An Experimental Investigation of Vortex Breakdown in Tubes at High Reynolds Numbers PDF Download
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Author: Francis G. Novak
Publisher:
ISBN: 9781423557371
Category :
Languages : en
Pages : 336
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Book Description
This thesis deals with non-cavitating swirling flows with vortex breakdown in various tubes. Phenomenological and quantitative investigations were carried out at Reynolds numbers as high as 300,000. It was shown that a high Re(D) vortex transitions to its new state (breaks down) via a rapidly spinning spiral form, as demonstrated with 4,000 frame per second video, short exposure time (6 ns) imaging, and Digital Particle Image Velocimetry. Of the known types, the spiral emerges as the fundamental breakdown form and the axisymmetric bubble may now be regarded as a relatively low Re(D) occurrence that is bypassed at sufficiently high Re(D). Some new phenomena were observed at high Re(D): Extremely rapid spiral rotation (over 1,000 revolutions per second), core bifurcation, and changes in the sense of the spiral windings. Familiar features of breakdowns, such as the transition from a jet-like to wake-like axial velocity profile and the rapidly expanding vortex core, were observed in extensive time averaged velocity and turbulence results ascertained with Laser Doppler Velocimetry. However, a mean stagnation point and recirculation were absent in the highest Re(D) flow. The core meandering and stagnation point darting in the turbulent flow field were quantified and discussed in detail.
Author: Francis G. Novak
Publisher:
ISBN: 9781423557371
Category :
Languages : en
Pages : 336
Get Book Here
Book Description
This thesis deals with non-cavitating swirling flows with vortex breakdown in various tubes. Phenomenological and quantitative investigations were carried out at Reynolds numbers as high as 300,000. It was shown that a high Re(D) vortex transitions to its new state (breaks down) via a rapidly spinning spiral form, as demonstrated with 4,000 frame per second video, short exposure time (6 ns) imaging, and Digital Particle Image Velocimetry. Of the known types, the spiral emerges as the fundamental breakdown form and the axisymmetric bubble may now be regarded as a relatively low Re(D) occurrence that is bypassed at sufficiently high Re(D). Some new phenomena were observed at high Re(D): Extremely rapid spiral rotation (over 1,000 revolutions per second), core bifurcation, and changes in the sense of the spiral windings. Familiar features of breakdowns, such as the transition from a jet-like to wake-like axial velocity profile and the rapidly expanding vortex core, were observed in extensive time averaged velocity and turbulence results ascertained with Laser Doppler Velocimetry. However, a mean stagnation point and recirculation were absent in the highest Re(D) flow. The core meandering and stagnation point darting in the turbulent flow field were quantified and discussed in detail.
Author: S. V. Alekseenko
Publisher: Springer Science & Business Media
ISBN: 3540733760
Category : Technology & Engineering
Languages : en
Pages : 505
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Book Description
This book presents comprehensive and authoritative coverage of the wide field of concentrated vortices observed in nature and technique. The methods for research of their kinematics and dynamics are considered. Special attention is paid to the flows with helical symmetry. The authors have described models of vortex structures used for interpretation of experimental data which serve as a ground for development of theoretical and numerical approaches to vortex investigation.
Author:
Publisher:
ISBN:
Category : Aeronautics
Languages : en
Pages : 704
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Book Description
Author:
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ISBN:
Category : Science
Languages : en
Pages : 912
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Book Description
Author: Pankaj Pathak
Publisher: Springer Nature
ISBN: 3030579239
Category : Technology & Engineering
Languages : en
Pages : 326
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Book Description
This book reviews alternative and renewable energy resources in order to pave the way for a more sustainable production in the future. A multi-disciplinary team of authors provides a comprehensive overview of current technologies and future trends, including solar technologies, wind energy, hydropower, microbial electrochemical systems and various biomass sources for biofuel production. In addition, the book focuses on solutions for developing countries. Conventional energy sources are finite, and estimates suggest that they will be exhausted within a few decades. Finding a solution to this problem is a global challenge, and developing countries in particular are still highly dependent on fossil fuels due to their rapidly growing populations accompanied by a huge growth in primary energy consumption. Moreover, the most common conventional energy sources (coal and petroleum) are non-sustainable since their combustion exponentially increases greenhouse gas emissions. As such, there is a pressing need for clean energy based on alternative or renewable resources, not only to ensure energy supplies at an affordable price but also to protect the environment.
Author:
Publisher:
ISBN:
Category : Science
Languages : en
Pages : 616
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ISBN:
Category : Nuclear energy
Languages : en
Pages : 124
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Book Description
Author:
Publisher:
ISBN:
Category : Aeronautics
Languages : en
Pages : 1020
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Book Description
Author:
Publisher:
ISBN:
Category : Mechanics, Applied
Languages : en
Pages : 918
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Book Description
Author: Egon Krause
Publisher: Springer Science & Business Media
ISBN: 9401150427
Category : Technology & Engineering
Languages : en
Pages : 473
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Book Description
The decision of the General Assembly of the International Union of Theoretical and Applied Mechanics to organize a Symposium on Dynamics of Slender Vortices was greeted with great enthusiasm. The acceptance of the proposal, forwarded by the Deutsches Komitee fiir Mechanik (DEKOMECH) signalized, that there was a need for discussing the topic chosen in the frame the IUTAM Symposia offer. Also the location of the symposium was suitably chosen: It was decided to hold the symposium at the RWTH Aachen, where, years ago, Theodore von Karman had worked on problems related to those to be discussed now anew. It was clear from the beginning of the planning, that the symposium could only be held in the von Karman-Auditorium ofthe Rheinisch-Westfalische Technische Hochschule Aachen, a building named after him. The symposium was jointly organized by the editors of this volume, strongly supported by the local organizing committee. The invitations of the scientific committee brought together scientists actively engaged in research on the dynamics of slender vortices. It was the aim of the committee to have the state of the art summarized and also to have the latest results of specific problems investigated communicated to the participants of the symposium. The topics chosen were asymptotic theories, numerical methods, vor tices in shear layers, interaction of vortices, vortex breakdown, vortex sound, and aircraft and helicopter vortices.
