Acoustic Waves from a Supersonic Jet Impinging on an Inclined Flat Plate

2010 ◽  
Author(s):  
Taku Nonomura ◽  
Yoshinori Goto ◽  
Kozo Fujii
Keyword(s):  
Flat Plate ◽  
Acoustic Waves ◽  
Supersonic Jet

scholarly journals Feedback loop and upwind-propagating waves in ideally expanded supersonic impinging round jets

2017 ◽  
Vol 823 ◽  
pp. 562-591 ◽  
Author(s):  
Christophe Bogey ◽  
Romain Gojon
Keyword(s):  
Flat Plate ◽  
Acoustic Waves ◽  
Feedback Loop ◽  
Supersonic Jet ◽  
Vortex Sheet ◽  
Impinging Jets ◽  
Loop Model ◽  
Turbulent Structures ◽  
Fourier Decomposition ◽  
Pressure Fields

The aeroacoustic feedback loop establishing in a supersonic round jet impinging on a flat plate normally has been investigated by combining compressible large-eddy simulations and modelling of that loop. At the exit of a straight pipe nozzle of radius $r_{0}$, the jet is ideally expanded, and has a Mach number of 1.5 and a Reynolds number of $6\times 10^{4}$. Four distances between the nozzle exit and the flat plate, equal to $6r_{0}$, $8r_{0}$, $10r_{0}$ and $12r_{0}$, have been considered. In this way, the variations of the convection velocity of the shear-layer turbulent structures according to the nozzle-to-plate distance are shown. In the spectra obtained inside and outside of the flow near the nozzle, several tones emerge at Strouhal numbers in agreement with measurements in the literature. At these frequencies, by applying Fourier decomposition to the pressure fields, hydrodynamic-acoustic standing waves containing a whole number of cells between the nozzle and the plate and axisymmetric or helical jet oscillations are found. The tone frequencies and the mode numbers inferred from the standing-wave patterns are in line with the classical feedback-loop model, in which the loop is closed by acoustic waves outside the jet. The axisymmetric or helical nature of the jet oscillations at the tone frequencies is also consistent with a wave analysis using a jet vortex-sheet model, providing the allowable frequency ranges for the upstream-propagating acoustic wave modes of the jet. In particular, the tones are located on the part of the dispersion relations of the modes where these waves have phase and group velocities close to the ambient speed of sound. Based on the observation of the pressure fields and on frequency–wavenumber spectra on the jet axis and in the shear layers, such waves are identified inside the present jets, for the first time to the best of our knowledge, for a supersonic jet flow. This study thus suggests that the feedback loop in ideally expanded impinging jets is completed by these waves.

Computational Aeroacoustic Analysis of Overexpanded Supersonic Jet Impingement on a Flat Plate With/Without Hole

2007 ◽  
Author(s):  
Soshi Kawai ◽  
Seiji Tsutsumi ◽  
Ryoji Takaki ◽  
Kozo Fujii
Keyword(s):  
Shear Layer ◽  
Flat Plate ◽  
Acoustic Waves ◽  
Near Field ◽  
Supersonic Jet ◽  
Jet Impingement ◽  
Wave Radiation ◽  
Shock Cell ◽  
Mach Wave ◽  
Source Power

Aeroacoustic mechanisms of an axisymmetric over-expanded supersonic jet impinging on a flat plate with and without hole are numerically investigated. High-order weighted compact nonlinear scheme is used to simulate the unsteady flow including shock waves and sound radiation in the near field of the jet. Analyses of unsteady flowfield and related near-sound field reasonably identify three major noise generation mechanisms, that is, noises from Mach wave, shock cell-shear layer interaction and small fluctuations of jet shear layer. Especially, intense noise radiation in the form of Mach waves and its reflection at the plate predominates the noises from the other two finer sources. The simulated distributions of sound source power and its frequency along the jet axis qualitatively well coincide with typical experimental data used in NASA SP-8072. Similar sound pressure spectrum shape is obtained both the cases of flat plate with and without hole, but the case of without hole shows higher SPL by several dB than that of with hole due to the stronger Mach wave radiation. Aeroacoustic flowfield is drastically affected by the Reynolds number because the jet shear layer instability directly causes the strength of acoustic waves.

scholarly journals Акустические характеристики автоколебательного процесса, возникающего при взаимодействии сверхзвуковой недорасширенной струи с цилиндрической полостью

2020 ◽  
Vol 90 (5) ◽  
pp. 733
Author(s):  
К.Н. Волков ◽  
В.Н. Емельянов ◽  
А.В. Ефремов ◽  
А.И. Цветков
Keyword(s):  
Atmospheric Pressure ◽  
Acoustic Waves ◽  
Supersonic Jet ◽  
Cavity Resonator ◽  
Dynamic Structure ◽  
Gas Jet ◽  
Working Pressure ◽  
Gas Dynamic ◽  
Physical Pattern ◽  
Cylindrical Cavities

