Flow Control Through Bio-inspired Leading-edge Tubercles: Morphology, Aerodynamics, Hydrodynamics and Applications

Description

This book describes and explains the basis of bio-inspired, leading-edge tubercles based on humpback whale flippers as passive but effective flow control devices, as well as providing a comprehensive practical guide in their applications.  It first discusses the morphology of the humpback whale flipper from a biological perspective, before presenting detailed experimental and numerical findings from past investigations by various experts on the benefits of leading-edge tubercles and their engineering implementations. Leading-edge tubercle designs and functions have attracted considerable interest from researchers in terms of understanding their role in the underwater agility of these whales, and to exploit their flow dynamics in the development of new and novel engineering solutions.  Extensive research over the past recent years has demonstrated that the maneuverability of these whales is at least in part due to the leading-edge tubercles acting as passive flow control devices to delay stall and increase lift in the post-stall regime.  In addition to the inherent benefits in terms of aerodynamics and hydrodynamics, investigations into leading-edge tubercles have also broadened into areas of noise attenuation, stability and industrial applications. This book touches upon these areas, with an emphasis upon the effects of lifting-surface types, flow regimes, tubercle geometries, lifting-surface stability and potential industrial applications, among others.  As such, it features contributions from key experts in the fields of biology, physics and engineering who have conducted significant studies into understanding the various aspects of leading-edge tubercles.  Given the broad coverage and in-depth analysis, this book will benefit academic researchers, practicing engineers and graduate students interested in tapping into such a unique but highly functional flow control strategy. Foreword Preface Contents Biomimetics and the Application of the Leading-Edge Tubercles of the Humpback Whale Flipper 1 Introduction 2 Biomimetics 3 Biology 3.1 Humpback Whale 3.2 Flippers and Tubercles 3.3 Swimming Performance and Foraging Behavior 3.4 Hydrodynamic Implications 3.5 Other Biological Leading-Edge Structures 4 Engineering 4.1 Early Studies 4.2 Wind and Water Tunnel Testing 4.3 Computational Fluid Dynamics 5 Applications 5.1 Scale and the Whale 5.2 Patents 5.3 Control Surfaces-Rudders and Dive Planes 5.4 Wings 5.5 Land Vehicles 5.6 Propellers 5.7 Fans and Compressors 5.8 Turbines 5.9 Noise Reduction 6 Conclusion References Tubercled Wing Flow Physics and Performance 1 Introduction 2 Flow Physics 2.1 Vortex Generators 2.2 Rounded Delta Wings 2.3 Variation of the Effective Angle-of-Attack 2.4 Spanwise Progression of Stall 2.5 Varying Spanwise Circulation 2.6 Enhanced Momentum and Energy Transfer 2.7 Formation of a Vorticity Canopy 2.8 Weakening of the Suction Peak 2.9 Flow Instability 3 The Effects of Reynolds Number 4 Unswept Full-Span Wing Performance 5 Finite-Span Unswept Wings 6 Swept Wing Performance 7 Aeroacoustics 8 Conclusion References Tubercle Geometric Configurations: Optimization and Alternatives 1 Optimization of the Tubercle Geometry on Full-Span Airfoils 2 Optimization of the Tubercle Geometry on Finite-Span Wings 2.1 Tubercle Spacing, Amplitude and Phase 2.2 Tubercle Alignment 2.3 Tubercle Distribution 2.4 Single Tubercle 3 Alternative Geometries 4 Conclusion References Flow Control by Hydrofoils with Leading-Edge Tubercles 1 Introduction 2 Experimental Approaches and Hydrofoil Designs 3 Effects of LE Tubercles on Cambered Hydrofoils 4 Formation and Behaviour of Streamwise CVPs at High AoAs 5 Oscillating LE Tubercled Hydrofoil 6 Conclusions References Leading-Edge Tubercles on Swept and Delta Wing Configurations 1 Background 2 Flipper Wing 3 Swept Wing 4 Delta Wing 5 Conclusion References Effects of Leading-Edge Tubercles on Dynamically Pitching Airfoils 1 Introduction 2 Review of Tubercle Effects on Static Wings 3 Fundamental Dynamic Stall with Tubercled Wings 4 Applied Performance Benefits of Wings Experiencing Dynamic Stall 5 Conclusion References Effects of Leading-Edge Tubercles on Structural Dynamics and Aeroelasticity 1 Introduction 2 Structural Considerations of LE Tubercles 3 Effects of Tubercles on Structural Modes of Vibration 3.1 Tubercles with Zero Phase Lead 3.2 Tubercles with π Phase Lead 4 Effect of Tubercle Geometry on Aeroelastic Stability 4.1 Aeroelastic Formulation 4.2 Effect of LE Tubercles on the Aerodynamics in Pitch Motions 4.3 Effect of Tubercles on Aeroelastic Stability 5 Spanwise Variation of Tubercle Geometry 6 Sweptback Configurations 6.1 Effect of Tubercle Amplitude 6.2 Effect of Tubercle Wavelength 7 Conclusion References Index