Vortex-wall Interactions and Sports-inspired Airfoil Motions

Vortex-wall Interactions and Sports-inspired Airfoil Motions
Author: Sarah Elizabeth Morris
Publisher:
Total Pages: 176
Release: 2020
Genre:
ISBN:

Understanding vortex-wall interactions has applications in the context of airplane trailing vortices, as wake vortices are an unavoidable by-product of aerodynamic lift. These vortices pose an increased hazard for aircraft at airport takeoffs and landings, as following aircraft flying through a vortex wake can experience dangerous rolling moments. In this work, we use a vortex generator tank and a delta wing in an XY-Towing Tank to study the dynamics of counter-rotating vortex pairs both in and out of ground effect, via PIV and flow visualization. When a vortex pair approaches a ground plane, the boundary layer that forms on the surface between the vortices and the wall separates, generating secondary vorticity and causing the primary vortex pair to ``rebound'' from the wall. Using a vortex generator tank to produce a temporally evolving vortex pair, it is shown that the introduction of perturbations at the ground plane results in earlier localized secondary vorticity generation. This leads to the formation of coherent secondary vortex structures, and an accelerated decay of the primary vortex pair. This passive, ground-based method could be a means to diminish the wake vortex hazard behind aircraft close to the ground. We study also the spatially evolving trailing vortices in the far-wake of a 75 degree leading-edge sweep-angle delta wing, using a novel technique to measure the axial flow in the vortex core. This technique is unaffected by vortex wandering, allowing us to capture axial flow data as close as 0.03 chord-lengths apart. Using this technique, the streamwise velocity profile is captured over 20 chord-lengths downstream of the delta wing, even when the vortex pair is in ground effect. In this thesis, we also study new modes of NACA 0012 airfoil motions using a ``sports-mimetic'' approach, inspired by the bodyweight motions of Olympic sailors as they maneuver their sailboats when racing. Olympic sailors use various unsteady aerodynamic techniques when racing to increase propulsion for their boat. One such technique is for sailors to use bodyweight movements to roll the boat about its longitudinal axis. This motion is used especially when turning in light winds by either ``roll tacking'' (upwind sailing) or ``roll gybing'' (downwind sailing); it is also used in ``sail flicking'' whereby the sailor rolls the boat, flicking the sail periodically. These motions are characterized in on-the-water experiments using a Laser sailboat and a 420 sailboat, equipped with a GPS, IMU, wind sensor and GoPro camera array. We study the underlying vortex dynamics of these maneuvers using these characteristic motions, along with full-scale flow visualization and laboratory experiments. Flow visualization experiments are conducted on Cayuga Lake with an Olympic Laser Sailboat, using an Enola Gaye WP40 smoke grenade to visualize large-scale flow features around the sail.

Aerodynamics of a Lifting System in Extreme Ground Effect

Aerodynamics of a Lifting System in Extreme Ground Effect
Author: Kirill V. Rozhdestvensky
Publisher: Springer Science & Business Media
Total Pages: 358
Release: 2013-03-09
Genre: Technology & Engineering
ISBN: 3662042401

This book is dedicated to the memory of a distinguished Russian engineer, Rostislav E. Alexeyev, who was the first in the world to develop the largest ground effect machine - Ekranoplan. One of Alexeyev's design concepts with the aerodynamic configuration of a jlying wing can be seen on the front page. The book presents a description of a mathematical model of flow past a lifting system, performing steady and unsteady motions in close proximity to the underlying solid surface (ground). This case is interesting for practical purposes because both the aerodynamic and the economic efficiency of the system near the ground are most pronounced. Use of the method of matched asymptotic expansions enables closed form solutions for the aerodynamic characteristics of the wings-in-ground effect. These can be used for design, identification, and processing of experimental data in the course of developing ground effect vehicles. The term extreme ground effect, widely used through out the book, is associated with very small relative ground clearances of the order of 10% or less. The theory of a lifting surface, moving in immediate proximity to the ground, represents one of the few limiting cases that can be treated analytically. The author would like to acknowledge that this work has been influenced by the ideas of Professor Sheila E. Widnall, who was the first to apply the matched asymptotics techniques to treat lifting flows with the ground effect. Saint Petersburg, Russia February 2000 Kirill V. Rozhdestvensky Contents 1. Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

A Physical Introduction to Fluid Mechanics

A Physical Introduction to Fluid Mechanics
Author: Alexander J. Smits
Publisher: Wiley-VCH
Total Pages: 552
Release: 2000
Genre: Science
ISBN:

Uncover Effective Engineering Solutions to Practical Problems With its clear explanation of fundamental principles and emphasis on real world applications, this practical text will motivate readers to learn. The author connects theory and analysis to practical examples drawn from engineering practice. Readers get a better understanding of how they can apply these concepts to develop engineering answers to various problems. By using simple examples that illustrate basic principles and more complex examples representative of engineering applications throughout the text, the author also shows readers how fluid mechanics is relevant to the engineering field. These examples will help them develop problem-solving skills, gain physical insight into the material, learn how and when to use approximations and make assumptions, and understand when these approximations might break down. Key Features of the Text * The underlying physical concepts are highlighted rather than focusing on the mathematical equations. * Dimensional reasoning is emphasized as well as the interpretation of the results. * An introduction to engineering in the environment is included to spark reader interest. * Historical references throughout the chapters provide readers with the rich history of fluid mechanics.

