A general theory of the slotted cylinder projector (SCP) transducer: a dissertation in Electrical Engineering

John C. Cochran

doi:10.62791/19898

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A general theory of the slotted cylinder projector (SCP) transducer: a dissertation in Electrical Engineering

John C. Cochran

Doctor of Philosophy (PHD), University of Massachusetts Dartmouth

2018

DOI:

https://doi.org/10.62791/19898

Abstract

Electroacoustic transducers

Piezoelectric transducers

Electroacoustic piezoelectric transducers are used for underwater acoustics applications and there is a particular interest in compact low frequency source transducers. The dissertation addresses the theory for the Slotted Cylinder Projector(SCP) of bilaminar construction, a low frequency flexural mode device comprising a segmented piezoelectric driver formed by a series of tapered piezo-ceramic staves surrounded by a cylindrical passive shell with an axial slot. The dissertation improves upon current work that addresses the uniform wall SCP with a general theory that explains the performance of both the uniform wall SCP and the tapered wall SCP. Tapering the shell thickness is shown to offer benefits to the electro-mechanical acoustic performance. The second contribution to the field is a general approach for calculating the radiation impedance of radiating sources that have non-uniform velocity profiles. These two topics are addressed and then combined to provide a general theory for the analysis of the class of Slotted Cylinder Projector transducers.

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Title: A general theory of the slotted cylinder projector (SCP) transducer
Creators: John C. Cochran
ORCID: 0000-0003-2398-0761
Contributors: David A. Brown (Advisor) - University of Massachusetts Dartmouth, Department of Electrical and Computer Engineering
John R. Buck (Committee Member) - University of Massachusetts Dartmouth, Department of Electrical and Computer Engineering
Paul John Gendron (Committee Member) - University of Massachusetts Dartmouth, Department of Electrical and Computer Engineering
Corey Bachand (Committee Member) - BTech Acoustics (United States)
Number of pages: xv, 122 pages
Illustrations: illustrations
Table of contents: Chapter 1 : Background. The slotted cylinder projector ; Radiation impedance for the SCP sources with non-uniform velocity distribution -- Chapter 2 : Problem statement and approach. The slotted cylinder projector ; Radiation impedance for SCP sources with non-uniform velocity distributions -- Chapter 3 : Theoretical development of the in-air performance of the slotted cylinder projector (SCP) transducer. Geometry and description ; Assembly wall thickness, radii, and taper factors ; Neutral axis ; Transducer mass ; Displacement profiles and middle surface curvature ; Radial and circumferential velocity components ; Stress and strain in the transducer wall ; Kinetic energy and flexural mass ; Equations of state for the ceramic phase ; Voltage across electrodes and electric displacement ; Internal energy ; Flexural stiffness ; In-air resonant frequency ; Effective electro-mechanical coupling factor, keff ; Chapter 3 summary -- Chapter 4 : Radiation impedance for SCP transducers. The SCP as a simple source radiator ; Radiation impedance of SCP sources with non-uniform velocity distribution ; Chapter 4 summary -- Chapter 5 : Equivalent circuit model of the slotted cylinder projector. Description of equivalent circuit ; Number of Piezo-Ceramic bars, Nb ; Free capacitance, Ct ; Blocked Capacitance, Cₒ ; Dielectric loss resistor, Rₒ ; Electro-mechanical turns ratio, ɸ ; Mechanical, or flexural compliance, Cf ; Mechanical, or flexural mass, Mf ; Loss resistor, RL, and transducer efficiency ; Input admittance and impedance -- Chapter 6 : In-water performance parameters for the slotted cylinder projector (SCP). In-water resonant frequency ; Mechanical Qmw for the slotted Cylinder projector ; Drive voltage, Vd ; Directivity index, DI ; Transmitting voltage response, TVR ; Output sound pressure level, SPL -- Chapter 7 : Comparison of theory to measured results. Example 1 : A tapered wall SCP ; Example 2 : A uniform wall SCP ; Example 3 : A tapered wall SCP ; Chapter 7 summary -- Chapter 8 : Discussion. Source level vs taper ; Resonant frequency vs taper ; Bandwidth vs Taper ; Material and geometry sensitivity ; Impact of less ceramic on SCP performance ; Optimizing the tapered wall slotted cylinder projector -- Chapter 9 : Summary -- Bibliography.
References: Includes bibliographical references (pages 120-122).
Awarding Institution: University of Massachusetts Dartmouth
Degree Awarded: Doctor of Philosophy (PHD)
Degree in: Electrical Engineering
Academic Unit: Department of Electrical and Computer Engineering
Language: English
Resource Type: Dissertation
DOI: https://doi.org/10.62791/19898
Record Identifier: 9914424789001301