The flight of insects has fascinated physicists and biologists for more than a century. Yet, until recently, researchers were unable to rigorously quantify the complex wing motions of flapping insects or measure the forces and flows around their wings. However, recent developments in high-speed videography and tools for computational and mechanical modeling have allowed researchers to make rapid progress in advancing our understanding of insect flight. These mechanical and computational fluid dynamic models, combined with modern flow visualization techniques, have revealed that the fluid dynamic phenomena underlying flapping flight are different from those of non-flapping, 2-D wings on which most previous models were based. In particular, even at high angles of attack, a prominent leading edge vortex remains stably attached on the insect wing and does not shed into an unsteady wake, as would be expected from non-flapping 2-D wings. Its presence greatly enhances the forces generated by the wing, thus enabling insects to hover or maneuver. In addition, flight forces are further enhanced by other mechanisms acting during changes in angle of attack, especially at stroke reversal, the mutual interaction of the two wings at dorsal stroke reversal or wing-wake interactions following stroke reversal. This progress has enabled the development of simple analytical and empirical models that allow us to calculate the instantaneous forces on flapping insect wings more accurately than was previously possible. It also promises to foster new and exciting multi-disciplinary collaborations between physicists who seek to explain the phenomenology, biologists who seek to understand its relevance to insect physiology and evolution, and engineers who are inspired to build micro-robotic insects using these principles. This review covers the basic physical principles underlying flapping flight in insects, results of recent experiments concerning the aerodynamics of insect flight, as well as the different approaches used to model these phenomena.

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The aerodynamics of insect flight

Wind energy explained

Turbomachinery is a challenging and diverse field, with applications for professionals and students in many subsets of the mechanical engineering discipline, including fluid mechanics, combustion and heat transfer, dynamics and vibrations, as well as structural mechanics and materials engineering. Originally published more than 40 years ago, Fluid Mechanics and Thermodynamics of Turbomachinery is the leading turbomachinery textbook. Used as a core text in senior undergraduate and graduate level courses this book will also appeal to professional engineers in the aerospace, global power, oil & gas and other industries who are involved in the design and operation of turbomachines. For this new edition, author S. Larry Dixon is joined by Cesare Hall from the University of Cambridge, whose diverse background of teaching, research and work experience in the area of turbomachines is well suited to the task of reorganizing and updating this classic text. NEW AND KEY FEATURES * Provides the most comprehensive coverage of the fundamentals of turbomachinery of any text in the field* Content has been reorganized to more closely match how instructors currently teach the course* Coverage of fluid mechanics and thermodynamics, the basis on which good turbomachine performance depends, has been moved to the front of the book* Includes new design studies of several turbomachines, applying the theories developed in the book* Figures have been updated, along with new photos added, to better illustrate the topics presented* Includes new examples and additional end-of-chapter exercises

Fluid mechanics, thermodynamics of turbomachinery

Power and thrust measurements of marine current turbines under various hydrodynamic flow conditions in a cavitation tunnel and a towing tank

▪ Abstract “What force does an insect wing generate?” Finding answers to this enduring question is an essential step toward our understanding of interactions of moving objects with fluids that enable most living species such as insects, birds, and fish to travel efficiently and us to follow similar suit with sails, oars, and airfoils. We give a brief history of research in insect flight and discuss recent findings in unsteady aerodynamics of flapping flight at intermediate range Reynolds numbers (10–104). In particular, we examine the unsteady mechanisms in uniform and accelerated motions, forward and hovering flight, as well as passive flight of free-falling objects. The results obtained by “taking the insects apart” helped us to resolve previous puzzles about the force estimates in hovering insects, to ellucidate basic mechanisms essential to flapping flight, and to gain insights about the efficieny of flight.

/pdf/dissecting-insect-flight-4vev0p1a7e.pdf

Dissecting insect flight

1. Introduction 2. Bernoulli's equation 3. The stream function 4. Circulation and vorticity 5. The velocity potential and the potential function 6. The transformation of a circle into an aerofoil 7. The aerofoil in two dimensions 8. Viscosity and drag 9. The basis of aerofoil theory 10. The aerofoil in three dimensions 11. The monoplane aerofoil 12. The flow round an acerofoil 13. Biplane aerofoils 14. Wind tunnel interference on areofoils 15. The airscrew: momentum theory 16. The airscrew: blade element theory 17. The airscrew: wind tunnel interference Appendix Bibliography Index.

H. Glauert

Papers

The elements of aerofoil and airscrew theory

Wind Tunnel Interference on Wings, Bodies and Airscrews

Die Grundlagen der Tragflügel- und Luftschraubentheorie

Induced flow through a partially choked pipe