Journal ArticleDOI
Experiments characterizing nonlinear shear layer dynamics in a supersonic rectangular jet undergoing screech
Steven H. Walker,Flint O. Thomas +1 more
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In this paper, the authors used hot-film probes to measure the instability wave development in the jet shear layers along a constant Mach number ray, and higher-order polyspectral techniques were employed to determine resonant nonlinear phase locking between multiple instability modes.Abstract:
Jet screech is the result of a resonant aeroacoustic feedback loop. In modern high-performance aircraft jet screech has given rise to in-flight sonic fatigue failure of nozzle components. For this reason, jet screech has been the focus of numerous investigations. However, the prediction of screech amplitude has been a very elusive goal. A primary objective of the work to be reported is to experimentally characterize the nonlinear instability wave development in the shear layer of a rectangular supersonic jet undergoing screech. Hot-film probes are used to measure the instability wave development in the jet shear layers along a constant Mach number ray. Higher-order polyspectral techniques are employed to determine resonant nonlinear phase locking between multiple instability modes. A detailed comparison of the “inner loop” hot-film measurements with “outer loop” acoustic measurements is made. Such a comparison reveals the importance of incorporating nonlinear effects into a jet screech amplitude predictio...read more
Citations
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Journal ArticleDOI
Computational aeroacoustics: progress on nonlinear problems of sound generation
Tim Colonius,Sanjiva K. Lele +1 more
TL;DR: A hierarchy of computational approaches that range from semi-empirical schemes that estimate the noise sources using mean-flow and turbulence statistics, to high-fidelity unsteady flow simulations that resolve the sound generation process by direct application of the fundamental conservation principles is discussed in this paper.
Journal ArticleDOI
Supersonic Jet Screech: Half-century from Powell to the Present
TL;DR: A detailed overview of the state of the art in the field of supersonic jet screech can be found in this paper, including a historical perspective, a summary of recent developments and a critical assessment of the current state-of-the-art.
Journal ArticleDOI
Coherent structure in a turbulent jet via a vector implementation of the proper orthogonal decomposition
TL;DR: In this paper, the coherent structure in the near-field of an axisymmetric turbulent jet at a Reynolds number of 3.8 × 10 5 and Mach number of 0.3 is experimentally characterized by a vector implementation of the proper orthogonal decomposition (POD).
Journal ArticleDOI
Screech-tone prediction using upstream-travelling jet modes
TL;DR: In this article, a new prediction approach is proposed where the feedback loop is closed by the upstream-travelling jet modes first discussed in Tam and Hu (J Fluid Mech 201:447-483, 1989) in lieu of the free-stream sound waves.
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A numerical investigation of sound generation in supersonic jet screech
Ted A. Manning,Sanjiva K. Lele +1 more
TL;DR: In this paper, the authors studied the effect of an unsteady shear layer with a single oblique shock on the supersonic jet screech, and concluded that the mechanism for high amplitude screech generation is an unstable modification to the velocity field by the instability waves that allowed the incident shock to refract through the shear layers.
References
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Journal ArticleDOI
Digital Bispectral Analysis and Its Applications to Nonlinear Wave Interactions
Young C. Kim,Edward J. Powers +1 more
TL;DR: The bispectrum, which is an ensemble average of a product of three spectral components, is shown to be a very useful diagnostic tool in experimental studies of nonlinear wave interactions in random media.
Journal ArticleDOI
A note on the relation between temporally-increasing and spatially-increasing disturbances in hydrodynamic stability
TL;DR: In this paper, the frequency and amplification rates for a disturbance growing with respect to time are compared with those of a spatially growing wave having the same wave number, and it is shown that the frequencies are equal to a high order of approximation.
Journal ArticleDOI
On the Mechanism of Choked Jet Noise
TL;DR: In this paper, the authors examined the noise in two-dimensional flow with the aid of a dynamic Schlieren apparatus, verifying the suggested mechanism and showing the similarity to axially symmetric flow where discontinuities in frequency, partly analogous to edge tones, occur.
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The planar turbulent jet
Ephraim Gutmark,Israel Wygnanski +1 more
TL;DR: In this article, hot-wire measurements in a plane incompressible jet are reported, where the flow was found to be self-preserving beyond x/d > 40 and measurements were made up to x/D = 120.
Journal ArticleDOI
A digital method of modeling quadratically nonlinear systems with a general random input
K.I. Kim,E.J. Powers +1 more
TL;DR: Without assuming particular statistics of the input, a practical digital method of estimating linear and quadratic transfer functions of a nonlinear time-invariant system that can be described by Volterra series of up to second order is presented.