Character of Mach Wave Radiation and Convection Velocity Estimation in Supersonic Shear Layers

2002 ◽  
Author(s):  
Tobias Rossmann ◽  
Godfrey Mungal ◽  
Ronald Hanson
Keyword(s):  
Shear Layers ◽  
Velocity Estimation ◽  
Convection Velocity ◽  
Wave Radiation ◽  
Mach Wave ◽  
Supersonic Shear Layers

Aerodynamic noise emission from turbulent shear layers

1973 ◽  
Vol 59 (3) ◽  
pp. 451-479 ◽  
Author(s):  
S. P. Pao
Keyword(s):  
Wave Equation ◽  
Fourier Transformation ◽  
Shear Layers ◽  
Aerodynamic Noise ◽  
Wave Radiation ◽  
Turbulent Shear ◽  
Noise Emission ◽  
Round Jets ◽  
Spatial Dimensions ◽  
Supersonic Shear Layers

The Phillips (1960) convected wave equation is employed in this paper to study aerodynamic noise emission processes in subsonic and supersonic shear layers. The wave equation in three spatial dimensions is first reduced to an ordinary differential equation by Fourier transformation, then solved via the WKBJ method. Three typical solutions are required for discussions in this paper. The current results are different from the classical conclusions. The effects of refraction, convection, Mach-number dependence and temperature dependence of turbulent noise emission are analysed in the light of solutions to the Phillips equation. Owing to the inherent restrictions of the WKBJ transformation, the results of the present paper should be applied to wave radiation from shear layers whose thickness is no less than approximately one quarter of a wavelength. Such a condition is satisfied for turbulent round jets with an exit velocity greater than 0·6 times the ambient speed of sound.

scholarly journals Mach Wave Radiation from a Jet at Mach 1.92

2001 ◽  
Vol 13 (9) ◽  
pp. S3-S3 ◽  
Author(s):  
R. Darke ◽  
J. B. Freund
Keyword(s):  
Wave Radiation ◽  
Mach Wave

A study of Mach wave radiation using active control

2011 ◽  
Vol 681 ◽  
pp. 261-292 ◽  
Author(s):  
M. KEARNEY-FISCHER ◽  
J.-H. KIM ◽  
M. SAMIMY
Keyword(s):  
Large Scale ◽  
Near Field ◽  
Pressure Fluctuations ◽  
Hydrodynamic Pressure ◽  
Detailed Examination ◽  
Operating Conditions ◽  
Wave Radiation ◽  
Stagnation Temperature ◽  
Azimuthal Mode ◽  
Mach Wave

Mach wave radiation is one of the better understood sources of jet noise. However, the exact conditions of its onset are difficult to determine and the literature to date typically explores Mach wave radiation well above its onset conditions. In order to determine the conditions for the onset of Mach wave radiation and to explore its behaviour during onset and beyond, three ideally expanded jets with Mach numbers Mj = 0.9, 1.3 and 1.65 and stagnation temperature ratios ranging over To/T∞ = 1.0–2.5 (acoustic Mach number 0.83–2.10) were used. Data are collected using a far-field microphone array, schlieren imaging and streamwise two-component particle image velocimetry. Using arc filament plasma actuators to force the jet provides an unprecedented tool for detailed examination of Mach wave radiation. The response of the jet to various forcing parameters (combinations of one azimuthal mode m = 0, 1 and 3 and one Strouhal number StDF = 0.09–3.0) is explored. Phase-averaged schlieren images clearly show the onset and evolution of Mach wave radiation in response to both changes in the jet operating conditions and forcing parameters. It is observed that Mach wave radiation is initiated as a coalescing of the near-field hydrodynamic pressure fluctuations in the immediate vicinity of the large-scale structures. As the jet exit velocity increases, the hydrodynamic pressure fluctuations coalesce, first into a curved wavefront, then flatten into the conical wavefronts commonly associated with Mach wave radiation. The results show that the largest and most coherent structures (e.g. forcing with m = 0 and StDF ~ 0.3) produce the strongest Mach wave radiation. Conversely, Mach wave radiation is weakest when the structures are the least coherent (e.g. forcing with m = 3 and StDF > 1.5).

scholarly journals Conditional sampling analysis of high-speed schlieren movies of Mach wave radiation in a supersonic jet

2019 ◽  
Vol 145 (1) ◽  
pp. EL122-EL128 ◽  
Author(s):  
Masahito Akamine ◽  
Koji Okamoto ◽  
Susumu Teramoto ◽  
Seiji Tsutsumi
Keyword(s):  
High Speed ◽  
Supersonic Jet ◽  
Wave Radiation ◽  
Conditional Sampling ◽  
Mach Wave

Mixing enhancement in supersonic shear layers

1987 ◽  
Author(s):  
R. GUIRGUIS ◽  
F. GRINSTEIN ◽  
T. YOUNG ◽  
E. ORAN ◽  
K. KAILASANATH
Keyword(s):  
Shear Layers ◽  
Mixing Enhancement ◽  
Supersonic Shear Layers
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