Date

2014

Author

Batmaz, Ömer

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Today, towed arrays are widely utilized in both civilian and military applications such as oil/gas explorations or submarine/torpedo detections under the water. Hydrophones are linearly arranged in the acoustic section of a towed array. These hydrophones convert the reverberated acoustical signals from targets into electrical signals and send them to the data acquisition center on the tow vessel. Any kind of noise on hydrophones negatively affects the performance of the array during operation. Vibrations coming from the tow cable and drogue rope are important noise mechanisms; especially at low working frequencies and tow speeds. In order to suppress these vibrations from the hydrophone section and hence increase the signal-to-noise ratio of the array, vibration isolation modules (VIMs) are attached to forward and aft ends of the hydrophone section. During the design phase of the VIM, it is highly desirable to be able to predict the dynamic behavior of the module. Consequently, this study was undertaken in order to determine the modal characteristics of the VIM. Firstly, Myklestad’s Method for bending was used to build up mathematical model of the VIM. Since the VIM structure is not slender and there is always considerable drag force on the VIM during operation, shear effects and variable tension force were implemented to the method. A vertically hung VIM was tested to provide both free-free boundary condition and variable tension. The study was concluded with a thorough comparison of the theoretical and experimental results in order to evaluate the effectiveness of the modified method.

Subject Keywords

Underwater acoustics., Hydrophone., Sonar., Towed array., Vibration isolation.

URI

http://etd.lib.metu.edu.tr/upload/12617069/index.pdf
https://hdl.handle.net/11511/23448

Collections

Graduate School of Natural and Applied Sciences, Thesis