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Showing 1 to 10 of 10 for “"jet noise reduction"”.
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Perturbation Solution of Air-Water Mixture for Jet Noise Reduction
<p>This work investigates passive jet-noise mitigation using externally positioned air–water curtains that attenuate radiated sound without altering the underlying jet dynamics. Two classes of multiphase media are examined: a gaseous carrier phase containing dispersed liquid droplets, and a liquid …
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Resolvent-based framework for jet noise reduction of a low bypass ratio coannular nozzle
Submission published under a 24 month embargo labeled 'U of I Access', the embargo will last until 2025-08-01
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Propulsion system concepts for silent aircraft
The noise emitted by commercial aircraft is a major inhibitor of the growth of commercial air transport and is a critical environmental issue in air transportation. A functionally-silent aircraft is envisioned to achieve a step change in airframe and propulsion system noise reduction (30 EPNdB). …
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Aeroacoustics of Supersonic Jet Interacting with Solid Surfaces and its Suppression
<p>The noise generated by supersonic jet is of primary interest in the high-speed flight. In several flight conditions jet exhaust of the propulsion system interacts with solid surfaces. For example, jet impingement on ground for a rocket lift-off, or interactions influenced by the integration of …
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Space-time Description of Supersonic Jets with Thermal Non-uniformity
The supersonic jet plumes that exhaust from the engines of tactical aircraft produce intense noise signatures that expose the Navy personnel working on the deck of aircraft carriers to dangerously high levels of noise that often results in hearing damage. Reducing the noise radiated by these …
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Active Control of Coherent Structures in an Axisymmetric Jet
… is to develop high-fidelity simulation model for jet noise control predictions and quantify the sound reduction when an external source frequency mode excitation is imposed on the jet flow. Whereas passive approaches using mixing devices, such as chevrons, have been shown to reduce low-frequency …
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Adjoint-based control of turbulent jet noise
Noise is an important factor in certifying an airplane and more restrictive noise regulations have demanded the design of quieter aircraft, with much of the emphasis focused on lower jet-noise emission. Previous passive and active noise-reduction strategies required parametric experiments or …
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The Effect of Thermal Non-Uniformity on Coherent Structures in Supersonic Free Jets
Supersonic jet exhaust plumes produce noise in jet engines, which has been a problem in the aerospace field. Researchers are working on ways to reduce this turbulent mixing noise, with little modification to the engine and nozzle. Prior work has shown that total temperature non-uniformity is a …
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Investigation of Noise Sources in Three-Stream Jets using Turbulence Characteristics
Key areas of noise sources are investigated through comparison of eddy convection velocity and turbulence measurements in three-stream nozzles. A Time-Resolved Doppler Global Velocimetry (TR-DGV) Instrument was applied to the Nozzle Acoustic Test Rig (NATR) at NASA's Aero-Acoustic Propulsion Lab …
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Reducing noise from supersonic jets using linear feedback control informed by resolvent analysis
Submission published under a 24 month embargo labeled 'U of I Access', the embargo will last until 2027-05-01