PIV Measurements of Compressible Vortex Rings Generated by a Shock Tube PDF Download
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Author: Jacques Haertig
Publisher:
ISBN:
Category :
Languages : en
Pages : 10
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Author: Jacques Haertig
Publisher:
ISBN:
Category :
Languages : en
Pages : 10
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Author: Murugan Thangadurai
Publisher: LAP Lambert Academic Publishing
ISBN: 9783846549032
Category :
Languages : en
Pages : 164
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Book Description
Flow field and acoustic characteristics of compressible vortex ring evolution and its interaction with wall have been investigated for Mach number varying from 1.3 to 1.85 using high speed smoke visualizations and microphone. Importance of vortex ring study, classifications, generation mechanism, parameters that characterize its evolution and time line of vortex rings research since its discovery are discussed in Chap. 1. Shock tube design and theory of shock tube flow with the history and applications of shock tube are discussed in Chap. 2 and appendix A. The spatial and angular variations of incident shock diffracted at the shock tube exit are also studied using hot wire anemometer. The effect of driver section length, its pressure, and various driver section gases on shock strength and uniform flow time is discussed using method of characteristics (MOC) technique. Evolution of primary and counter rotating vortex rings (CRVR) are studied in chap. 3 and 4. Vortex ring diameter increases rapidly and translational velocity decreases during the formation and evolution of CRVR. The shock and wall interaction of vortex ring are discussed in Chap. 5.
Author: Andreas Schröder
Publisher: Springer Science & Business Media
ISBN: 3540735283
Category : Science
Languages : en
Pages : 516
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Book Description
This book summarizes the main results reached using the EC-funded network PivNet 2. It also presents a survey of the state of the art of scientific research using PIV techniques. You get a clear introduction to the basics of these techniques. The authors then guide you through current and possible future applications for flow analysis, including combustion and supersonic flow. Hundreds of illustrations, many in full color, are provided.
Author: Alexander Michael Ames
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Book Description
The initial development and shock acceleration of inhomogeneous compressible vortex rings is experimentally investigated in a vertical shock tube. Vortex rings are created by discharging gas (either N2, Ar, CF4, or SF6) into ambient N2 from the open end of a small, upwards-firing shock tube mounted in the end wall of a large, downwards-firing shock tube. Separation between the two gases is maintained by continuously evacuating excess gas from a slot encircling the open end of the small shock tube. The initial development of the vortex rings across a broad range of ring formation parameters is investigated using high-speed planar laser-induced fluorescence (PLIF) and particle image velocimetry (PIV). Ring formation conditions are controlled by varying the driver pressure ratio p4/p1, producing rings with circulation-based Reynolds numbers between 1×105 and 3×106. The early-time growth of the rings is found to be strongly dependent on the Reynolds number and weakly dependent on the Atwood number. A subset of the ring formation parameters is selected for further investigation following shock acceleration by a M = 2.05 planar shock wave. Ring trajectories and the evolution of geometric parameters are compared to their pre-shock states. Ring circulation is found to increase significantly for the high-Atwood cases due to baroclinic deposition of vorticity, but is found to counterintuitively decrease for the low-Atwood cases. Vorticity deposition due to shock curvature effects around vortex cores is directly observed experimentally for the first time.
Author: D. Das
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Author: Raffaello Mariani
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Experimental studies have been conducted on the topic of the interaction of compressiblevortex rings on stationary surfaces. Throughout the campaign experimentswere carried out at pressure ratios of ! 4, 8, and 12. In the classical set up of airas both the driver and driven gas, these corresponded to theoretical incident Machnumbers Ms of 1.34, 1.54, and 1.61.Experiments were conducted on vortex rings impinging on a stationary surfacelocated at three (increasing) distances (1.66, 3.33, and 5.00 inner diameters) fromthe shock tube exit and on a stationary surface at a set distance but at three anglesinclinations (75, 60, and 45deg at 3.33 inner diameters). Results of the impingementof a vortex ring on a stationary solid surface perpendicular to the flow showed asymmetrical impingement process. A boundary layer is generated over the surfacewith an associated increase in pressure. An increase in velocity due to the radialexpansion causes the pressure over the surface to decrease. This expansion leads tothe development of azimuthal wave instabilities along the core. Pressure was seen toincrease with an increase in incident Mach number value. The variation in distanceresulted in an increase in pressure with an increase in distance. This counter-intuitiveresult can be explained by the higher translational velocity at impingement, alongwith the absence of the initial radial expansion of the counter-rotating vortex rings. The variation in surface angle inclination introduced several degrees of asymmetry. One core of the vortex ring impinges first on the surface due to its closerproximity to it, while the other core is still free to propagate. This process generatesan asymmetric boundary layer over the surface, and a higher rate of stretching ofthe lower core, resulting in its dissipation. At higher incident Mach numbers, theembedded rearward facing shock is reflected and propagates perpendicularly to thesurface. At the inclination angles of 60 and 45deg, the counter-rotating vortex ringsare fully deflected upwards and orbit around the main vortex. This phenomenonresult in a significant difference in pressure distribution between the upper and lowersections of the surface.
Author: Tapan K Sengupta
Publisher: World Scientific
ISBN: 9814635170
Category : Science
Languages : en
Pages : 551
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Book Description
The role of high performance computing in current research on transitional and turbulent flows is undoubtedly very important. This review volume provides a good platform for leading experts and researchers in various fields of fluid mechanics dealing with transitional and turbulent flows to synergistically exchange ideas and present the state of the art in the fields.Contributed by eminent researchers, the book chapters feature keynote lectures, panel discussions and the best invited contributed papers.
Author: D. G. Akhmetov
Publisher: Springer Science & Business Media
ISBN: 3642050166
Category : Technology & Engineering
Languages : en
Pages : 154
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Book Description
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.
Author: National Aeronautics and Space Administration (NASA)
Publisher: Createspace Independent Publishing Platform
ISBN: 9781721791330
Category :
Languages : en
Pages : 34
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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
Author: N. Muniswamy Reddy
Publisher:
ISBN:
Category : Measurement
Languages : en
Pages : 28
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Book Description
Shock tube flow analysis with dimensionless velocity number.
