.7. Comparison of Aeroacoustic Methods
8.19.8. Methods of Rotor Noise Reduction
8.20. Chapter Review
8.21. Questions
Bibliography
9. Dynamic Stall
9.1. Introduction
9.2. Flow Morphology of Dynamic Stall
9.3. Dynamic Stall in the Rotor Environment
9.4. Effects of Forcing Conditions on Dynamic Stall
9.5. Modeling of Dynamic Stall
9.5.1. Semi-Empirical Models of Dynamic Stall
9.5.2. Capabilities of Dynamic Stall Modeling
9.5.3. Future Modeling Goals with Semi-Empirical Models
9.6. Torsional Damping
9.7. Effects of Sweep Angle on Dynamic Stall
9.8. Effect of Airfoil Shape on Dynamic Stall
9.9. Three-Dimensional Effects on Dynamic Stall
9.10. Time-Varying Velocity Effects on Dynamic Stall
9.11. Prediction of In-Flight Airloads
9.12. Stall Control
9.13. Chapter Review
9.14. Questions
Bibliography
10. Rotor Wakes and Blade Tip Vortices
10.1. Introduction
10.2. Flow Visualization Techniques
10.2.1. Natural Condensation Effects
10.2.2. Smoke Flow Visualization
10.2.3. Density Gradient Methods
10.3. Characteristics of the Rotor Wake in Hover
10.3.1. General Features
10.3.2. Wake Geometry in Hover
10.4. Characteristics of the Rotor Wake in Forward Flight
10.4.1. Wake Boundaries
10.4.2. Blade-Vortex Interactions (BVIs)
10.5. Other Characteristics of Rotor Wakes
10.5.1. Periodicity versus Aperiodicity
10.5.2. Vortex Perturbations and Instabilities
10.6. Detailed Structure of the Tip Vortices
10.6.1. Velocity Field
10.6.2. Models for the Tip Vortex
10.6.3. Vorticity Diffusion Effects and Vortex Core Growth
10.6.4. Correlation of Rotor Tip Vortex Data
10.6.5. Flow Rotation Effects on Turbulence Inside Vortices
10.7. Vortex Models of the Rotor Wake
10.7.1. Biot-Savart Law
10.7.2. Vortex Segmentation
10.7.3. Governing Equations for the Convecting Vortex Wake
10.7.4. Prescribed Wake Models for Hovering Flight
10.7.5. Prescribed Vortex Wake Models for Forward Flight
10.7.6. Free-Vortex Wake Analyses
10.8. Aperiodic Wake Developments
10.8.1. Wake Stability Analysis
10.8.2. Flow Visualization of Transient Wake Problems
10.8.3. Dynamic Inflow
10.8.4. Time-Marching Free-Vortex Wakes
10.8.5. Simulation of Carpenter & Friedovich Problem
10.9. General Dynamic Inflow Models
10.10. Descending Flight and the Vortex Ring State
10.11. Wake Developments in Maneuvering Flight
10.12. Chapter Review
10.13. Questions
Bibliography
11. Rotor-Airframe Interactional Aerodynamics
11.1. Introduction
11.2. Rotor-Fuselage Interactions
11.2.1. Effects of the Fuselage on Rotor Performance
11.2.2. Time-Averaged Effects on the Airframe
11.2.3. Unsteady Rotor-Fuselage Interactions
11.2.4. Fuselage Side-Forces
11.2.5. Modeling of Rotor-Fuselage Interactions
11.3. Rotor-Empennage Interactions
11.3.1. Airloads on the Horizontal Tail
11.3.2. Modeling of Rotor-Empennage Interactions
11.4. Rotor-Tail Rotor Interactions
11.5. Chapter Review
11.6. Questions
Bibliography
12. Autogiros and Gyroplanes
12.1. Introduction
12.2. The Curious Phenomenon of Autorotation
12.3. Review of Autorotational Physics
12.4. Rolling Rotors: The Dilemma of Asymmetric Lift
12.5. Innovation of the Flapping and Lagging Hinges
12.6. Prerotating the Rotor
12.7. Autogiro Theory Meets Practice
12.8. Vertical Flight Performance of the Autogiro
12.9. Forward Flight Performance of the Autogiro
12.10. Comparison of Autogiro Performance with the Helicopter
12.11. Airfoils for Autogiros
12.12. NACA Research on Autogiros
12.13. Giving Better Control: Orientable Rotors
12.14. Improving Performance: Jump and Towering Takeoffs
12.15. Ground and Air Resonance
12.16. Helicopters Eclipse Autogiros
12.17. Renaissance of the Autogiro?
12.18. Chapter Review
12.19. Questions
Bibliography
13. Aerodynamics of Wind Turbines
13.1. Introduction
13.2. History of Wind Turbine Development
13.3. Power in the Wind
13.4. Momentum Theory Analysis for a Wind Turbine
13.4.1. Power and Thrust Coefficients for a Wind Turbine
13.4.2. Theoretical Maximum Efficiency
13.5. Representative Power Curve for a Wind Turbine
13.6. Elementary Wind Models
13.7. Blade Element Model for the Wind Turbine
13.8. Blade Element Momentum Theory for a Wind Turbine
13.8.1. Effect of Number of Blades
13.8.2. Effect of Viscous Drag
13.8.3. Tip-Loss Effects
13.8.4. Tip Losses and Other Viscous Losses
13.8.5. Effects of Stall
13.9. Airfoils for Wind Turbines
13.10. Yawed Flow Operation
13.11. Vortex Wake Considerations
13.12. Unsteady Aerodynamic Effects on Wind Turbines
13.12.1. Tower Shadow
13.12.2. Dynamic Stall and Stall Delay
13.13. Advanced Aerodynamic Modeling Requirements
13.14. Chapter Review
13.15. Questions
Bibliography
14. Computational Methods for Helicopter Aerodynamics
14.1. Introduction
14.2. Fundamental Governing Equations of Aerodynamics
14.2.1. Navier-Stokes Equations
14.2.2. Euler Equations
14.3. Vorticity Transport Equations
14.4. Vortex Methods
14.5. Boundary Layer Equations
14.6. Potential Equations
14.7. Surface Singularity Methods
14.8. Thin Airfoil Theory
14.9. Lifting-Line Blade Model
14.10. Applications of Advanced Computational Methods
14.10.1. Unsteady Airfoil Performance
14.10.2. Tip Vortex Formation
14.10.3. CFD Modeling of the Rotor Wake
14.10.4. Airframe Flows
14.10.5. Vibrations and Acoustics
14.10.6. Ground Effect
14.10.7. Vortex Ring State
14.11. Comprehensive Rotor Analyses
14.12. Chapter Review
14.13. Questions
Bibliography
Appendix
Index

Principles of helicopter aerodynamics /

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