Role of coherent structures in supersonic impinging jet noise and its control

Kumar , R and Venkatakrishnan, L and Wiley, Alex and Alvi, Farukh (2010) Role of coherent structures in supersonic impinging jet noise and its control. In: 16th AIAA/CEAS Aeroacoustics Conference, 7-9 Jun 2010, Stockholm, Sweden.

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Abstract

This paper describes the results of a study examining the flow and acoustic characteristics of a Mach 1.5 ideally expanded supersonic jet impinging on a flat surface and its control using 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 with minimal effectiveness. Measurements include unsteady pressures using fast response pressure transducers, near-field acoustics using microphone and particle image velocimetry (PIV). The near-field 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 PIV measurements, both time-averaged and phase-averaged were used to understand the basic characteristics of an impinging jet flow field and the role of coherent vortical structures in the noise generation and suppression. The results show that the flow field corresponding to the case of least control effectiveness comprise well defined, coherent and symmetrical vortical structures and will require higher levels of microjet pressure supply for noise suppression.

Item Type:	Conference or Workshop Item (Paper)
Additional Information:	Copyright to this document belongs to M/s. American Institute of Aeronautics and Astronautics.
Uncontrolled Keywords:	Aeroacoustics;Supersonic impinging jet;Microjet pressure; Particle image velocimetry (PIV)
Subjects:	AERONAUTICS > Aeronautics (General) AERONAUTICS > Aerodynamics
Depositing User:	Ms. Alphones Mary
Date Deposited:	06 Nov 2013 04:46
Last Modified:	06 Nov 2013 04:46
URI:	http://nal-ir.nal.res.in/id/eprint/11837

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