Developments in jet noise modelling—theoretical predictions and comparisons with measured data

Tester, Brian J.; Morfey, C. L.

doi:10.1016/0022-460x(76)90819-1

Cited by 124 publications

(66 citation statements)

References 15 publications

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“…Adequate agreement between the exact source directivity and a high-frequency approximation for Strouhal numbers as small as one has been demonstrated in some limited circumstances by Tester and Morfey [7] using a ray-theory solution for polar angles outside the zone of silence of a round jet and by Scott [8] for a two-dimensional isothermal flow with a piecewise constant mean shear. The primary objective of the present paper is to determine the relative success of the above three high-frequency approximations for parallel round jets by comparing them to the exact order-one frequency solution over a wide range Strouhal numbers and far-field observation angles.…”

Section: Nasa/cr---2003-212089mentioning

confidence: 81%

On the applicability of high-frequency approximations to Lilley's equation

Wundrow

Khavaran²

2004

Journal of Sound and Vibration

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Section: Nasa/cr---2003-212089mentioning

confidence: 81%

On the applicability of high-frequency approximations to Lilley's equation

Wundrow

Khavaran²

2004

Journal of Sound and Vibration

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“…There is no cone of silence since the acoustic wavelength is an order of magnitude larger than the shear layer thickness (Tester & Morfey 1976).…”

Section: Extrapolation Of the Acoustic Fieldmentioning

confidence: 99%

Nonlinear mechanisms of sound generation in a perturbed parallel jet flow

Sandham

Morfey

2006

J. Fluid Mech.

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An initial value problem with relevance to jet noise is investigated. A plane parallel jet flow is subjected to a spatially localized initial disturbance and is then left to evolve according to the two-dimensional compressible Navier-Stokes equations. The hydrodynamic response is in the form of a convecting vortex packet. The Ffowcs WilliamsHawkings approach is formulated in the time domain and used to extrapolate from the simulated near field to the acoustic far field. The predominant downstream sound radiation comes from an early stage of nonlinear development of the vortex packet. Two simplified models to account for the radiation are introduced, based on nonlinear mode interactions on a prescribed base flow. The first uses two sets of linearized Euler equations, coupled via the inviscid Lilley-Goldstein acoustic analogy. This formulation separates the linear sound field from the sound field driven by nonlinear interactions; qualitative agreement of the latter with the Navier-Stokes computations demonstrates the importance of nonlinear interactions. The second model uses combinations of linear inviscid eigenmodes to drive the sound field, which allows extraction of the dominant mode interactions responsible for the observed radiation pattern. The results indicate that a difference-wavenumber nonlinear interaction mechanism dominates sound radiation from subsonic instability modes in shear flows.

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“…Among the variants of the original theory, Lilley's approach appears to have attracted the largest number of followers (e.g. Tester & Morfey 1976;Khavaran et al 1994;Morris & Farassat 2002;Goldstein 2003;Hunter & Thomas 2003;and others). Schlinker (1975) and Laufer, Schlinker & Kaplan (1976) appear to be the first to propose an alternative jet noise source model.…”

Section: Introductionmentioning

confidence: 99%

The Sources of Jet Noise: Experimental Evidence

Tam¹,

Viswanathan

Ahuja

et al. 2007

13th AIAA/CEAS Aeroacoustics Conference (28th AIAA Aeroacoustics Conference)

106

174

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The primary objective of this investigation is to determine experimentally the sources of jet mixing noise. In the present study, four different approaches are used. It is reasonable to assume that the characteristics of the noise sources are imprinted on their radiation fields. Under this assumption, it becomes possible to analyse the characteristics of the far-field sound and then infer back to the characteristics of the sources. The first approach is to make use of the spectral and directional information measured by a single microphone in the far field. A detailed analysis of a large collection of far-field noise data has been carried out. The purpose is to identify special characteristics that can be linked directly to those of the sources. The second approach is to measure the coherence of the sound field using two microphones. The autocorrelations and cross-correlations of these measurements offer not only valuable information on the spatial structure of the noise field in the radial and polar angle directions, but also on the sources inside the jet. The third approach involves measuring the correlation between turbulence fluctuations inside a jet and the radiated noise in the far field. This is the most direct and unambiguous way of identifying the sources of jet noise. In the fourth approach, a mirror microphone is used to measure the noise source distribution along the lengths of high-speed jets. Features and trends observed in noise source strength distributions are expected to shed light on the source mechanisms. It will be shown that all four types of data indicate clearly the existence of two distinct noise sources in jets. One source of noise is the fine-scale turbulence and the other source is the large turbulence structures of the jet flow. Some of the salient features of the sound field associated with the two noise sources are reported in this paper.

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Developments in jet noise modelling—theoretical predictions and comparisons with measured data

Cited by 124 publications

References 15 publications

On the applicability of high-frequency approximations to Lilley's equation

On the applicability of high-frequency approximations to Lilley's equation

Nonlinear mechanisms of sound generation in a perturbed parallel jet flow

The Sources of Jet Noise: Experimental Evidence

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