A Nonlinear PSE-Based Model for Jet Noise

Salgado, Adriana; Agarwal, Anurag; Suponitsky, Victoria; Sandham, Neil D.

doi:10.2514/6.2010-3969

Cited by 3 publications

(1 citation statement)

References 14 publications

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“…18 These mechanisms are the subject of ongoing research, which considers either simplified, kinematic sound-source models [19][20][21] or the coupling of dynamic wavepacket models with an acoustic analogy. [22][23][24][25] The purpose of the work described here is to investigate the limits of the underlying hypotheses in wavepacket models by comparing solutions of the linear Parabolised Stability Equations (PSE) with experimental data for a turbulent subsonic jet previously studied by this group. 10 That work has shown that the axisymmetric and first helical modes of the velocity field correspond to linear wavepackets, close agreement being observed between PSE and experiment for Strouhal numbers ranging from 0.3 to 0.9, and for axial stations ranging from the nozzle exit plane to the end of the potential core of the jet.…”

Section: Introductionmentioning

confidence: 99%

High-frequency wavepackets in turbulent jets

et al. 2017

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Wavepackets obtained as solutions of the flow equations linearised around the mean flow have been shown in recent work to yield good agreement, in terms of amplitude and phase, with those educed from turbulent jets. Compelling agreement has been demonstrated, for the axisymmetric and first helical mode, up to Strouhal numbers close to unity. We here extend the range of validity of wavepacket models to Strouhal number $St=4.0$ and azimuthal wavenumber $m=4$ by comparing solutions of the parabolised stability equations with a well-validated large-eddy simulation of a Mach 0.9 turbulent jet. The results show that the near-nozzle dynamics can be correctly described by the homogeneous linear model, the initial growth rates being accurately predicted for the entire range of frequencies and azimuthal wavenumbers considered. Similarly to the lower-frequency wavepackets reported prior to this work, the high-frequency linear waves deviate from the data downstream of their stabilisation locations, which move progressively upstream as the frequency increases.

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Section: Introductionmentioning

confidence: 99%

High-frequency wavepackets in turbulent jets

et al. 2017

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On the Mach number and temperature dependence of jet noise: Results from a simplified numerical model

Suponitsky

Sandham

Agarwal

2011

Journal of Sound and Vibration

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Parabolized Stability Equations analysis of nonlinear interactions with forced eigenmodes to control subsonic jet instabilities

et al. 2015

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Nonlinear evolution of disturbances in an axisymmetric, high subsonic, high Reynolds number hot jet with forced eigenmodes is studied using the Parabolized Stability Equations (PSE) approach to understand how modes interact with one another. Both frequency and azimuthal harmonic interactions are analyzed by setting up one or two modes at higher initial amplitudes and various phases. While single mode excitation leads to harmonic growth and jet noise amplification, controlling the evolution of a specific mode has been made possible by forcing two modes (m1, n1), (m2, n2), such that the difference in azimuth and in frequency matches the desired “target” mode (m1 − m2, n1 − n2). A careful setup of the initial amplitudes and phases of the forced modes, defined as the “killer” modes, has allowed the minimizing of the initially dominant instability in the near pressure field, as well as its estimated radiated noise with a 15 dB loss. Although an increase of the overall sound pressure has been found in the range of azimuth and frequency analyzed, the present paper reveals the possibility to make the initially dominant instability ineffective acoustically using nonlinear interactions with forced eigenmodes.

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A Nonlinear PSE-Based Model for Jet Noise

Cited by 3 publications

References 14 publications

High-frequency wavepackets in turbulent jets

High-frequency wavepackets in turbulent jets

On the Mach number and temperature dependence of jet noise: Results from a simplified numerical model

Parabolized Stability Equations analysis of nonlinear interactions with forced eigenmodes to control subsonic jet instabilities

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