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Showing 1 to 20 of 49 for “"Jet Noise"”.
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Installed jet noise
… the prediction and reduction of installed jet noise, combining both analytical and experimental techniques. In the prediction part, it starts with formulating a low-order but robust isolated jet noise prediction model, based on which a remarkably fast code with pre-informed data is …
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Jet Noise Control by Adjoint-Based Optimization
… control actuation in order to reduce the noise radiated by a randomly excited two-dimensional mixing layer, which serves as near-nozzle model of a jet. The initial-vorticity-thickness Reynolds number is 500, and the free stream Mach numbers are 0.9 and 0.2. Controls are implemented into …
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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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A contribution to the jet noise installation problem
… of this thesis is to understand and predict jet noise installation effects for engines mounted below aircraft wings. This is done through a variety of empirical, analytical and computational methods. Aspects of the jet source are examined and a jet source model, suitable for determining …
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Spinning modes in orderly jet structure and jet noise
The structural response of a subsonic turbulent jet to controlled forcing has been investigated both theoretically and experimentally. An experimental study has been carried out in which a model jet was subjected to acoustic excitation in the form of circumferential modes of azimuthal wavenumber …
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Very near-nozzle shear-layer turbulence and jet noise
Jet noise is sensitive to nozzle configurations and most current aircraft operate close to Federal Aviation Administration (FAA) and other noise restriction levels, with more stringent requirements expected in the future. At the current time, however, prediction capabilities lack the fidelity to …
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Design of a shock tube for jet noise research
Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 1996.
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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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The reduction of supersonic jet noise using pulsed microjet injection
… concerned with the active control of supersonic jet noise using pulsed microjet injection at the nozzle exit. Experimental investigations were carried out using this control method on an ideally expanded Mach 1.8 jet operating at 900, 1300 and 1700'F. Six Bosch fuel injectors were modified and …
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Development & Validation of the Acoustic Analogy Code for Jet Noise Predictions
… to predict acoustic radiation from turbulent jets is briefly discussed.</p>
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Coalescence of nonlinear acoustic waves, with application to supersonic jet noise
… and crackle close to a lab-scale, Mach 3 jet flow in prior studies, which contradicted theoretical predictions for that jet. A numerical model based on the Khokhlov–Zabolotskaya–Kuznetsov (KZK) nonlinear wave equation is developed to demonstrate that coalescence leads to increased waveform …
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Stability, LES, and Resolvent Analysis of Thermally Non-uniform Supersonic Jet Noise
For decades noise-induced hearing loss has been a concern of the Department of Defense (DoD). My research investigates noise generation and dispersion in supersonic jets and focuses on the fluid-dynamic regime typical of high-performance turbojet and turbofan engines. The goal of my research is to …
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The Analysis and Prediction of Jet Flow and Jet Noise about Airframe Surfaces
Aircraft noise mitigation has been an ongoing challenge for the aeronautics research community. In response to this challenge, aircraft concepts have been developed in which the propulsion system is integrated with the airframe to shield the noise from the observer. These concepts exhibit …
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A statistical jet-noise model based on the acoustic analogy and a RANS solution
We introduce a hybrid model for the evaluation of jet noise. The model uses the information from a solution of the Reynolds-averaged Navier-Stokes equations (RANS). It evaluates the jet-noise power spectral density (PSD) in the quiescent region outside the turbulent jet. It includes the following …
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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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The Linearized Euler Equations for Predicting Supersonic Jet Noise of a Rectangular Jet Using OpenFOAM
… the acoustics of a heated supersonic rectangular jet. The rectangular jet (RJET) results were compared against experimental data.</p> <p>The results from this work show that OpenFOAM can be used as an effective platform to develop CAA specific solvers. The leeFoam solver successfully predicted …
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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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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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