Download or read book Vortex Pair Instabilities in Ground Effect written by James Gerard Fogg and published by . This book was released on 2001 with total page 202 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Stability of a Vortex Pair in the Presence of a Ground Plane written by Nicholas R. Rotta and published by . This book was released on 1971 with total page 33 pages. Available in PDF, EPUB and Kindle. Book excerpt: The configuration stability of a vortex pair in the presence of a ground plane is examined. First the motion of a vortex in three dimensions is examined by the method of matched asymptotic expansions in which the solution of the Navier-Stokes equations are constructed asymptotically. The dependence of the velocity and stability of the vortex on factors such as the outer(inviscid) flow field and viscosity in the inner (vortical core) region is clearly established. The proximity of the ground plane enters through the outer solution which is matched to the inner, viscosity dependent, solution. The vortex pair in ground effect is shown to be unstable to disturbances of all wavelengths with increasing amplification rate as the ground is approached. Indications are that the present analysis predicts a more stable (less unstable) vortex system than does the inviscid theory. Comparison of the present analysis, in the limit of zero ground effect, with photographs of vortices undergoing a configuration instability is made. The viscosity necessary for agreement is found to be on the order of the eddy viscosity for the turbulent line vortex, indicating the existence of turbulence in the vortex core. (Author).

Download or read book Investigation of Vortex Wake Stability Near the Ground written by I. H. Tombach and published by . This book was released on 1975 with total page 75 pages. Available in PDF, EPUB and Kindle. Book excerpt: Vortex wakes exist in a complicated environment near the ground at airports. Under many situations, factors combine to move a wake sufficiently far from the runway approach corridor that it does not constitute a hazard to following aircraft. Situations exist, however, where a wake can possibly linger at high strength long enough to present operational problems. The sinuous mutual induction instability of a vortex pair has been investigated theoretically and experimentally in atmospheric conditions which prevail near the ground, thereby extending previous work of Crow and Bate for the same instability aloft. Two theoretical models were developed -- one for a vortex pair in the constant stress layer of the atmospheric boundary layer, and the second for a vortex interacting with its image when in ground effect.

Download or read book The Pressure Field of a Vortex Wake in Ground Effect written by Clinton E. Brown and published by . This book was released on 1975 with total page 9 pages. Available in PDF, EPUB and Kindle. Book excerpt: The ground pressures under a descending pair of vortices, such as might be generated by aircraft either landing or taking off are computed. It is found that as the vortices first approach the ground, only positive pressures are produced; however as the descent continues the high velocity field of the vortices makes itself apparent in dips to sub-atmospheric pressure which lie closely beneath the vortex center. Nevertheless, a substantial positive pressure hill precedes the path of the vortex as it moves laterally in the 'ground effect'. The level of pressures produced is dependent only on the flight speed, lift coefficient and aspect ratio while the length scale of the pressure distribution is proportional to the span. These results may be useful in the development of systems to monitor multiple aircraft take-off and/or landing operations.

Download or read book Viscous Effects on a Vortex Wake in Ground Effect written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-07-15 with total page 48 pages. Available in PDF, EPUB and Kindle. Book excerpt: Wake vortex trajectories and strengths are altered radically by interactions with the ground plane. Prediction of vortex strength and location is especially important in the vicinity of airports. Simple potential flow methods have been found to yield reasonable estimates of vortex descent rates in an otherwise quiescent ambient background, but those techniques cannot be adjusted for more realistic ambient conditions and they fail to provide satisfactory estimates of ground-coupled behavior. The authors have been involved in a systematic study concerned with including viscous effects in a wake-vortex system which is near the ground plane. The study has employed numerical solutions to the Navier-Stokes equations, as well as perturbation techniques to study ground coupling with a descending vortex pair. Results of a two-dimensional, unsteady numerical-theoretical study are presented in this paper. A time-based perturbation procedure has been developed which permits the use of analytical solutions to an inner and outer flow domain for the initial flow field. Predictions have been compared with previously reported laminar experimental results. In addition, the influence of stratification and turbulence on vortex behavior near the ground plane has been studied. Zheng, Z. and Ash, Robert L. Unspecified Center NAG1-987...

Download or read book Generation and Evolution of a Viscous Vortex Pair written by Gaurav Gupta and published by . This book was released on 2003 with total page 254 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Initiation of Long Wave Instability of Vortex Pairs at Cruise Altitudes written by National Aeronautics and Space Adm Nasa and published by Independently Published. This book was released on 2019-01-14 with total page 30 pages. Available in PDF, EPUB and Kindle. Book excerpt: Previous studies have usually attributed the initiation of the long-wave instability of a vortex pair to turbulence in the atmosphere or in the wake of the aircraft. The purpose here is to show by use of observations and photographs of condensation trails shed by aircraft at cruise altitudes that another initiating mechanism is not only possible but is usually the mechanism that initiates the long-wave instability at cruise altitudes. The alternate initiating mechanism comes about when engine thrust is robust enough to form an array of circumferential vortices around each jet-engine-exhaust stream. In those cases, initiation begins when the vortex sheet shed by the wing has rolled up into a vortex pair and descended to the vicinity of the inside bottom of the combined shear-layer vortex arrays. It is the in-and-out (up and down) velocity field between sequential circumferential vortices near the bottom of the array that then impresses disturbance waves on the lift-generated vortex pair that initiate the long-wave instability. A time adjustment to the Crow and Bate estimate for vortex linking is then derived for cases when thrust-based linking occurs. Rossow, Vernon J. Ames Research Center WBS 411931.02.61.01.22

