Gasdynamic and Acoustic Characteristics of a Subsonic Jet-Edge Rod Generator of Acoustic Radiation

2020 ◽  
Vol 93 (5) ◽  
pp. 1179-1190
Author(s):  
K. N. Volkov ◽  
V. N. Emel’yanov ◽  
A. V. Efremov ◽  
A. I. Tsvetkov
Keyword(s):  
Acoustic Radiation ◽  
Acoustic Characteristics ◽  
Subsonic Jet

6—The Instability of Two Vortex Sheets Enclosing a Subsonic Jet due to Acoustic Radiation

1974 ◽  
Vol 72 (1) ◽  
pp. 79-91 ◽  
Author(s):  
N. Hardisty
Keyword(s):  
Acoustic Radiation ◽  
Vortex Sheets ◽  
Instability Waves ◽  
Subsonic Jet

SummaryThe propagation of sound in a subsonic jet separated by two vortex sheets from two semi-infinite still media is considered and it is found that instability waves arise at particular points on the vortex sheets and that their effect is confined to certain regions.

Acoustic Characteristics of a Gas Turbine Exhaust Model

1974 ◽  
Vol 96 (3) ◽  
pp. 181-184 ◽  
Author(s):  
J. R. Cummins
Keyword(s):  
Gas Turbine ◽  
Acoustic Radiation ◽  
Flow Path ◽  
Scale Model ◽  
Temperature Ratio ◽  
Acoustic Characteristics ◽  
Gas Turbine Exhaust ◽  
Acoustical Data ◽  
Turbine Exhaust

To investigate the sources of acoustic radiation from a gas turbine exhaust, a one-seventh scale model has been constructed. The model geometrically scales the flow path downstream of the rotating parts including support struts and turning vanes. A discussion and comparison of different kinds of aerodynamic and acoustic scaling techniques are given. The effect of the temperature ratio between model and prototype is found to be an important parameter in comparing acoustical data.

Shear-layer acoustic radiation in an excited subsonic jet: experimental study

2005 ◽  
Vol 333 (10) ◽  
pp. 746-753 ◽  
Author(s):  
Vincent Fleury ◽  
Christophe Bailly ◽  
Daniel Juvé
Keyword(s):  
Experimental Study ◽  
Shear Layer ◽  
Acoustic Radiation ◽  
Subsonic Jet

USE OF GROOVED SURFACES TO IMPROVE HYDRODYNAMIC, CAVITATION AND ACOUSTIC CHARACTERISTICS OF WINGS AND ELEMENTS OF VANE PROPULSION SYSTEMS (REVIEW)

2021 ◽  
Vol 2 ◽  
pp. 3-17
Author(s):  
A.L. SUKHORUKOV
Keyword(s):  
Computational Models ◽  
Acoustic Radiation ◽  
Hydrodynamic Cavitation ◽  
Propulsion Systems ◽  
Acoustic Characteristics ◽  
Flow Parameters ◽  
Turbulent Transition ◽  
Grooved Surface ◽  
Propeller Blades ◽  
Laminar Turbulent Transition

The paper reviews the use of grooved surfaces and sawtooth (chevron) edges to control the flow parameters of the wings, propeller blades and elements of vane propulsion systems operating in both gaseous and liquid media. Particular attention is paid to the physical mechanisms of improving the hydrodynamic, cavitation and acoustic characteristics under the influence of a grooved surface. These mechanisms are associated with a change in the flow structure in the region of the laminar-turbulent transition, the peculiarities of the occurrence of cavitation and acoustic radiation in the region of the outgoing edges. The results of the verification of computational models describing the behavior of the flow taking into account the laminar-turbulent transition, the use of which is necessary for studying flows near a grooved surface, are presented.

scholarly journals THE STUDY OF ACOUSTIC CHARACTERISTICS OF THE PERFORATED AND HOMOGENOUS PLATES WITH SIMILAR GEOMETRICAL DIMENSIONS

Akustika ◽  
2019 ◽  
Vol 32 ◽  
pp. 79-82
Author(s):  
Valery Kirpichnikov ◽  
Lyudmila Drozdova ◽  
Alexei Koscheev ◽  
Ernst Myshinsky
Keyword(s):  
Resonant Frequency ◽  
Acoustic Radiation ◽  
Perforated Plate ◽  
Acoustic Characteristics ◽  
Resonant Frequencies ◽  
Perforated Plates ◽  
Resonance Frequencies ◽  
Flexural Vibrations ◽  
Geometrical Dimensions

The resonance frequencies of the flexural vibrations, input vibration excitability and acoustic radiation of the homogeneous and perforated plates were investigated. It is established that the average reduction range of the lower resonant frequency of flexural vibrations of the tested plates with the holes virtually coincides with the predictive estimate. The levels of the input vibration excitability of the perforated plate at the lower resonant frequencies exceeded the levels at the corresponding frequencies of the homogeneous plates greater than the calculated value. The levels of resonance acoustic radiation of the perforated plate were significantly less than of the homogeneous one.