In high-pressure gas-jet emitters, the source of sound energy is kinetic energy of gas jet at supercritical pressure ratios between the working pressure and the atmospheric pressure. Under certain conditions, interaction of a supersonic jet with the resonator is accompanied by powerful self-excited oscillating process with the generation of acoustic waves into the environment and cavity resonator. A model of a self-excited oscillating process arising from the interaction of non-isobaric jet with semi-closed cylindrical cavities, allowing to distinguish typical elements of gas-dynamic structure of the forming flow, is considered. The physical pattern of the flow in the cavity of gas-jet emitter is discussed, and a study of the dependence of the characteristics of the self-excited oscillating process on the gas-dynamic and geometric parameters is performed.

On the impingement of a supersonic jet on a flat plate

1969 ◽  
Vol 20 (1) ◽  
pp. 15-18 ◽  
Author(s):  
Chong-Wei Chu ◽  
S. A. Powers ◽  
H. Ziegler
Keyword(s):  
Flat Plate ◽  
Supersonic Jet

Numerical Analysis of Droplet Motion over a Flat Plate Due to Surface Acoustic Waves

2020 ◽  
Vol 32 (4) ◽  
pp. 647-660 ◽  
Author(s):  
S. M. Sheikholeslam Noori ◽  
M. Taeibi Rahni ◽  
S. A. Shams Taleghani
Keyword(s):  
Numerical Analysis ◽  
Flat Plate ◽  
Acoustic Waves ◽  
Surface Acoustic Waves ◽  
Droplet Motion

Investigation of tone generation in ideally expanded supersonic planar impinging jets using large-eddy simulation

2016 ◽  
Vol 808 ◽  
pp. 90-115 ◽  
Author(s):  
Romain Gojon ◽  
Christophe Bogey ◽  
Olivier Marsden
Keyword(s):  
Flat Plate ◽  
Acoustic Waves ◽  
Impinging Jets ◽  
Wave Analysis ◽  
Mean Velocity ◽  
Planar Jet ◽  
Feedback Model ◽  
Low Dissipation ◽  
Large Eddy ◽  
Oscillation Modes

The generation of tones in a supersonic planar jet impinging on a flat plate normally has been investigated by performing compressible large-eddy simulations using low-dissipation and low-dispersion finite differences. At the exit of a straight nozzle of height $h$, the jet is ideally expanded, and has a Mach number of 1.28 and a Reynolds number of $5\times 10^{4}$. Four distances between the nozzle and the plate between $3.94h$ and $9.1h$ have been considered. Flow snapshots and mean velocity fields are first presented. The variations of turbulence intensities and of the convection velocity in the jet shear layers are then examined. The properties of the jet near fields are subsequently described, in particular by applying Fourier decomposition to the pressure fields. Several coexisting tones appear to be generated by aeroacoustic feedback loops establishing between the nozzle lip and the flat plate, which also lead to the presence of hydrodynamic–acoustic standing waves. The tone frequencies are consistent with those given by the aeroacoustic feedback model and with measurements for high-aspect-ratio rectangular jets. The jet oscillation modes at these frequencies are characterized, and found to agree with experimental data. Their symmetric or antisymmetric natures are shown to be well predicted by a wave analysis carried out using a vortex sheet model of the jet, providing the allowable frequency ranges for the upstream-propagating acoustic waves. Thus, it is possible, for an ideally expanded impinging planar jet to predict both the frequencies of the tones and the symmetric or antisymmetric nature of the corresponding oscillation modes by combining the aeroacoustic feedback model and the wave analysis.

scholarly journals Conditional Sampling Analysis of Acoustic Phenomena from a Supersonic Jet Impinging on an Inclined Flat Plate

2016 ◽  
Vol 59 (5) ◽  
pp. 287-294 ◽  
Author(s):  
Masahito AKAMINE ◽  
Koji OKAMOTO ◽  
Susumu TERAMOTO ◽  
Takeo OKUNUKI ◽  
Seiji TSUTSUMI
Keyword(s):  
Flat Plate ◽  
Supersonic Jet ◽  
Conditional Sampling

Disintegration of a supersonic jet impinging normally on a flat plate

1971 ◽  
Vol 8 (4) ◽  
pp. 410-411 ◽  
Author(s):  
T. NAKATOGAWA ◽  
M. HIRATA ◽  
Y. KUKITA
Keyword(s):  
Flat Plate ◽  
Supersonic Jet
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