Exploration of temperature effects on the far-field acoustic radiation from a supersonic jet

2014 ◽  
Author(s):  
Haukur E. Hafsteinsson ◽  
Lars-Erik Eriksson ◽  
Niklas Andersson ◽  
Pablo A. Mora Sanchez ◽  
Ephraim J. Gutmark ◽  
...  
Keyword(s):  
Temperature Effects ◽  
Acoustic Radiation ◽  
Supersonic Jet ◽  
Far Field

Global modes and transient response of a cold supersonic jet

2011 ◽  
Vol 669 ◽  
pp. 225-241 ◽  
Author(s):  
JOSEPH W. NICHOLS ◽  
SANJIVA K. LELE
Keyword(s):  
Acoustic Radiation ◽  
Near Field ◽  
Supersonic Jet ◽  
Mode Analysis ◽  
Wave Radiation ◽  
Far Field ◽  
Transient Growth ◽  
Global Mode ◽  
Laminar Jet ◽  
Global Modes

Global-mode analysis is applied to a cold, M = 2.5 laminar jet. Global modes of the non-parallel jet capture directly both near-field dynamics and far-field acoustics which, in this case, are coupled by Mach wave radiation. In addition to type (a) modes corresponding to Kelvin–Helmholtz instability, it is found that the jet also supports upstream-propagating type (b) modes which could not be resolved by previous analyses of the parabolized stability equations. The locally neutrally propagating part of a type (a) mode consists of the growth and decay of an aerodynamic wavepacket attached to the jet, coupled with a beam of acoustic radiation at a low angle to the jet downstream axis. Type (b) modes are shown to be related to the subsonic family of modes predicted by Tam & Hu (1989). Finally, significant transient growth is recovered by superposing damped, but non-normal, global modes, leading to a novel interpretation of jet noise production. The mechanism of optimal transient growth is identified with a propagating aerodynamic wavepacket which emits an acoustic wavepacket to the far field at an axial location consistent with the peaks of the locally neutrally propagating parts of type (a) modes.

scholarly journals Study on Acoustic Radiation Calculation and Far Field Criterion of Oil pan

2021 ◽  
Vol 1043 (4) ◽  
pp. 042062
Author(s):  
Yue-zhen Huang ◽  
Bo Zhang ◽  
Ke-lun Zhao ◽  
Xue-bao Xia
Keyword(s):  
Acoustic Radiation ◽  
Far Field ◽  
Field Criterion

Relationships Between Acoustic Radiation Modes, Complex Acoustic Power, and Radiation Efficiency

1997 ◽  
Author(s):  
Pei-Tai Chen
Keyword(s):  
Acoustic Radiation ◽  
Acoustic Power ◽  
Radiation Efficiency ◽  
Acoustic Energy ◽  
Normal Velocity ◽  
Far Field ◽  
Surface Complex ◽  
Surface Integral ◽  
Complex Power ◽  
Mass Spring

Abstract The paper explores the physical meaning underlying the surface complex acoustic power of a vibrating body, and its relationship to radiation efficiency under mono-frequency oscillations. The vibrating can be the entire wetted surface, or only a part of the surface with the remaining surface being held rigid. The surface complex acoustic power can be computed by the surface integral of pressure multiplying the complex conjugate of normal velocity. Based on the Gaussian Divergence theorem, it is shown that the real part of the complex power is the power radiated into a far field, while that the imaginary part pertains to the volume integral of the difference between the acoustic kinetic energy density with the potential energy density over the volume between the vibrating surface and the far field. The dynamical behavior of the acoustic field can be viewed as an infinite degree of freedom mass/spring/dashpot system, where the mass and spring are the inertia effects and acoustic compression effects of the acoustic particles and the dashpot is due to the plane wave relationship of the pressure waves at the far field that the acoustic energy propagates away from the acoustic field. By the model of the mass /spring/dashpot system, the phase angle of the complex acoustic power is identified as an indication of the ability of the vibrating surface to radiate acoustic power. The phase angle of the complex power depends on the distribution of the surface normal velocity. In order to study the normal velocity profile in relation to the ability to radiate acoustic energy, the previously established radiation mode (Chen and Ginsberg, 1995) is introduced and extended to situations in which a part of the surface is held rigid. An orthogonal condition for the velocity radiation modes is also established such that arbitrary velocity profiles can be decomposed into radiation modes. The acoustic modal radiation efficiency, defined as the radiated modal acoustic power divided by the surface integral of mean square normal velocity, is investigated in terms of the acoustic eigenvalue of that mode. Several different geometries of vibrating bodies are used to demonstrate the correlation of radiation efficiencies to eigenvalues of radiation modes, which include a rectangular baffled vibrating membrane, a box with only one of the six surfaces vibrating, a slender spheroidal body, and a spherical body. This correlation of acoustic radiation characteristics for different geometries is also demonstrated for a spheroidal body vibrating at some areas with other areas being held rigid.

Flight Effects on the Far-Field Noise of a Heated Supersonic Jet

AIAA Journal ◽  
10.2514/2.203 ◽  
1997 ◽  
Vol 35 (6) ◽  
pp. 952-957 ◽  
Author(s):  
A. Krothapalli ◽  
P. T. Soderman ◽  
C. S. Allen ◽  
J. A. Hayes ◽  
S. M. Jaeger
Keyword(s):  
Supersonic Jet ◽  
Far Field ◽  
Field Noise

Near-Field and Far-Field Spectral Analysis of Supersonic Jet with and without Fluidic Injection

2014 ◽  
Author(s):  
Haukur E. Hafsteinsson ◽  
Lars-Erik Eriksson ◽  
Niklas Andersson ◽  
Daniel R. Cuppoletti ◽  
Ephraim J. Gutmark ◽  
...  
Keyword(s):  
Spectral Analysis ◽  
Near Field ◽  
Supersonic Jet ◽  
Far Field

Prediction of Far-Field Sound Pressure of a Semisubmerged Cylindrical Shell With Low-Frequency Excitation

2017 ◽  
Vol 139 (4) ◽  
Author(s):  
T. Y. Li ◽  
P. Wang ◽  
X. Zhu ◽  
J. Yang ◽  
W. B. Ye
Keyword(s):  
Cylindrical Shell ◽  
Free Surface ◽  
Sound Pressure ◽  
Acoustic Radiation ◽  
Phase Method ◽  
Far Field ◽  
Radiation Model ◽  
New Approaches ◽  
Modal Coupling ◽  
Field Sound

A sound–structure interaction model is established to study the vibroacoustic characteristics of a semisubmerged cylindrical shell using the wave propagation approach (WPA). The fluid free surface effect is taken into account by satisfying the sound pressure release condition. Then, the far-field sound pressure is predicted with shell's vibration response using the stationary phase method. Modal coupling effect arises due to the presence of the fluid free surface. New approaches are proposed to handle this problem, i.e., diagonal coupling acoustic radiation model (DCARM) and column coupling acoustic radiation model (CCARM). New approaches are proved to be able to deal with the modal coupling problem efficiently with a good accuracy at a significantly reduced computational cost. Numerical results also indicate that the sound radiation characteristics of a semisubmerged cylindrical shell are quite different from those from the shell fully submerged in fluid. But the far-field sound pressure of a semisubmerged shell fluctuates around that from the shell ideally submerged in fluid. These new approaches can also be used to study the vibroacoustic problems of cylindrical shells partially coupled with fluid.

Sign in / Sign up

Export Citation Format

Share Document