Use of acoustic basis functions for active control of sound power radiated from a cylindrical shell

1998 ◽  
Vol 103 (4) ◽  
pp. 1897-1903 ◽  
Author(s):  
Koorosh Naghshineh ◽  
Weicheng Chen ◽  
Gary H. Koopmann
Keyword(s):  
Cylindrical Shell ◽  
Active Control ◽  
Basis Functions ◽  
Sound Power

Active control of sound power using acoustic basis functions

1993 ◽  
Vol 94 (3) ◽  
pp. 1816-1816
Author(s):  
Koorosh Naghshineh ◽  
Gary H. Koopmann
Keyword(s):  
Active Control ◽  
Basis Functions ◽  
Sound Power

ACTIVE CONTROL OF A MACHINE SUSPENSION SYSTEM SUPPORTED ON A CYLINDRICAL SHELL

2013 ◽  
Vol 21 (03) ◽  
pp. 1350012
Author(s):  
X. LIU ◽  
G. JIN ◽  
Y. WANG ◽  
Y. SHI ◽  
X. FENG
Keyword(s):  
Cylindrical Shell ◽  
Numerical Simulations ◽  
Active Control ◽  
Numerical Study ◽  
Control Strategies ◽  
Acoustic Power ◽  
Suspension System ◽  
Sound Power ◽  
Control Force ◽  
Power Minimization

A numerical study on the active control of a machine suspension system supported on a cylindrical shell aiming to reduce the sound radiation is presented in this paper. In this system, a rigid-body machine is supported on a simply-supported elastic cylindrical shell through four active isolators. A theoretical model is employed and four types of active control strategies including kinetic energy minimization strategy, power flow minimization strategy, squared acceleration minimization strategy and acoustic power minimization strategy are considered, with corresponding active control force obtained by linear quadratic optimal method. Numerical simulations are conducted and detailed results were presented. Active control performance under these four control strategies is compared and analyzed in terms of radiated sound power, and the effect of the number of active actuators is discussed by numerical analysis. The results show that acoustic power minimization strategy has the best performance to reduce the sound power radiated from supporting shell in general. Through numerical simulations, some comprehensive design principles of active control system are discussed at the end.

Active control of radiated sound power of a smart cylindrical shell based on radiation modes

2016 ◽  
Vol 114 ◽  
pp. 218-229 ◽  
Author(s):  
Ali Loghmani ◽  
Mohammad Danesh ◽  
Moon K. Kwak ◽  
Mehdi Keshmiri
Keyword(s):  
Cylindrical Shell ◽  
Active Control ◽  
Sound Power ◽  
Radiated Sound ◽  
Radiated Sound Power

scholarly journals Investigation of Low-Frequency Sound Radiation Characteristics and Active Control Mechanism of a Finite Cylindrical Shell

2021 ◽  
Vol 2021 ◽  
pp. 1-16
Author(s):  
Shaohu Ding ◽  
Chunyang Mu ◽  
Yang Gao ◽  
Hong Liu ◽  
Maoqiang Li
Keyword(s):  
Cylindrical Shell ◽  
Active Control ◽  
Physical Mechanism ◽  
Sound Power ◽  
Radiation Characteristics ◽  
Low Frequencies ◽  
Acoustic Control ◽  
Radiated Sound ◽  
Finite Cylindrical Shell ◽  
Structural Acoustic Control

In this paper, the radiation characteristics and active structural acoustic control of a submerged cylindrical shell at low frequencies are investigated. First, the coupled vibro-acoustic equations for a submerged finite cylindrical shell are solved by a modal decomposition method, and the radiation impedance is obtained by the fast Fourier transform. The modal shapes of the first ten acoustic radiation modes and the structure-dependent radiation modes are presented. The relationships between the vibration modes and the radiation modes as well as the contributions of the radiation modes to the radiated sound power are given at low frequencies. Finally, active structural acoustic control of a submerged finite cylindrical shell is investigated by considering the fluid-structure coupled interactions. The physical mechanism of the active control is discussed based on the relationship between the vibration and radiation modes. The results showed that, at low frequencies, only the first several radiation modes contributed to the sound power radiated from a submerged finite cylindrical shell excited by a radial point force. By determining the radiation modes that dominate the contribution to the radiated sound, the physical mechanism of the active control is explained, providing a potential tool to allow active control of the vibro-acoustic responses of submerged structures more effectively.

