The distortion of a jet by tabs

Bradbury, L. J. S.; Khadem, Ali Hadi.

doi:10.1017/s0022112075002352

Cited by 288 publications

(116 citation statements)

References 5 publications

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“…The entering vorticity is, therefore, tangent to the isobars. Its orientation at x D 0 will, however, be governed by the transport equation (1).…”

Section: Tabbed Geometry Upstream Resultsmentioning

confidence: 99%

“…The basis for item 2 has been describedin detail by Lighthill 5 and Panton. 6 The presentationby Panton is considered to be particularly instructivegiven its emphasison the differencebetween the presence of vorticity at the wall (analogous to wall temperature) and the ux Presented as Paper 96-0545 at the AIAA 34th Aerospace Sciences Meeting, Reno, NV, Jan. [15][16][17][18]1996; received May 29, 1997; revision received Sept. 16,1998; accepted for publication Oct. 1,1998 …”

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confidence: 99%

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Near Exit Plane Effects Caused by Primary and Primary-Plus-Secondary Tabs

Bohl

Foss

1999

AIAA Journal

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Triangular-shaped tabs, attached to the separation lip of a nozzle, have been shown to provide substantial increases in the convective transport-mixing in a jet's near eld. Detailed information is reported on the basic features of such tab ows made available by 1) the large-scale tab and 2) the nely resolved pressure/velocity measurements. Secondary tabs were placed next to, and pointed away from, the primary tab; the motivation was to enhance the outward directed ow from the jet's core region. The strong mixing enhancement, provided by these optimally oriented (pitch angle = 40 deg) secondary tabs, is detailed.

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“…The entering vorticity is, therefore, tangent to the isobars. Its orientation at x D 0 will, however, be governed by the transport equation (1).…”

Section: Tabbed Geometry Upstream Resultsmentioning

confidence: 99%

mentioning

confidence: 99%

Near Exit Plane Effects Caused by Primary and Primary-Plus-Secondary Tabs

Bohl

Foss

1999

AIAA Journal

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“…The technique that has therefore received most attention to date is a passive control device involving use of solid tabs [4][5][6][7]. Tabs are small protrusions placed at the jet nozzle exit; usually more than one is used, spaced around the jet periphery.…”

Section: Introductionmentioning

confidence: 99%

Active flow control of jet mixing using steady and pulsed fluid tabs

Behrouzi

Tao

McGuirk

2008

Proceedings of the Institution of Mechanical Engineers, Part I:

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• This is an article from the journal, Proceedings of the In- This item was submitted to Loughborough's Institutional Repository (https://dspace.lboro.ac.uk/) by the author and is made available under the following Creative Commons Licence conditions.For the full text of this licence, please go to: http://creativecommons.org/licenses/by-nc-nd/2.5/ Active flow control of jet mixing using steady and pulsed fluid tabs P Behrouzi, T Feng, and J J McGuirk* Department of Aero and Auto Engineering, Loughborough University, Loughborough, UKThe manuscript was received on 4 January 2008 and was accepted after revision for publication on 31 March 2008. DOI: 10.1243/09596518JSCE543Abstract: Flow control techniques for increasing the rate of jet mixing in axisymmetric nozzle flows have been investigated. A combination of water tunnel and high-speed airflow facilities is used to assess the near-field jet behaviour. Solid tabs, steady fluid tabs (i.e. discrete radially discharged control jets located close to the core jet exit), and pulsed fluid tabs are compared. The effect of fluid tab velocity amplitude, pulse rate, and pulse phase are studied using openloop control. The measurements indicate that fluid tabs generate a similar streamwise vortex formation process (and hence display increased mixing) as previously observed in solid-tabbed nozzle flows. In incompressible testing the mixing effectiveness with a pair of pulsed fluid tabs 180u out-of-phase was as good as a twin solid tab nozzle for a control jet flowrate of only 0.5 per cent of the primary (core) jet flow. In preliminary high-speed testing similar benefits of fluid tabs over solid tabs were observed. Further study of pulsed fluid tabs is recommended; they have the attractive performance benefit that they can be easily switched off when not needed and offer increased flexibility as the basis of an optimized active control jet mixing device.

