Download or read book Vortex Rings and the Plate Jet written by Percival D. McCormack and published by . This book was released on 1968 with total page 10 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Vortex Rings and Jets written by Daniel T. H. New and published by Springer. This book was released on 2015-03-26 with total page 241 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this book, recent developments in our understanding of fundamental vortex ring and jet dynamics will be discussed, with a view to shed light upon their near-field behaviour which underpins much of their far-field characteristics. The chapters provide up-to-date research findings by their respective experts and seek to link near-field flow physics of vortex ring and jet flows with end-applications in mind. Over the past decade, our knowledge on vortex ring and jet flows has grown by leaps and bounds, thanks to increasing use of high-fidelity, high-accuracy experimental techniques and numerical simulations. As such, we now have a much better appreciation and understanding on the initiation and near-field developments of vortex ring and jet flows under many varied initial and boundary conditions. Chapter 1 outlines the vortex ring pinch-off phenomenon and how it relates to the initial stages of jet formations and subsequent jet behaviour, while Chapter 2 takes a closer look at the behaviour resulting from vortex ring impingement upon solid boundaries and how the use of a porous surface alters the impingement process. Chapters 3 and 4 focus upon the formation of synthetic jets from vortex ring structures experimentally and numerically, the challenges in understanding the relationships between their generation parameters and how they can be utilized in flow separation control problems. Chapter 5 looks at the use of imposing selected nozzle trailing-edge modifications to effect changes upon the near-field dynamics associated with circular, noncircular and coaxial jets, with a view to control their mixing behaviour. And last but not least, Chapter 6 details the use of unique impinging jet configurations and how they may lend themselves towards greater understanding and operating efficacies in heat transfer problems. This book will be useful to postgraduate students and researchers alike who wish to get up to speed regarding the latest developments in vortex ring and jet flow behaviour and how their interesting flow dynamics may be put into good use in their intended applications.
Download or read book Vortex Rings written by D. G. Akhmetov and published by Springer Science & Business Media. This book was released on 2009-11-24 with total page 154 pages. Available in PDF, EPUB and Kindle. Book excerpt: Vortex flow is one of the fundamental types of fluid and gas motion. These flows are the most spectacular in the form of concentrated vortices, characterized by the localization of vorticity (curl of velocity) in bounded regions of a space, beyond which the vorticity is either absent or rapidly falls down to zero. Concentrated vortices are often observed in nature, exemplified by atmospheric cyclones, whirlwinds and tornados, oceanic vortices, whirlpools on a water s- face, and ring vortices caused by explosive outburst of volcanoes. In technical - vices concentrated vortices form when flow separates from sharp edges of flying vehicles and ships. Among these are vortices flowing off the ends of airplane wings, and intentionally generated vortices for intensification of burning in c- bustion chambers, vortices in cyclonic devices used for mixing or separation of impurities in fluids and gases. One such remarkable and frequent type of conc- trated vortices is a vortex ring which constitutes a vortex tube closed into a t- oidal ring moving in a surrounding fluid like an isolated body out of contact with solid boundaries of the flow region if such boundaries exist. Formation and motion of vortex rings are important part of the dynamics of a continuum medium and have been studied for more than a century.
Download or read book Investigation of Synthetic Jets Heat Transfer and Flow Field written by Carlo Salvatore Greco and published by Youcanprint. This book was released on 2015-04-30 with total page 187 pages. Available in PDF, EPUB and Kindle. Book excerpt: Synthetic jets are devices able to “synthetize” a jet from the ambient in which they are embedded through a simple membrane oscillation inside a cavity with an orifice. Such features make them high reliable, silent and easy to be miniaturized. For these reasons, they are widely investigated as electronic cooling devices. The present research is focused on the design and analysis of a different type of synthetic jet device compared to its single classical configuration. Such a device his experimentally characterized through the study of its free and impinging flow field and the evaluation of its heat transfer performance.
Download or read book Application of the Vortex lattice Method to Represent a Jet Exhausting from a Flat Plate Into a Crossflowing Stream written by F. L. Heltsley and published by . This book was released on 1973 with total page 78 pages. Available in PDF, EPUB and Kindle. Book excerpt: A study was conducted to develop a mathematical model of a jet exhausting from a flat plate into a crossflowing stream. The modeling was accomplished using the vortex-lattice method. Analytical streamlines and pressure distributions on the flat-plate surface as well as vector data in the field above the plate are compared with available experimental data. Recommendations are made for further improvement of vortex-lattice jet-modeling techniques. (Author).
