Role of coherent structures in supersonic impinging jets
IR@NAL: CSIR-National Aerospace Laboratories, Bangalore
View Archive Info| Field | Value | |
| Title |
Role of coherent structures in supersonic impinging jets
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| Creator |
Kumar, Rajan
Wiley, Alex Venkatakrishnan, L Alvi, Farukh |
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| Subject |
Aeronautics (General)
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| Description |
This paper describes the results of a study examining the flow field and acoustic characteristics of a Mach 1.5 ideally expanded supersonic jet impinging on a flat
surface and its control using steady microjets. Emphasis is placed on two conditions of nozzle to plate distances (h/d), of which one corresponds to where the microjet based active flow control is very effective in reducing flow unsteadiness and near-field acoustics and the other has minimal effectiveness. Measurements include unsteady pressures, nearfield acoustics using microphone and particle image velocimetry. The nearfield noise and unsteady pressure spectra at both h/d show discrete high amplitude impinging tones, which in one case (h/d = 4) are significantly reduced with control but in the other case (h/d = 4.5) remain unaffected. The particle image velocimetry measurements, both time-averaged and phase-averaged, were used to better understand the basic characteristics of the impinging jet flow field especially the role of coherent vortical structures in the noise generation and control. The results show that the flow field corresponding to the case of least control
effectiveness comprise well defined, coherent, and symmetrical vortical structures and may require higher levels of microjet pressure supply for noise suppression when compared to the flow field more responsive to control (h/d = 4) which shows less organized, competing (symmetrical and helical) instabilities.
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| Publisher |
American Institute of Physics
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| Date |
2013
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| Type |
Journal Article
PeerReviewed |
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| Format |
application/pdf
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| Identifier |
http://nal-ir.nal.res.in/12240/1/ja550.pdf
Kumar, Rajan and Wiley, Alex and Venkatakrishnan, L and Alvi, Farukh (2013) Role of coherent structures in supersonic impinging jets. Physics of Fluids, 25 . 076101-1. ISSN 1070-6631 |
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| Relation |
http://dx.doi.org/10.1063/1.4811401
http://nal-ir.nal.res.in/12240/ |
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