Journal ArticleDOI
Effect of anisotropic turbulence on aerodynamic noise
M. Goldstein,B. Rosenbaum +1 more
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A model based on Lighthill's theory for predicting aerodynamic noise from a turbulent shear flow is developed in this article, which does not require that the turbulent correlations factor into space and time-dependent parts.Abstract:
A model based on Lighthill's theory for predicting aerodynamic noise from a turbulent shear flow is developed. This model is a generalization of the one developed by Ribner. It does not require that the turbulent correlations factor into space and time-dependent parts. It replaces his assumption of isotropic turbulence by the more realistic one of axisymmetric turbulence. In the course of the analysis, a hierarchy of equations is developed wherein each succeeding equation involves more assumptions than the preceding equation but requires less experimental information for its use. The implications of the model for jet noise are discussed. It is shown that for the particular turbulence data considered anisotropy causes the high-frequency self-noise to be beamed downstream.read more
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Journal ArticleDOI
The sources of jet noise: experimental evidence
TL;DR: In this article, four different approaches are used to determine experimentally the sources of jet mixing noise: spectral and directional information measured by a single microphone in the far field, fine-scale turbulence, large turbulence structures of the jet flow, and a mirror microphone is used to measure the noise source distribution along the lengths of high speed jets.
Journal ArticleDOI
Stochastic approach to noise modeling for free turbulent flows
TL;DR: In this paper, a new approach to noise modeling for free turbulent flows is presented, where the equations governing the sound field are obtained in two steps, the first step consists of treating the mean and turbulent components of the flow while the acoustic perturbations are neglected.
Journal ArticleDOI
Pressure velocity coupling in a subsonic round jet
C. Picard,Joel Delville +1 more
TL;DR: In this article, the radial distribution of velocity within the shear layer of a jet and the longitudinal distribution of pressure surrounding a jet are performed using two statistical approaches (proper orthogonal decomposition, POD and linear stochastic estimation, LSE).
Journal ArticleDOI
Jet Noise: Acoustic Analogy informed by Large Eddy Simulation
Sergey A. Karabasov,Mohammed Afsar,Tom Hynes,Ann P. Dowling,W. A. McMullan,C.D. Pokora,Gary J. Page,James J. McGuirk +7 more
TL;DR: In this article, a hybrid approach to the development of a hybrid prediction methodology for jet noise is described, where a Gaussian function model for the two-point cross correlation of the fourth-order velocity fluctuations in the acoustic source is presented.
Journal ArticleDOI
Aircraft noise reduction technologies: A bibliographic review
TL;DR: In this article, a bibliographical review of the main technologies employed for the mitigation of aircraft noise is presented, according to a component-based approach, analytical and semi-empirical models of the aeroacoustic mechanisms involved in the noise generation from airframe and engine components are presented as a key element of the noise reduction technology.