Download or read book Vortex Rings Generated by a Shrouded Hartmann Sprenger Tube written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-06-24 with total page 34 pages. Available in PDF, EPUB and Kindle. Book excerpt: The pulsed flow emitted from a shrouded Hartmann-Sprenger tube was sampled with high-frequency pressure transducers and with laser particle imaging velocimetry, and found to consist of a train of vortices. Thrust and mass flow were also monitored using a thrust plate and orifice, respectively. The tube and shroud lengths were altered to give four different operating frequencies. From the data, the radius, velocity, and circulation of the vortex rings was obtained. Each frequency corresponded to a different length to diameter ratio of the pulse of air leaving the driver shroud. Two of the frequencies had length to diameter ratios below the formation number, and two above. The formation number is the value of length to diameter ratio below which the pulse converts to a vortex ring only, and above which the pulse becomes a vortex ring plus a trailing jet. A modified version of the slug model of vortex ring formation was used to compare the observations with calculated values. Because the flow exit area is an annulus, vorticity is shed at both the inner and outer edge of the jet. This results in a reduced circulation compared with the value calculated from slug theory accounting only for the outer edge. If the value of circulation obtained from laser particle imaging velocimetry is used in the slug model calculation of vortex ring velocity, the agreement is quite good. The vortex ring radius, which does not depend on the circulation, agrees well with predictions from the slug model. DeLoof, Richard L. (Technical Monitor) and Wilson, Jack Glenn Research Center NASA/CR-2005-213576, AIAA Paper 2005-5163, E-15041-2
Download or read book A Treatise on the Motion of Vortex Rings written by Sir Joseph John Thomson and published by . This book was released on 1883 with total page 168 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Formation of Orifice generated Vortex Rings written by Raphaël Limbourg and published by . This book was released on 2021 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: "In this dissertation, the formation of vortex rings at the edge of orifices, as opposed to the well-studied nozzle geometry, is experimentally and theoretically investigated using time-resolved planar particle image velocimetry. This thesis builds upon the groundwork of Gharib et al. (1998) on optimal vortex formation and the general study of non-parallel starting jets initiated by Krieg & Mohseni (2013a).The orifice apparatus can be used to model complex geometries observed in nature, such as heart valves or squids' funnel, and constitutes the main equipment to produce synthetic jets and pulsed jets, which can be used for flow control, unsteady heat and mass transfer or thrust generation. Krieg & Mohseni (2013a) studied orifice starting jets and found that this apparatus produces more circulation, hydrodynamic impulse and kinetic energy than the equivalent nozzle geometry. The specific initial boundary conditions of the orifice geometry, namely the non-zero radial velocity at the exhaust, were shown to be responsible for the increased production of the invariants of the motion. Nevertheless, the ring quantities were not measured, as well as the "formation number", as originally defined by Gharib et al. (1998).An objective of the study is therefore to investigate the influence of initial conditions on the formation process of vortex rings and test the validity of the supposedly universal time scale that is the formation number. In particular, it is found that the sharp edge of the orifice destabilises the flow, forming a train of discrete vortices, as opposed to the continuous feeding shear layer observed in the case of nozzles. As such, it is shown that orifice-generated vortex rings do not reach their maximum circulation state at the same instant, and location, as their maximum impulse and energy states.Moreover, covering the exhaust of a tube with an orifice plate introduces an additional geometrical parameter, that is the orifice-to-tube diameter ratio. A parametric study is undertaken to assess the influence of this ratio on the production of the invariants of the motion, which are then related to vortex ring formation. Unsurprisingly, the classic slug-flow model is found to underestimate the rate of production of the invariants, and this for all orifice-to-tube diameter ratios, although in a lesser extent for the nozzle case. An extension to the model is proposed to account for the contraction the flow is experiencing when fluid is being pushed out through the orifice. The contraction coefficient found analytically by Von Mises (1917) for two-dimensional flows is applied to the present axisymmetric three-dimensional cases and the discrepancy with the measurements is reduced from a maximum of 130%, 50% and 120% to 10%, 10% and 25% for the circulation, the hydrodynamic impulse and the kinetic energy, respectivelyFinally, the critical non-dimensional numbers commonly used to