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Investigation of tone generation in ideally expanded supersonic planar impinging jets using large-eddy simulation

Gojon, Romain and Bogey, Christophe and Marsden, Olivier Investigation of tone generation in ideally expanded supersonic planar impinging jets using large-eddy simulation. (2016) Journal of Fluid Mechanics, 808. 90-115. ISSN 0022-1120

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Official URL: http://dx.doi.org/10.1017/jfm.2016.628

Abstract

The generation of tones in a supersonic planar jet impinging on a flat plate normally has been investigated by performing compressible large-eddy simulations using low-dissipation and low-dispersion finite differences. At the exit of a straight nozzle of height $h$ , the jet is ideally expanded, and has a Mach number of 1.28 and a Reynolds number of 50000. Four distances between the nozzle and the plate between 3.94h and 9.1h have been considered. Flow snapshots and mean velocity fields are first presented. The variations of turbulence intensities and of the convection velocity in the jet shear layers are then examined. The properties of the jet near fields are subsequently described, in particular by applying Fourier decomposition to the pressure fields. Several coexisting tones appear to be generated by aeroacoustic feedback loops establishing between the nozzle lip and the flat plate, which also lead to the presence of hydrodynamic–acoustic standing waves. The tone frequencies are consistent with those given by the aeroacoustic feedback model and with measurements for high-aspect-ratio rectangular jets. The jet oscillation modes at these frequencies are characterized, and found to agree with experimental data. Their symmetric or antisymmetric natures are shown to be well predicted by a wave analysis carried out using a vortex sheet model of the jet, providing the allowable frequency ranges for the upstream-propagating acoustic waves. Thus, it is possible, for an ideally expanded impinging planar jet to predict both the frequencies of the tones and the symmetric or antisymmetric nature of the corresponding oscillation modes by combining the aeroacoustic feedback model and the wave analysis.

Item Type:Article
Audience (journal):International peer-reviewed journal
Uncontrolled Keywords:
Institution:French research institutions > Centre National de la Recherche Scientifique - CNRS (FRANCE)
Other partners > Institut National des Sciences Appliquées de Lyon - INSA (FRANCE)
Other partners > Université Claude Bernard-Lyon I - UCBL (FRANCE)
Other partners > Ecole Centrale de Lyon (FRANCE)
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Deposited By: Romain GOJON
Deposited On:13 Dec 2017 13:53

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