Analysis of the hypersonic cross-flow instability with experimental wavenumber distributions

Yates, Harrison B.; Tufts, Matthew W.; Juliano, Thomas J.

doi:10.1017/jfm.2019.864

Cited by 13 publications

(3 citation statements)

References 30 publications

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“…a scalogram, using a wavelet transformation. Yates, Tufts & Juliano (2020) have recently utilized this technique to identify localized features of stationary cross-flow vortices over a hypersonic cone. In addition to its localized nature, perturbations in the wavepacket are also qualitatively different in the leading and trailing regions, which precludes statistical stationarity (in time) of the signal.…”

Section: Three-dimensional Transition Mechanisms In Cooled Hblsmentioning

confidence: 99%

Instabilities and transition in cooled wall hypersonic boundary layers

Nair

Gaitonde

2021

J. Fluid Mech.

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Section: Three-dimensional Transition Mechanisms In Cooled Hblsmentioning

confidence: 99%

Instabilities and transition in cooled wall hypersonic boundary layers

Nair

Gaitonde

2021

J. Fluid Mech.

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“…The CWT and the GMWs were used to analyze the time series of the sand bed height fluctuations in separate streamwise positions. Yates et al [55] of stationary cross-flow waves from experimental data. The parameters of the Morse wavelet, similar to other studies presented, were 3 for the value of gamma and 60 for the timebandwidth product.…”

Section: ) Fluid Dynamicsmentioning

confidence: 99%

Applications of the Generalized Morse Wavelets: A Review

et al. 2023

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The study of signals, processes, and systems has motivated the development of different representations that can be used to analyze and understand them. Classical ways of studying the behavior of signals are the time domain and frequency domain representations. For the analysis of non-stationary signals, time-frequency representations have become an essential tool to understand how the frequency content of signals changes with time. A common time-frequency technique employed in the literature is the wavelet transform. Nevertheless, selecting an adequate mother wavelet to perform the wavelet transform has become challenging due to the diverse available wavelet families. This paper reviews the applications and uses of a particular class of wavelet basis known as the Generalized Morse Wavelets. This class of wavelet family provides a systematic framework to choose and generate a wavelet for general-purpose use. This study reviews the application of Generalized Morse Wavelets in biomedical engineering, dynamical systems analysis, electrical engineering, geophysics, and communication systems. Moreover, the parameters of the Generalized Morse Wavelets used in each study are presented. The results of this study reveal that Generalized Morse Wavelets have proven helpful in studying signals, systems, and processes in areas ranging from biomedical engineering to geophysics. Nonetheless, the parameters of the Generalized Morse Wavelets are yet to be chosen through a rigorous methodology and argumentation. Therefore, there is an opportunity to generate methods for selecting the parameters of the Generalized Morse Wavelets based on the characteristics of the signals, systems, or processes under research.INDEX TERMS Generalized Morse wavelets, mother wavelet selection, continuous wavelet transform, applications, time-frequency analysis.

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“…Spectral analyses of such signals are best accomplished by a time-frequency approach, e.g., a scalogram, using a wavelet transformation. Yates et al 50 have recently utilized this technique to identify localized features of stationary cross-flow vortices over a hypersonic cone. In addition to its localized nature, perturbations in the wavepacket are also qualitatively different in the leading and trailing regions, which precludes statistical stationarity (in time) of the signal.…”

Section: V2 Waveform Evolution and Spectramentioning

confidence: 99%

Instability characteristics of cooled hypersonic boundary layers

Unnikrishnan

Gaitonde

2020

AIAA Scitech 2020 Forum

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Wall cooling has substantial qualitative and quantitative effects on the development of instabilities and subsequent transition processes in hypersonic boundary layers (HBLs). A sequence of linear stability theory, two-dimensional and non-linear three-dimensional direct numerical simulations is used to analyze Mach 6 boundary layers, with wall temperatures ranging from near-adiabatic to highly cooled conditions, where the second-mode instability is accompanied by radiation of energy. Decomposition of linear stability modes into their fluid-thermodynamic (acoustic, vortical and thermal) components shows that this radiation comprises both acoustic as well as vortical waves. Furthermore, in these cases, 2D simulations show that the conventional "trapped" nature of second-mode instability is ruptured. A quantitative analysis indicates that although the energy efflux of both acoustic and vortical components increases with wall-cooling, the destabilization effect is much stronger and no significant abatement of pressure perturbations is realized. The direct impact of these mechanisms on the transition process itself is examined with high-fidelity simulations of three-dimensional second-mode wavepacket propagation. In the near-adiabatic HBL, the wavepacket remains trapped within the boundary layer and attenuates outside the region of linear instability. However, wavepackets in the cooled-wall HBLs amplify and display nonlinear distortion, and transition more rapidly. The structure of the wavepacket also displays different behavior; moderately-cooled walls show bifurcation into a leading turbulent head region and a trailing harmonic region, while highly-cooled wall cases display lower convection speeds and significant wavepacket elongation, with intermittent spurts of turbulence in the wake of the head region. This elongation effect is associated with a weakening of the lateral jet mechanism due to the breakdown of spanwise coherent structures. These features have a direct impact on wall loading, including skin friction and heat transfer. In moderately cooled-walls, the spatially-localized wall loading is similar to those in near-adiabatic walls, with dominant impact due to coherent structures in the leading turbulent head region. In highly-cooled walls, the elongated near-wall streaks in the wake region of the wavepacket result in more than twice as large levels of skin friction and heat transfer over a sustained period of time.

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Analysis of the hypersonic cross-flow instability with experimental wavenumber distributions

Cited by 13 publications

References 30 publications

Instabilities and transition in cooled wall hypersonic boundary layers

Instabilities and transition in cooled wall hypersonic boundary layers

Applications of the Generalized Morse Wavelets: A Review

Instability characteristics of cooled hypersonic boundary layers

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