Download or read book Experimental Study of Vortex Breakdown in a Cylindrical Swirling Flow written by José L. Stevens and published by . This book was released on 1996 with total page 142 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Experimental Study of Vortex Breakdown in a Cylindrical Swirling Flow written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-07-17 with total page 146 pages. Available in PDF, EPUB and Kindle. Book excerpt: The stability of a steady, vortical flow in a cylindrical container with one rotating endwall has been experimentally examined to gain insight into the process of vortex breakdowwn. The dynamics of the flow are governed by the Reynolds number (Re) and the aspect ratio of the cylinder. Re is given by Omega R(sup 2)/nu, where Omega is the speed of rotation of the endwall, R is the cylinder radius, and nu is the kinematic viscosity of the fluid filling the cylinder. The aspect ratio is H/R, where H is the height of the cylinder. Numerical simulation studies disagree whether or not the steady breakdown is stable beyond a critical Reynolds number, Re(sub c). Previous experimental researches have considered the steady and unsteady flows near Re(sub c), but have not explored the stability of the steady breakdown structures beyond this value. In this investigation, laser induced fluorescence was utilized to observe both steady and unsteady vortex breakdown at a fixed H/R of 2.5 with Re varying around Re(sub c). When the Re of a steady flow was slowly increased beyond Re(sub c), the breakdown structure remained steady even though unsteadiness was possible. In addition, a number of hysteresis events involving the oscillation periods of the unsteady flow were noted. The results show that both steady and unsteady vortex breakdown occur for a limited range of Re above Re(sub c). Also, with increasing Re, complex flow transformations take place that alter the period at which the unsteady flow oscillates. Stevens, J. L. and Celik, Z. Z. and Cantwell, B. J. and Lopez, J. M. Ames Research Center VORTEX BREAKDOWN; SWIRLING; FLOW STABILITY; STEADY FLOW; INTERNAL FLOW; REYNOLDS NUMBER; CYLINDRICAL BODIES; ASPECT RATIO; AXISYMMETRIC FLOW; FLOW VISUALIZATION; OSCILLATIONS; PERTURBATION; BUBBLES; UNSTEADY FLOW; VISCOSITY; LASER INDUCED FLUORESCENCE...
Download or read book Experimental Study of Vortex Breakdown and Its Control in Swirling Flow written by Dina Fastovsky and published by . This book was released on 2007 with total page 144 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book An Experimental Investigation of the Vortex breakdown Phenomenon written by Turgut Sarpkaya and published by . This book was released on 1970 with total page 66 pages. Available in PDF, EPUB and Kindle. Book excerpt: The results of an experimental investigation of the characteristics of stationary and travelling vortex breakdowns in swirling flow in a diverging cylindrical tube are presented and discussed. Basically, three types of vortex breakdown were observed, viz., double helix, spiral, and axisymmetric breakdown. The type and location of the stationary breakdowns were found to be dependent upon the Reynolds and circulation numbers of the flow. The breakdown bubble responded to gradual and abrupt changes in the upstream and downstream flow conditions in a manner analogous to the hydraulic jump in open-channel flow. The observations reported and the evidence presented revealed unmistakably that the vortex breakdown is a finite transition from a uniform state of swirling flow (supercritical) to one (subcritical) featuring a large standing wave, followed by standing wavelets, of finite amplitude. (Author).
Download or read book Oscillatory Behavior in Vortex Breakdown Flows written by Amrish Kumar Garg and published by . This book was released on 1977 with total page 550 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book On a Criterion for Vortex Breakdown written by R. E. Spall and published by . This book was released on 1987 with total page 28 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Numerical Simulation of Vortex Breakdown by the Vortex filament Method written by Y. Nakamura and published by . This book was released on 1983 with total page 20 pages. Available in PDF, EPUB and Kindle. Book excerpt: The vortex-filament method was applied to the simulation of vortex breakdown. The principal vortex region was represented by multiple filaments, and an axial velocity component was induced by a spiral winding of the filaments. First, an accuracy check was performed for a cylindrical swirling flow field that can be simulated to any accuracy by increasing the number of filaments. Second, an axisymmetric-type vortex breakdown was simulated, with experimental data serving asupstream conditions. The calculated axial- and theta-velocity contours show the breakdown of the vortex, including a rapid change in the vortex core, followed axially by a recovery zone and then a second breakdown. When three-dimensional initial data are used the second breakdown appears to be out of the spiral type in correspondence with experimental observations. The present method can easily be used to simulate other types of vortex breakdown or other vortex flows with axial velocity.
