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

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.

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A compact active structural acoustic control method for minimizing radiated sound power

INTER-NOISE and NOISE-CON Congress and Conference Proceedings ◽

10.3397/in-2021-2393 ◽

2021 ◽

Vol 263 (3) ◽

pp. 3396-3406

Author(s):

Scott Sommerfeldt

Keyword(s):

Control Method ◽

Acoustic Radiation ◽

Structural Vibration ◽

Sound Power ◽

Flat Plates ◽

Spatial Gradients ◽

Acoustic Control ◽

Radiated Sound ◽

Radiated Sound Power ◽

Structural Acoustic Control

Active structural acoustic control is an active control method that controls a vibrating structure in a manner that reduces the sound power radiated from the structure. Such methods focus on attenuating some metric that results in attenuated sound power, while not necessarily minimizing the structural vibration. The work reported here outlines the weighted sum of spatial gradients (WSSG) control metric as a method to attenuate structural radiation. The WSSG method utilizes a compact error sensor that is able to measure the acceleration and the acceleration gradients at the sensor location. These vibration signals are combined into the WSSG metric in a manner that is closely related to the radiated sound power, such that minimizing the WSSG also results in a minimization of the sound power. The connection between WSSG and acoustic radiation modes will be highlighted. Computational and experimental results for both flat plates and cylindrical shells will be presented, indicating that the WSSG method can achieve near optimal attenuation of the radiated sound power with a minimum number of sensors.

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

Applied Acoustics ◽

10.1016/j.apacoust.2016.07.027 ◽

2016 ◽

Vol 114 ◽

pp. 218-229 ◽

Cited By ~ 6

Author(s):

Ali Loghmani ◽

Mohammad Danesh ◽

Moon K. Kwak ◽

Mehdi Keshmiri

Keyword(s):

Cylindrical Shell ◽

Active Control ◽

Sound Power ◽

Radiated Sound ◽

Radiated Sound Power

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Faster Calculation of the Low-Frequency Radiated Sound Power of Underwater Slender Cylindrical Shells

Mathematical Problems in Engineering ◽

10.1155/2020/3939160 ◽

2020 ◽

Vol 2020 ◽

pp. 1-10

Author(s):

Rui Tang ◽

He Tian ◽

Dajing Shang

Keyword(s):

Cylindrical Shell ◽

Cylindrical Shells ◽

Low Frequency ◽

Sound Radiation ◽

Sound Power ◽

Radiation Characteristics ◽

Calculation Process ◽

Radiated Sound ◽

Stiffened Cylindrical Shells ◽

Radiated Sound Power

Based on the fact that beam-type modes play the main role in determining the sound radiation from an underwater thin slender (length-to-radius ratio L/a>20) elastic cylindrical shell, an equivalent-beam method is proposed for calculating the low-frequency radiated sound power of underwater thin slender unstiffened and stiffened cylindrical shells. The natural bending frequencies of the cylindrical shell are calculated by analytical and numerical methods and used to solve equivalent Young’s modulus of the equivalent beam. This approach simplifies the vibration problem of the three-dimensional cylindrical shell into that of a two-dimensional beam, which can be used to simplify the calculation process of radiated sound power. Added mass is used to approximate the fluid-structure coupling, further simplifying the calculation process. Calculation examples of underwater simply supported unstiffened and stiffened cylindrical shells verify the proposed method by comparison with analytical and numerical results. Finally, the effects of the size and spacing of the stiffeners on the sound radiation characteristics of underwater free-free stiffened cylindrical shells are discussed. The proposed method can be extended to the rapid calculation of the sound radiation characteristics of underwater slender complex cylindrical shells in the low-frequency range.

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Active structural acoustic control from a vibrating cylindrical shell structure by force input

2010 2nd International Conference on Computer Engineering and Technology ◽

10.1109/iccet.2010.5486238 ◽

2010 ◽

Author(s):

Guoyong Jin ◽

Xiaoling Liu

Keyword(s):

Cylindrical Shell ◽

Shell Structure ◽

Acoustic Control ◽

Structural Acoustic Control

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

Journal of Ship Research ◽

10.5957/josr.57.1.100049 ◽

2013 ◽

Vol 57 (1) ◽

pp. 59-71 ◽

Cited By ~ 25

Author(s):

Sascha Merz ◽

Nicole Kessissoglou ◽

Roger Kinns ◽

Steffen Marburg

Keyword(s):

Active Control ◽

Sound Power ◽

Radiated Sound ◽

Radiated Sound Power

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Reduction of the Sound Pressure Radiated by a Submarine by Isolation of the End Caps

Journal of Vibration and Acoustics ◽

10.1115/1.4003198 ◽

2011 ◽

Vol 133 (3) ◽

Cited By ~ 7

Author(s):

Mauro Caresta ◽

Nicole J. Kessissoglou

Keyword(s):

Sound Pressure ◽

Low Frequency ◽

Axial Direction ◽

Radial Component ◽

Axial Motion ◽

Low Frequencies ◽

End Caps ◽

Passive Isolation ◽

Radiated Sound ◽

Finite Cylindrical Shell

A passive isolation approach to reduce the sound pressure radiated by a submarine is presented. The submerged vessel is modeled as a stiffened cylindrical hull partitioned by bulkheads and with two end caps of conical shape. Fluctuating forces from the propeller are transmitted to the hull through the shaft and a rigid foundation, resulting in axisymmetric excitation of the hull. The hull surface motion is mainly in the axial direction with a small radial component due to the coupling between the two orthogonal shell displacements. The sound pressure resulting from the axial motion is radiated from the end caps of the submarine. This work investigates reduction of the far field sound pressure by passive isolation of the end caps from the main hull. Isolation of the axial motion of the end caps from the cylindrical hull results in significant reduction of the radiated sound at low frequencies. The fluid loading approximation for a finite cylindrical shell in the low frequency range is also discussed.

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Measurement distance of underwater elastic cylindrical shell for radiated sound power

2016 IEEE/OES China Ocean Acoustics (COA) ◽

10.1109/coa.2016.7535653 ◽

2016 ◽

Author(s):

Yan Xiao ◽

Dejiang Shang ◽

Yuan Hu

Keyword(s):

Cylindrical Shell ◽

Elastic Cylindrical Shell ◽

Sound Power ◽

Radiated Sound ◽

Radiated Sound Power

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

Journal of Computational Acoustics ◽

10.1142/s0218396x13500124 ◽

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.

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