A low-dimensional approach to closed-loop control of a Mach 0.6 jet

Simultaneous time-resolved measurements of the near-field hydrodynamic pressure field, 2-component streamwise velocity field, and far-field acoustics are taken for an un-heated, axisymmetric Mach 0.6 jet in co-flow. Synthetic jet actuators placed around the periphery of the nozzle lip provide locali...

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Bibliographic Details
Published in:Experiments in fluids 2013-04, Vol.54 (4), p.1-17, Article 1484
Main Authors: Low, Kerwin R., Berger, Zachary P., Kostka, Stanislav, ElHadidi, Basman, Gogineni, Sivaram, Glauser, Mark N.
Format: Article
Language:English
Subjects:
Acoustics
Aeroacoustics, atmospheric sound
Arrays
Correlation
Engineering
Engineering Fluid Dynamics
Engineering Thermodynamics
Exact sciences and technology
Flow control
Fluid dynamics
Fluid flow
Fluid- and Aerodynamics
Fundamental areas of phenomenology (including applications)
Heat and Mass Transfer
Noise (turbulence generated)
Noise: its effects and control
Physics
Reduction
Research Article
Shear layers
Sound pressure
Topics in Flow Control
Turbulent flows, convection, and heat transfer
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Summary:Simultaneous time-resolved measurements of the near-field hydrodynamic pressure field, 2-component streamwise velocity field, and far-field acoustics are taken for an un-heated, axisymmetric Mach 0.6 jet in co-flow. Synthetic jet actuators placed around the periphery of the nozzle lip provide localized perturbations to the shear layer. The goal of this study was to develop an understanding of how the acoustic nature of the jet responds to unsteady shear layer excitation, and subsequently how this can be used to reduce the far-field noise. Review of the cross-correlations between the most energetic low-order spatial Fourier modes of the pressure and the far-field region reveals that mode 0 has a strong correlation and mode 1 has a weak correlation with the far-field. These modes are emulated with the synthetic jet array and used as drivers of the developing shear layer. In open loop forcing configurations, there is energy transfer among spatial scales, enhanced mixing, a reconfiguration of the low-dimensional spatial structure, and an increase in the overall sound pressure level (OASPL). In the closed loop configuration, changes to these quantities are more subtle but there is a reduction in the overall fluctuating sound pressure level OASPL f by 1.35 dB. It is argued that this reduction is correlated with the closed loop control feeding back the dynamical low-order information measured in the largest noise producing region.
ISSN:0723-4864
1432-1114
DOI:10.1007/s00348-013-1484-8