Download or read book An Experimental Investigation of Vortex Breakdown in Tubes at High Reynolds Numbers written by Francis G. Novak and published by . This book was released on 1998-09-01 with total page 336 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Download or read book Theory of Concentrated Vortices written by S. V. Alekseenko and published by Springer Science & Business Media. This book was released on 2007-08-29 with total page 505 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Download or read book Experimental Study of Turbulent Swirling Flows written by Bach Thien Vu and published by . This book was released on 1983 with total page 464 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book A Theoretical and Experimental Study of Vortex Breakdown written by Ken Chi Kien Cheung and published by . This book was released on 1993 with total page 164 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Some Experiments in Swirling Flows written by James Henry Faler and published by . This book was released on 1976 with total page 496 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Experimental Study of Vortex Flow in a Cylinder written by Edward Joseph Palanek (CAPT, USAF.) and published by . This book was released on 1966 with total page 156 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book A Numerical Study of Instability and Vortex Breakdown of Swirling Flow written by Dario Amirante and published by . This book was released on 2007 with total page 186 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book An Experimental Study of Vortex Breakdown written by David Roy Fitzjarrald and published by . This book was released on 1974 with total page 138 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Topology Based Methods in Visualization II written by Hans-Christian Hege and published by Springer Science & Business Media. This book was released on 2009-02-07 with total page 194 pages. Available in PDF, EPUB and Kindle. Book excerpt: Visualization research aims to provide insight into large, complicated data sets and the phenomena behind them. While there are di?erent methods of reaching this goal, topological methods stand out for their solid mathem- ical foundation, which guides the algorithmic analysis and its presentation. Topology-based methods in visualization have been around since the beg- ning of visualization as a scienti?c discipline, but they initially played only a minor role. In recent years,interest in topology-basedvisualization has grown andsigni?cantinnovationhasledto newconceptsandsuccessfulapplications. The latest trends adapt basic topological concepts to precisely express user interests in topological properties of the data. This book is the outcome of the second workshop on Topological Methods in Visualization, which was held March 4–6, 2007 in Kloster Nimbschen near Leipzig,Germany.Theworkshopbroughttogethermorethan40international researchers to present and discuss the state of the art and new trends in the ?eld of topology-based visualization. Two inspiring invited talks by George Haller, MIT, and Nelson Max, LLNL, were accompanied by 14 presentations by participants and two panel discussions on current and future trends in visualization research. This book contains thirteen research papers that have been peer-reviewed in a two-stage review process. In the ?rst phase, submitted papers where peer-reviewed by the international program committee. After the workshop accepted papers went through a revision and a second review process taking into account comments from the ?rst round and discussions at the workshop. Abouthalfthepapersconcerntopology-basedanalysisandvisualizationof ?uid?owsimulations;twopapersconcernmoregeneraltopologicalalgorithms, while the remaining papers discuss topology-based visualization methods in application areas like biology, medical imaging and electromagnetism.
Download or read book Cellular Flows written by Vladimir Shtern and published by Cambridge University Press. This book was released on 2018-02-08 with total page 590 pages. Available in PDF, EPUB and Kindle. Book excerpt: A cell, whose spatial extent is small compared with a surrounding flow, can develop inside a vortex. Such cells, often referred to as vortex breakdown bubbles, provide stable and clean flame in combustion chambers; they also reduce the lift force of delta wings. This book analyzes cells in slow and fast, one- and two-fluid flows and describes the mechanisms of cell generation: (a) minimal energy dissipation, (b) competing forces, (c) jet entrainment, and (d) swirl decay. The book explains the vortex breakdown appearance, discusses its features, and indicates means of its control. Written in acceptable, non-math-heavy format, it stands to be a useful learning tool for engineers working with combustion chambers, chemical and biological reactors, and delta-wing designs.