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“…Tabs were initially examined because of their ability to eliminate the screech tone fi-om non-ideally expanded supersonic jets (e.g., Brown, 1989 andSamimy et al, 1993). The first research that analyzed how tabs affect the flow field of a round jet was conducted on a low subsonic jet (Bradbury and Khadem, 1975) and this was followed by work on high subsonic and underexpanded supersonic jets (Ahuja and Brown, 1989). Both of these studies used varying numbers of rectangular shaped tabs, and they both agreed that tabs caused: (1) the potential core of the jet to significantly shorten, (2) the loss of the jet's axisymmetric character, and (3) increased entrainment of ambient air into the jet.…”

Section: Introductionmentioning

confidence: 99%

Mixing and Noise in High Speed Axisymmetric Jets

Samimy¹,

Hileman²,

Caraballo³

2003

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Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searchint the collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestioi AFRL-SR-AR-TR-04-.02JZS]Final Technical Report (15 Nov 99 -31 Dec 02) TITLE AND SUBTITLE Mixing and Noise in High Speed Axisymmetric Jets AUTHOR(S)M.. Samimy, J. Hileman, and E. Caraballo FUNDING NUMBERSF49620-00-1-0023 2307/AX 61102F PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES)Ohio This work investigated noise sources and the effects of passive mixing and noise control schemes using vortex generating tabs on noise sources. It is believed that such information is necessary for jet noise modeling and provides guidance for active control of jets for noise mitigation that will follow. The bulk of this work attempts to correlate instantaneous large-amplitude features of the far acoustic field to the dynamic evolution and interaction of large-scale structures within the mixing-layer of ideally expanded, high-speed, high Reynolds number jets. Such mformation is essential for a better understanding of jet noise sources, and jet aeroacoustic modeling and control. ABSTRACTThis work investigated noise sources and the effects of passive mixing and noise control schemes using vortex generating tabs on noise sources. It is believed that such information is necessary for jet noise modeling and provides guidance for active control of jets for noise mitigation that will follow. The bulk of this work attempts to correlate instantaneous large-amplitude features of the far acoustic field to the dynamic evolution and interaction of large-scale structures within the mixing-layer of ideally expanded, high-speed, high Reynolds number jets. Such information is essential for a better understanding of jet noise sources, and jet aeroacoustic modeling and control.The jet under study had a nozzle exit diameter of 2.54 cm, a Mach number of 1.3, and a Reynolds number of 10*. The jet was operated with and without delta tabs to better vmderstand how these noise reduction devices (when used in a chevron configuration) modify the jet and its noise generation mechanisms. Three cases are examined: a baseline (no-tab) jet, a single delta tab jet, and a dual delta tab jet. Power spectra and average acoustic waveform measurements were made for a variety of azimuthal locations; apparent noise origins were determined with an inline microphone array as well as a 3-D microphone array; and temporally resolved flow visualization was used to examine the dynamic flow structure of the jet's mixing-layer. Both of the microphone arrays are unique in they allow for the determination of the origin of individual acoustic 'events' as opposed to obtaining a time-average soimd generation region and they were both placed at an angle of 30° relative to the downstream jet axis. The development and application of both of these novel arrays are presented. Condit...

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The distortion of a jet by tabs

Cited by 288 publications

References 5 publications

Near Exit Plane Effects Caused by Primary and Primary-Plus-Secondary Tabs

Near Exit Plane Effects Caused by Primary and Primary-Plus-Secondary Tabs

Active flow control of jet mixing using steady and pulsed fluid tabs

Mixing and Noise in High Speed Axisymmetric Jets

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