Active control of compressor noise in the machinery room of refrigerators

2019 ◽  
Vol 67 (5) ◽  
pp. 350-362
Author(s):  
J. M. Ku ◽  
W. B. Jeong ◽  
C. Hong
Keyword(s):  
Control System ◽  
Active Control ◽  
Weighting Function ◽  
Reference Signal ◽  
Active Noise Control ◽  
Dominant Frequency ◽  
Time Signal ◽  
Frequency Noise ◽  
Sound Power ◽  
Fxlms Algorithm

The low-frequency noise generated by the vibration of the compressor in the machinery room of refrigerators is considered as annoying sound. Active noise control is used to reduce this noise without any change in the design of the compressor in the machinery room. In configuring the control system, various signals are measured and analyzed to select the reference signal that best represents the compressor noise. As the space inside the machinery room is small, the size of a speaker is limited, and the magnitude of the controller transfer function is designed to be small at low frequencies, the controller uses FIR filter structure converged by the FxLMS algorithm using the pre-measured time signal. To manage the convergence speed for each frequency, the frequency-weighting function is applied to FxLMS algorithm. A series of measurements are performed to design the controller and to evaluate the control performance. After the control, the sound power transmitted by the refrigerator is reduced by 9 dB at the first dominant frequency (408 Hz in this case) and 3 dB at the second dominant frequency (459 Hz here), and the overall sound power decreases by 2.6 dB. Through this study, an active control system for the noise generated by refrigerator compressors is established.

VIBRO-ACOUSTIC RESPONSE OF A CIRCULAR ISOTROPIC CYLINDRICAL SHELL UNDER A THERMAL ENVIRONMENT

2011 ◽  
Vol 03 (03) ◽  
pp. 525-541 ◽  
Author(s):  
P. JEYARAJ ◽  
C. PADMANABHAN ◽  
N. GANESAN
Keyword(s):  
Cylindrical Shell ◽  
Thermal Environment ◽  
Power Level ◽  
Mode Shapes ◽  
Sound Power ◽  
Sudden Increase ◽  
Acoustic Response ◽  
Response Characteristics ◽  
Sound Power Level ◽  
Isotropic Cylindrical Shell

This paper presents numerical simulation studies on the vibration and acoustic response-characteristics of an isotropic cylindrical shell under a thermal environment using commercial softwares ANSYS and SYSNOISE. First, the critical buckling temperature is obtained, followed by modal and harmonic response analyses considering pre-stress due to the thermal field in the cylindrical shell, with the critical buckling temperature as a parameter. The vibration response predicted is then used to compute the sound radiation. It is found that there is a significant change in the vibration mode shapes and ring frequency towards the lowest natural frequency with an increase in temperature. There is a sudden increase in overall sound power level near the critical buckling temperature and significant changes in mode shapes with temperature does not affect the overall sound power level.

Passive and Active Control of the Radiated Sound Power from a Submarine Excited by Propeller Forces

2013 ◽  
Vol 57 (1) ◽  
pp. 59-71 ◽  
Author(s):  
Sascha Merz ◽  
Nicole Kessissoglou ◽  
Roger Kinns ◽  
Steffen Marburg
Keyword(s):  
Active Control ◽  
Sound Power ◽  
Radiated Sound ◽  
Radiated Sound Power

Influence of Boundary Conditions on the Active Control of Vibration and Sound Radiation for a Circular Cylindrical Shell

2011 ◽  
Vol 66-68 ◽  
pp. 1270-1277
Author(s):  
Lu Dai ◽  
Tie Jun Yang ◽  
Yao Sun ◽  
Ji Xin Liu
Keyword(s):  
Cylindrical Shell ◽  
Boundary Conditions ◽  
Active Control ◽  
Structural Engineering ◽  
Acoustic Radiation ◽  
Circular Cylindrical Shell ◽  
Acoustic Power ◽  
Fourier Series Method ◽  
Vibration And Sound Radiation ◽  
Elastically Restrained

Vibration and acoustic radiation of circular cylindrical shells are hot topics in the structural engineering field. However for a long period, this sort of problems is only limit to classical homogeneous boundary conditions. In this paper, the vibration of a circular cylindrical shell with elastic boundary supports is studied using modified Fourier series method, and the far-field pressure for a baffled shell is calculated by Helmholtz integral equation. Active control of vibration and acoustic radiation are carried out by minimizing structural kinetic energy and radiated acoustic power respectively. The influence of boundary conditions on the active control is investigated throughout several numerical examples. It is shown that the active control of vibration and acoustic for an elastically restrained shell can exhibit unexpected and complicated behaviors.

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