Research on Vibro-Acoustic Characteristics of Underwater Finite Plate-Shell Structure under Multiple Excitations

2013 ◽  
Vol 834-836 ◽  
pp. 1351-1359
Author(s):  
Yong Yong Zhu
Keyword(s):  
Shell Structure ◽  
Acoustic Radiation ◽  
Radiation Power ◽  
Acoustic Vibration ◽  
Finite Cylinder ◽  
Acoustic Characteristics ◽  
Theory Of Plates ◽  
Plates And Shells ◽  
Vibration Coupling ◽  
Finite Cylindrical Shell

An analysis based on the first kind of Lagranges equations was presented for investigating the vibration and acoustic radiation of underwater finite cylindrical shell with interior plate under multiple excitations. The strain energy and kinetic energy of cylinder and plate were gained by the theory of plates and shells, and the potential energy of excitation and fluid loading was found based on acoustic-vibration coupling, and the connection conditions of plate and cylinder were expressed by Lagrange multipliers, then the vibro-acoustic equations of finite cylinder with interior plate under shafting excitation were established. The influences of excitations and plates position to the vibro-acoustic characteristics were studied by the equations. The results show that the frequency components of plate-shell structure are more complex. For the double excitations on plate, the distance between excitations is larger, the average velocity and sound radiation power are lower, while the radiation efficiency is larger. The modeling and analytical methods adopted in this paper are also available for more complex composite structure.

Acoustic Characteristics of a High-Subsonic Jet

AIAA Journal ◽  
1971 ◽  
Vol 9 (6) ◽  
pp. 1058-1066 ◽  
Author(s):  
L. MAESTRELLO ◽  
E. McDAID
Keyword(s):  
Acoustic Characteristics ◽  
Subsonic Jet

Global response to forcing in a subsonic jet: instability wavepackets and acoustic radiation

2013 ◽  
Author(s):  
Xavier Garnaud ◽  
Richard D. Sandberg ◽  
Lutz Lesshafft
Keyword(s):  
Acoustic Radiation ◽  
Global Response ◽  
Jet Instability ◽  
Subsonic Jet

Studies of Acoustic Characteristics and Their Comparison With Vibration Ones

1995 ◽  
Author(s):  
Alexander E. Ekimov
Keyword(s):  
Transfer Coefficient ◽  
Distributed System ◽  
Acoustic Radiation ◽  
Physical Models ◽  
System Model ◽  
Acoustic Fields ◽  
Transfer Coefficients ◽  
Acoustic Characteristics ◽  
Reciprocity Method ◽  
Force Characteristics

Abstract The present paper gives the methods, schemes and results of experiments based on direct and reciprocal methods of measurements. The use of the reciprocity method made it possible to solve the problem of determining the acoustic characteristics of the distributed system model where vibroactive sources are represented in the form of passive models. It has been shown that the normalized transfer coefficient characterizing a link between force and acoustic fields has the same value both for the model and in nature (in case of their full similarity) that can be used: - to improve the methods of designing and technological manufacturing of models based on the comparison of normalized transfer coefficients obtained for full-scale and physical models; - to forecast the acoustic radiation of some vibroactive mechanisms using the assigned force characteristics and normalized transfer coefficients obtained for a model with the modelling scale taken into account.

АКУСТИЧНА ПОМІТНІСТЬ БЕЗПІЛОТНИХ ЛІТАЛЬНИХ АПАРАТІВ З СИЛОВОЮ УСТАНОВКОЮ, ЩО МІСТИТЬ ЕЛЕКТРОДВИГУН І ПОВІТРЯНИЙ ГВИНТ

2020 ◽  
pp. 81-94
Author(s):  
В. В. Руденко ◽  
В. П. Чернолихова
Keyword(s):  
Power Plant ◽  
Electric Motor ◽  
Acoustic Radiation ◽  
Spectral Characteristics ◽  
Experimental Studies ◽  
Noise Spectrum ◽  
Acoustic Characteristics ◽  
Acoustic Signature ◽  
Constant Pitch ◽  
Static Conditions

The presence in operation of many prototypes of UAVs with propeller propellers, the use of such devices at relatively low altitudes and flight speeds makes the problem of reducing the noise generated during UAV flights urgent both from the point of view of acoustic visibility and ecology.The main source of the UAV's acoustic signature is its power plant, which includes the engine and propeller.The tasks of this work, the solution of which requires the implementation of experimental studies, include the determination of the power, spatial and spectral characteristics of the acoustic fields of propeller driven power plants of UAVs with an electric drive. The propeller is one of the main sources of acoustic radiation produced by the power plant. The influence on the acoustic characteristics of the power plant was investigated: changes in the diameter of the propellers with a constant pitch, changes in the number of blades and the number of revolutions (peripheral speeds of the propeller). The possibility of reducing the noise produced by the propeller by changing the nature of the noise spectrum was considered. The rotor rotation noise, especially of its five first harmonics, is one of the most noticeable parts in the noise spectrum of a propeller engine installation. Therefore, a hypothesis was considered and put into practice to reduce the acoustic signature of UAVs by reducing the noise of these components due to their shift to the region of higher frequencies, at which sound vibrations in the air decay faster. A comparison technique is proposed. The measurements were carried out under static conditions, in the KhAI anechoic chamber. Note that the propellers involved in the experiments operated at Reynolds numbers (Re0.75 <1*105), which can significantly affect its aerodynamic and acoustic characteristics. An empirical formula was obtained for the 11 × 6" «Aero-naut» propeller, which makes it possible to estimate the noise produced by this propeller when designing for a given flight mode in a given direction. The possibility was considered in the future to have a database of frequently used propellers. The contribution of harmonic noise components was considered propeller in the direction of its radiation. The contribution of the brushless electric motor to the intensity of acoustic radiation of the UAV power plant is determined. It is noted that the main contribution to the noise of a power plant with a brushless electric motor is made by the propeller. At the same time, the noise of a brushless electric motor can significantly increase in the range of 2 ... 3 kHz with wear of rolling bearings.

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