characterise vortex ring formation are computed at the exhaust of the orifice geometry. Again, the classic slug-flow model is observed to poorly predict their evolution. It is shown that using the extended slug-flow model to redefine the non-dimensional time, usually referred as "formation time", allows one to collapse all cases, orifices and nozzle, onto a single curve. Hence, given the proposed scaling, a formation number of approximately 4 is found for straight nozzle, converging nozzle and orifice-generated vortex ringsIn conclusions, this thesis not only shows experimental evidence of the difference in the unsteady formation of vortex rings emanating from orifice geometries, but also provides a theoretical explanation and an analytical model which incorporates the unique physical phenomena of orifice starting jets and extends the well-accepted results of the literature, for instance the result of Gharib et al. (1998), to the formation of orifice-generated vortex rings"--
Download or read book Gas Turbine Heat Transfer and Cooling Technology Second Edition written by Je-Chin Han and published by CRC Press. This book was released on 2012-11-27 with total page 892 pages. Available in PDF, EPUB and Kindle. Book excerpt: A comprehensive reference for engineers and researchers, Gas Turbine Heat Transfer and Cooling Technology, Second Edition has been completely revised and updated to reflect advances in the field made during the past ten years. The second edition retains the format that made the first edition so popular and adds new information mainly based on selected published papers in the open literature. See What’s New in the Second Edition: State-of-the-art cooling technologies such as advanced turbine blade film cooling and internal cooling Modern experimental methods for gas turbine heat transfer and cooling research Advanced computational models for gas turbine heat transfer and cooling performance predictions Suggestions for future research in this critical technology The book discusses the need for turbine cooling, gas turbine heat-transfer problems, and cooling methodology and covers turbine rotor and stator heat-transfer issues, including endwall and blade tip regions under engine conditions, as well as under simulated engine conditions. It then examines turbine rotor and stator blade film cooling and discusses the unsteady high free-stream turbulence effect on simulated cascade airfoils. From here, the book explores impingement cooling, rib-turbulent cooling, pin-fin cooling, and compound and new cooling techniques. It also highlights the effect of rotation on rotor coolant passage heat transfer. Coverage of experimental methods includes heat-transfer and mass-transfer techniques, liquid crystal thermography, optical techniques, as well as flow and thermal measurement techniques. The book concludes with discussions of governing equations and turbulence models and their applications for predicting turbine blade heat transfer and film cooling, and turbine blade internal cooling.
Download or read book Experimental Investigations Into Vortex Rings in Pulsed Jets written by Erdoğan Aydemir and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Applied Mechanics Reviews written by and published by . This book was released on 1972 with total page 568 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 1994 with total page 892 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Break Up of Vortex Rings in Impinging Turbulent Jet Flames written by A. J. Yule and published by . This book was released on 1980 with total page 21 pages. Available in PDF, EPUB and Kindle. Book excerpt: This report describes progress on the study of large eddies in flames which has benefited from support by ERO, U.S. Army. The work has clearly demonstrated the existence and importance of the coherent large eddy motions in (1) Gas flames impinging on a flat plate; (2) Free gaseous diffusion flames, and (3) An axisymmetric fuel spray. The measurement programme has developed and used: (1) Simultaneous measurements on velocity, temperature and ionisation level, with the derivation of covariances and spectra; (2) Space-time cross-correlations, using pairs of ionisation probes or thermocouples; (3) Arrays of axially spaced thermocouples, to 'follow' eddies downstreams; and (4) A novel 'top-hat' light-distribution LDA Particle Sizing System for simultaneous measurements of droplet sizes and velocities. (Author).
Download or read book International Journal of Engineering Fluid Mechanics written by and published by . This book was released on 1988 with total page 622 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book AIAA Bulletin written by and published by . This book was released on 1967 with total page 800 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book NBS Special Publication written by and published by . This book was released on 1973 with total page 690 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Hydraulic Research in the United States and Canada written by and published by . This book was released on 1972 with total page 708 pages. Available in PDF, EPUB and Kindle. Book excerpt:
