A Model for Jet-surface Interaction Noise Using Physically Realizable Upstream Turbulence Conditions PDF Download
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Author: Mohammed Z. Afsar
Publisher:
ISBN:
Category :
Languages : en
Pages : 22
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Author: Mohammed Z. Afsar
Publisher:
ISBN:
Category :
Languages : en
Pages : 22
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Author: National Aeronautics and Space Administration (NASA)
Publisher: Createspace Independent Publishing Platform
ISBN: 9781719396714
Category :
Languages : en
Pages : 30
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Book Description
The process of developing an empirical model for jet-surface interaction noise is described and the resulting model evaluated. Jet-surface interaction noise is generated when the high-speed engine exhaust from modern tightly integrated or conventional high-bypass ratio engine aircraft strikes or flows over the airframe surfaces. An empirical model based on an existing experimental database is developed for use in preliminary design system level studies where computation speed and range of configurations is valued over absolute accuracy to select the most promising (or eliminate the worst) possible designs. The model developed assumes that the jet-surface interaction noise spectra can be separated from the jet mixing noise and described as a parabolic function with three coefficients: peak amplitude, spectral width, and peak frequency. These coefficients are fit to functions of surface length and distance from the jet lipline to form a characteristic spectra which is then adjusted for changes in jet velocity and/or observer angle using scaling laws from published theoretical and experimental work. The resulting model is then evaluated for its ability to reproduce the characteristic spectra and then for reproducing spectra measured at other jet velocities and observer angles; successes and limitations are discussed considering the complexity of the jet-surface interaction noise versus the desire for a model that is simple to implement and quick to execute. Brown, Clifford A. Glenn Research Center AIRCRAFT DESIGN; NOISE PREDICTION; COMPUTERIZED SIMULATION; ACOUSTIC SIMULATION; AEROACOUSTICS; AERODYNAMIC NOISE; JET AIRCRAFT NOISE; SURFACE REACTIONS; COMPUTATIONAL AEROACOUSTICS; COMPUTATIONAL FLUID DYNAMICS; NOISE REDUCTION; NOISE MEASUREMENT; FLUID FLOW; ENGINE AIRFRAME INTEGRATION; COEFFICIENTS; FREQUENCIES; AIRFRAMES; TURBULENCE; TRAILING EDGES; NOISE SPECTRA; JET MIXING FLOW
Author: Roberto Camussi
Publisher: Springer Science & Business Media
ISBN: 3709114586
Category : Technology & Engineering
Languages : en
Pages : 453
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Book Description
The articles in this volume present the state-of-the-art in noise prediction, modeling and measurement. The articles are partially based on class notes provided during the course `Noise sources in turbulent shear flows', given at CISM on April 2011. The first part contains general concepts of aero acoustics, including vortex sound theory and acoustic analogies, in the second part particular emphasis is put into arguments of interest for engineers and relevant for aircraft design: jet noise, airfoil broadband noise, boundary layer noise (including interior noise and its control) and the concept of noise sources, their theoretical modeling and identification in turbulent lows. All these arguments are treated extensively with the inclusion of many practical examples and references to engineering applications.
Author: Clifford Alan Brown
Publisher:
ISBN:
Category :
Languages : en
Pages : 24
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Author: Harvey H. Hubbard
Publisher:
ISBN:
Category : Aerodynamic noise
Languages : en
Pages : 620
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Author: Martin Frederick Dawson
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Author: National Aeronautics and Space Administration (NASA)
Publisher: Createspace Independent Publishing Platform
ISBN: 9781719503693
Category :
Languages : en
Pages : 58
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Book Description
Jet flows interacting with nearby surfaces exhibit a complex behavior in which acoustic and aerodynamic characteristics are altered. The physical understanding and prediction of these characteristics are essential to designing future low noise aircraft. A new approach is created for predicting scattered jet mixing noise that utilizes an acoustic analogy and steady Reynolds-averaged Navier-Stokes solutions. A tailored Green's function accounts for the propagation of mixing noise about the air-frame and is calculated numerically using a newly developed ray tracing method. The steady aerodynamic statistics, associated unsteady sound source, and acoustic intensity are examined as jet conditions are varied about a large at plate. A non-dimensional number is proposed to estimate the effect of the aerodynamic noise source relative to jet operating condition and airframe position. The steady Reynolds-averaged Navier-Stokes solutions, acoustic analogy, tailored Green's function, non- dimensional number, and predicted noise are validated with a wide variety of measurements. The combination of the developed theory, ray tracing method, and careful implementation in a stand-alone computer program result in an approach that is more first principles oriented than alternatives, computationally efficient, and captures the relevant physics of fluid-structure interaction. Miller, Steven A. Langley Research Center JET AIRCRAFT NOISE; JET MIXING FLOW; TURBULENT MIXING; AEROACOUSTICS; RAY TRACING; PREDICTION ANALYSIS TECHNIQUES; AIRFRAMES; GREEN'S FUNCTIONS; COMPUTER PROGRAMS; ANALOGIES; AERODYNAMIC CHARACTERISTICS; LOW NOISE; REYNOLDS EQUATION; REYNOLDS AVERAGING
Author:
Publisher:
ISBN:
Category : Aeronautics
Languages : en
Pages : 662
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Book Description
Lists citations with abstracts for aerospace related reports obtained from world wide sources and announces documents that have recently been entered into the NASA Scientific and Technical Information Database.
Author: J. L. McGreevy
Publisher:
ISBN:
Category :
Languages : en
Pages : 38
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Author: George P. Succi
Publisher:
ISBN:
Category : Acoustic models
Languages : en
Pages : 52
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