Azimuthal Source Noncompactness and Mode Coupling in Sound Radiation from High-Speed Axisymmetric Jets

Goldstein, M. E.; Leib, S. J.

doi:10.2514/1.j057276

Cited by 3 publications

(3 citation statements)

References 36 publications

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“…The above approaches still remain the current state-of-art for low-order prediction models based on the acoustic analogy models (see Ref. 24). Note that while these models rely on accurate RANS mean flow solutions (which themselves are based on turbulence models) the centerline mean flow distribution is usually accurately predicted compared to particle-image velocimetry (PIV) data, with closest agreement being at the end of jet potential core (see Karabasov et al 22 and §.3).…”

Section: Introductionmentioning

confidence: 99%

Effect of non-parallel mean flow on the acoustic spectrum of heated supersonic jets: Explanation of “jet quietening”

2019

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Noise measurements of heated axisymmetric jets at fixed supersonic acoustic Mach number indicate that the acoustic spectrum reduces when the temperature ratio increases. The 'spectral quietening' effect has been observed both experimentally and computationally using Large Eddy Simulations (LES). It was explained by Afsar et al. (M. Z. Afsar and M. E. Goldstein & A. M. Fagan AIAAJ., Vol. 49, p. 2522, 2011) through the cancellation introduced by enthalpy flux/momentum flux coupling term using the generalized acoustic analogy formulation. But the parallel flow assumption is known to give inaccurate predictions at high jet speeds. In this paper we therefore extend the non-parallel flow asymptotic theory of Goldstein et al.

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Section: Introductionmentioning

confidence: 99%

Effect of non-parallel mean flow on the acoustic spectrum of heated supersonic jets: Explanation of “jet quietening”

2019

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“…The source amplitude considered in Actran TM is defined with respect to the pressure (variable AMPLITUDE_TYPE set to P). Note that this correction holds for a three dimensional space, if a bidimensional configuration was studied, the amplitude correction factor, equation (32), should be multiplied by π. The implementation of this background mean flow fields reformulation has successfully been verified for a sheared and stratified propagation medium [60].…”

Section: J O U R N a L P R E -P R O O Fmentioning

confidence: 99%

Noise predictions of a Mach 0.9 round jet using tailored adjoint Green’s functions

Spieser

Bogey

Bailly

2023

Journal of Sound and Vibration

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“…It is well known [22] that Γ * k,l (y + η|x; ω) can be approximated by taking advantage of the scale disparity between the mean flow and turbulence relative to the acoustic wavelength λ a in the correlation volume V(η) of integral (2.2) (but see [28] for an analysis of the effects of azimuthal non-compactness). In an asymptotic sense, the ALEE solution that enters Γ * k,l via (2.5) will only contribute to the integral over O(|η|) distances in (2.2) when the mean flow length scales that determine the coefficients (and, therefore, the solution structure) of (2.7) are of the same order as the turbulence correlation lengths in their respective directions.…”

Section: Asymptotic Analysis Within the Generalized Acoustic Analogymentioning

confidence: 99%

Modelling and prediction of the peak-radiated sound in subsonic axisymmetric air jets using acoustic analogy-based asymptotic analysis

Afsar

Sescu

Leib

2019

Phil. Trans. R. Soc. A.

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This paper uses asymptotic analysis within the generalized acoustic analogy formulation (Goldstein. JFM 488, pp. 315-333, 2003) to develop a noise prediction model for the peak sound of axisymmetric round jets at subsonic acoustic Mach numbers (M a). The analogy shows that the exact formula for the acoustic pressure is given by a convolution product of a propagator tensor (determined by the vector Green's function of the adjoint linearized Euler equations for a given jet mean flow) and a generalized source term representing the jet turbulence field.Using a low frequency/small spread rate asymptotic expansion of the propagator, mean flow nonparallelism enters the lowest order Green's function solution via the streamwise component of the mean flow advection vector in a hyperbolic partial differential equation (PDE). We then address the predictive capability of the solution to this PDE when used in the analogy through first-of-its-kind numerical calculations when an experimentally-verified model of the turbulence source structure is used together with Reynolds-averaged Navier Stokes solutions for the jet mean flow. Our noise predictions show a reasonable level of accuracy in the peak noise direction at M a = 0.9, for Strouhal number up to about 0.6, and at M a = 0.5 using modified source coefficients. Possible reasons for this are discussed. Moreover, the prediction range can be extended beyond unity Strouhal number by using an approximate composite asymptotic formula for the vector Green's function that reduces to the locally parallel flow limit at high frequencies.arXiv:1907.05503v1 [physics.flu-dyn]

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Azimuthal Source Noncompactness and Mode Coupling in Sound Radiation from High-Speed Axisymmetric Jets

Cited by 3 publications

References 36 publications

Effect of non-parallel mean flow on the acoustic spectrum of heated supersonic jets: Explanation of “jet quietening”

Effect of non-parallel mean flow on the acoustic spectrum of heated supersonic jets: Explanation of “jet quietening”

Noise predictions of a Mach 0.9 round jet using tailored adjoint Green’s functions

Modelling and prediction of the peak-radiated sound in subsonic axisymmetric air jets using acoustic analogy-based asymptotic analysis

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