Vortical Flows

Vortical Flows
Author: Jie-Zhi Wu
Publisher: Springer
Total Pages: 453
Release: 2015-06-23
Genre: Technology & Engineering
ISBN: 3662470616

This book is a comprehensive and intensive book for graduate students in fluid dynamics as well as scientists, engineers and applied mathematicians. Offering a systematic introduction to the physical theory of vortical flows at graduate level, it considers the theory of vortical flows as a branch of fluid dynamics focusing on shearing process in fluid motion, measured by vorticity. It studies vortical flows according to their natural evolution stages,from being generated to dissipated. As preparation, the first three chapters of the book provide background knowledge for entering vortical flows. The rest of the book deals with vortices and vortical flows, following their natural evolution stages. Of various vortices the primary form is layer-like vortices or shear layers, and secondary but stronger form is axial vortices mainly formed by the rolling up of shear layers. Problems are given at the end of each chapter and Appendix, some for helping understanding the basic theories, and some involving specific applications; but the emphasis of both is always on physical thinking.

Viscous Fluid Flow

Viscous Fluid Flow
Author: Frank M. White
Publisher:
Total Pages: 614
Release: 1991
Genre: Viscous flow
ISBN: 9780071009959

Designed for higher level courses in viscous fluid flow, this text presents a comprehensive treatment of the subject. This revision retains the approach and organization for which the first edition has been highly regarded, while bringing the material completely up-to-date. It contains new information on the latest technological advances and includes many more applications, thoroughly updated problems and exercises.

Fluid Mechanics

Fluid Mechanics
Author: Pijush K. Kundu
Publisher: Academic Press
Total Pages: 919
Release: 2012
Genre: Science
ISBN: 0123821002

Suitable for both a first or second course in fluid mechanics at the graduate or advanced undergraduate level, this book presents the study of how fluids behave and interact under various forces and in various applied situations - whether in the liquid or gaseous state or both.

Fox and McDonald's Introduction to Fluid Mechanics

Fox and McDonald's Introduction to Fluid Mechanics
Author: Robert W. Fox
Publisher: John Wiley & Sons
Total Pages: 608
Release: 2020-06-30
Genre: Science
ISBN: 1119721024

Through ten editions, Fox and McDonald's Introduction to Fluid Mechanics has helped students understand the physical concepts, basic principles, and analysis methods of fluid mechanics. This market-leading textbook provides a balanced, systematic approach to mastering critical concepts with the proven Fox-McDonald solution methodology. In-depth yet accessible chapters present governing equations, clearly state assumptions, and relate mathematical results to corresponding physical behavior. Emphasis is placed on the use of control volumes to support a practical, theoretically-inclusive problem-solving approach to the subject. Each comprehensive chapter includes numerous, easy-to-follow examples that illustrate good solution technique and explain challenging points. A broad range of carefully selected topics describe how to apply the governing equations to various problems, and explain physical concepts to enable students to model real-world fluid flow situations. Topics include flow measurement, dimensional analysis and similitude, flow in pipes, ducts, and open channels, fluid machinery, and more. To enhance student learning, the book incorporates numerous pedagogical features including chapter summaries and learning objectives, end-of-chapter problems, useful equations, and design and open-ended problems that encourage students to apply fluid mechanics principles to the design of devices and systems.

Distinct Aerodynamics of Insect-Scale Flight

Distinct Aerodynamics of Insect-Scale Flight
Author: Csaba Hefler
Publisher: Cambridge University Press
Total Pages: 104
Release: 2021-05-27
Genre: Technology & Engineering
ISBN: 110887522X

Insect-scale flapping wing flight vehicles can conduct environmental monitoring, disaster assessment, mapping, positioning and security in complex and challenging surroundings. To develop bio-inspired flight vehicles, systematic probing based on the particular category of flight vehicles is needed. This Element addresses the aerodynamics, aeroelasticity, geometry, stability and dynamics of flexible flapping wings in the insect flight regime. The authors highlight distinct features and issues, contrast aerodynamic stability between rigid and flexible wings, present the implications of the wing-aspect ratio, and use canonical models and dragonflies to elucidate scientific insight as well as technical capabilities of bio-inspired design.