Download or read book Initiation of Long Wave Instability of Vortex Pairs at Cruise Altitudes written by Vernon J. Rossow and published by BiblioGov. This book was released on 2013-06 with total page 32 pages. Available in PDF, EPUB and Kindle. Book excerpt: Previous studies have usually attributed the initiation of the long-wave instability of a vortex pair to turbulence in the atmosphere or in the wake of the aircraft. The purpose here is to show by use of observations and photographs of condensation trails shed by aircraft at cruise altitudes that another initiating mechanism is not only possible but is usually the mechanism that initiates the long-wave instability at cruise altitudes. The alternate initiating mechanism comes about when engine thrust is robust enough to form an array of circumferential vortices around each jet-engine-exhaust stream. In those cases, initiation begins when the vortex sheet shed by the wing has rolled up into a vortex pair and descended to the vicinity of the inside bottom of the combined shear-layer vortex arrays. It is the in-and-out (up and down) velocity field between sequential circumferential vortices near the bottom of the array that then impresses disturbance waves on the lift-generated vortex pair that initiate the long-wave instability. A time adjustment to the Crow and Bate estimate for vortex linking is then derived for cases when thrust-based linking occurs.

Download or read book Experimental Investigation of the Dynamics of Counter rotating Vortex Pairs in Ground Effect written by and published by . This book was released on 2006 with total page 64 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Vorticity and Vortex Dynamics written by Jie-Zhi Wu and published by Springer Science & Business Media. This book was released on 2007-04-20 with total page 776 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is a comprehensive and intensive monograph for scientists, engineers and applied mathematicians, as well as graduate students in fluid dynamics. It starts with a brief review of fundamentals of fluid dynamics, with an innovative emphasis on the intrinsic orthogonal decomposition of fluid dynamic process, by which one naturally identifies the content and scope of vorticity and vortex dynamics. This is followed by a detailed presentation of vorticity dynamics as the basis of later development. In vortex dynamics part the book deals with the formation, motion, interaction, stability, and breakdown of various vortices. Typical vortex structures are analyzed in laminar, transitional, and turbulent flows, including stratified and rotational fluids. Physical understanding of vertical flow phenomena and mechanisms is the first priority throughout the book. To make the book self-contained, some mathematical background is briefly presented in the main text, but major prerequisites are systematically given in appendices. Material usually not seen in books on vortex dynamics is included, such as geophysical vortex dynamics, aerodynamic vortical flow diagnostics and management.

Download or read book IUTAM Symposium on Dynamics of Slender Vortices written by Egon Krause and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 473 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book Air Pollution Abstracts written by and published by . This book was released on 1972 with total page 744 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1993 with total page 556 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Research Developments in Sustainable Aviation written by T. Hikmet Karakoc and published by Springer Nature. This book was released on 2023-10-31 with total page 425 pages. Available in PDF, EPUB and Kindle. Book excerpt: Sustainable aviation is a long-term strategy aimed at providing innovative solutions to the challenges facing the aviation industry. The International Symposium on Sustainable Aviation is a multi-disciplinary symposium that presents research on current sustainability-based issues and future trends in the field of aviation from an economic, social, and environmental perspective. The conference provides a platform offering insights on a broad range of current issues in aviation, such as improving aircraft fuel efficiency, fostering the use of biofuels, minimizing environmental impact, mitigating GHG emissions, and reducing engine and airframe noise. ISSA allows researchers, scientists, engineers, practitioners, policymakers, and students to exchange information, present new technologies and developments, and discuss future direction, strategies, and priorities in aviation and sustainability.

Download or read book Issues in Mechanical Engineering 2013 Edition written by and published by ScholarlyEditions. This book was released on 2013-05-01 with total page 1208 pages. Available in PDF, EPUB and Kindle. Book excerpt: Issues in Mechanical Engineering / 2013 Edition is a ScholarlyEditions™ book that delivers timely, authoritative, and comprehensive information about Additional Research. The editors have built Issues in Mechanical Engineering: 2013 Edition on the vast information databases of ScholarlyNews.™ You can expect the information about Additional Research in this book to be deeper than what you can access anywhere else, as well as consistently reliable, authoritative, informed, and relevant. The content of Issues in Mechanical Engineering: 2013 Edition has been produced by the world’s leading scientists, engineers, analysts, research institutions, and companies. All of the content is from peer-reviewed sources, and all of it is written, assembled, and edited by the editors at ScholarlyEditions™ and available exclusively from us. You now have a source you can cite with authority, confidence, and credibility. More information is available at http://www.ScholarlyEditions.com/.

Download or read book Dynamics of Vortex Structures in a Stratified Rotating Fluid written by Mikhail A. Sokolovskiy and published by Springer Science & Business Media. This book was released on 2013-08-28 with total page 392 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents an extensive analysis of the dynamics of discrete and distributed baroclinic vortices in a multi-layer fluid that characterizes the main features of the large and mesoscales dynamics of the atmosphere and the ocean. It widely covers the case of hetonic situations as well as the case of intrathermocline vortices that are familiar in oceanographic and of recognized importance for heat and mass transfers. Extensive typology of such baroclinic eddies is made and analysed with the help of theoretical development and numerical computations. As a whole it gives an overview and synthesis of all the many situations that can be encountered based on the long history of the theory of vortex motion and on many new situations. It gives a renewed insight on the extraordinary richness of vortex dynamics and open the way for new theoretical, observational and experimental advances. This volume is of interest to experts in physical oceanography, meteorology, hydrodynamics, dynamic systems, involved in theoretical, experimental and applied research and lecturers, post-graduate students, and students in these fields.

Download or read book Vortex Shedding of a Circular Cylinder in Ground Effect written by A. Vitale and published by . This book was released on 1978 with total page 72 pages. Available in PDF, EPUB and Kindle. Book excerpt: