Power Transducers for Sonics and Ultrasonics: Proceedings of the International Workshop, Held in Toulon, France, June 12 and 13, 1990 PDF
Preview Power Transducers for Sonics and Ultrasonics: Proceedings of the International Workshop, Held in Toulon, France, June 12 and 13, 1990
Power Transducers for Sanies and Ultrasonics B. F. Hamonic O. B. Wilson J.-N. Oecarpigny (Eds.) Power Transducers for Sanies and Ultrasonics Proceedings of the International Workshop, Held in Toulon, France, June 12 and 13, 1990 With 215 Figures Spri nger -Verlag Berlin Heidelberg New York London Paris Tokyo Hong Kong Barcelona Dr. Bernard F. Hamonic Dr. Jean-Noel Decarpigny Acoustics Laboratory, ISEN, 41 bd. Vauban, F-59046 Lille Cedex, France Dr. Oscar B. Wilson us Naval Postgraduate School, Monterey, CA 93943, USA Program chairman B. Tocquet, Thomson Sintra ASM, Valbonne, France Scientific Committee O. B. Wilson, Chairman, NPS, Monterey, CA, USA D. Boucher, GERDSM, DCAN, Toulon, France J.-N. Decarpigny, ISEN, Lille, France B. F. Hamonic, ISEN, Lille, France Organizing Committee M. Daux, ISEN, Lille, France B. F. Hamonic, iSEN, Lille France J.-C. Debus, ISEN, Lille France J.-N. Decarpigny, ISEN, Lille France The sponsorships from: - Direction des Recherches, Etudes et Techniques (DRET), - Thomson Sintra ASM, - Schlumberger Etudes et Production, - Toulon-Var-Technologies (TVT), - Centre National de la Recherche Scientifique (CNRS), - Institut Superieur d'Electronique du Nord (ISEN) are greatly acknowledged. ISBN-13:978-3-642-76273-4 e-ISBN-13:978-3-642-76271-0 DOl: 10.1007/978-3-642-76271-0 This work is subject to copyright. All rights are reserved, whether the whole or part of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfilms or in other ways, and storage in data banks. Duplication of this publication or parts thereof is only permitted under the provisions of the German Copyright Law of September 9, 1965, in its current version, and a copyright fee must always be paid. Viola tions fall under the prosecution act of the German Copyright Law. © Springer-Verlag Berlin Heidelberg 1991 Softcover reprint of the hardcover 15t edition 1991 The use of registered names, trademarks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use. 2156/3140-543210 Preface This volume contains the Proceedings of the International Workshop on Power Transducers for Sonics and Ultrasonics, which was held in the Hotel Helios, He des Embiez near Toulon, France, on June 12 and 13, 1990. This Workshop was the second one in a series; the first one was held in Lille in 1987. The main objective of this Workshop was first to expose the trends and needs in the design, analysis, construction, and testing of low-frequency, high-power transducers for sonars, for oceanographic and petroleum-finding (geophysical) ap plications, and for macrosonics, and second to stimulate an exchange of knowledge and experience between researchers and industrialists from various countries who are involved in this multidisciplinary field. The scientific program included 18 invited contributions distributed amongst seven sessions and a poster session, and there were 100 participants from around the world. The main topics of the sessions were: general trends, flextensional transducers, interactions in arrays, magnetostriction transducers, other transducing mechanisms, electronics, and measurement methods. The common theme for all sessions was summed up by three questions: What is the state of the art? What are the prospects for development? Where are we and where should we be going in the next five years? Emphasis was focused on the second and third questions. The editors are grateful to the authors and attendees for their active participa tion, and they hope that the reader of these proceedings will find a lot of useful information here. They also wish to thank everyone who helped in the numerous tasks connected with this venture. Special mention has to be made of Miss M. Daux and Mrs. E. Litton (IS EN Lille) for their constant and kind help from the beginning of the project to the very end of the editing. The editors are also grateful to the publishers and their staff, and Dr. H.-U. Daniel, who exercised patience in waiting for the manuscript. Lille, France B.F. Hamonic September 1990 GB. Wilson f.-N. Decarpigny Contents Introductory Lecture By B. Tocquet ........................................ 1 1. Transducer Needs for Low-Frequency Sonar By R.W. Timme, A.M. Young, and J.E. Blue (With 9 Figures) 3 2. Transducer Needs for Oceanography By R. Person ......................................... 14 3. Transducer Needs for Petroleum Acoustics By B. Froelich (With 8 Figures) ............................ 22 4. Transducer Needs for Macrosonics By J.A. Gallego-Juarez (With 9 Figures) 35 5. Class IV Flextensional Transducers By G. Bromfield (With 14 Figures) ...................... :... 48 6. The Ring-Shell Flextensional Transducer (Class V) By G.W. McMahon (With 18 Figures) .. . . . . . . . . . . . . . . . . . . . . . . 60 7. Transducers for Great Depths By P. Dufourcq, J. Adda, M. Letiche, and E. Sernit (With 10 Figures) " 75 8. Physics of Array Element Interaction Phenomena By R.T. Richards, J.B. Blottman ill, and B. McTaggart (With 18 Figures) 86 9. Numerical Modeling of Array Interactions By G.W. Benthien (With 12 Figures) . . . . . . . . . . . . . . . . . . . . . . . .. 109 10. Magnetostrictive Materials By D. McMasters (With 5 Figures) .......................... 125 11. Modeling and Characterization of the Magnetostrictive Coupling By F. Claeyssen, R. Bossut, and D. Boucher (With 6 Figures) .. . . . . .. 132 12. A Magnetostrictive Transducer Design By G.A. Steel and J.R. Oswin (With 9 Figures) 152 13. Magnetohydrodynamic and Thermoacoustic Mechanisms for Generation of Sound in Seawater By S.L. Garrett and T.B. Gabrielson (With 7 Figures) ............. 162 VIII 14. A Low-Frequency, Tow-Powered Sound Source By J.E. Blue, A.L. Van Buren, and LT P.A. Semper (With 9 Figures) 178 15. Electronic Needs for High-Power Transducers By G.G. Dixon and S.R. Leyland (With 16 Figures) 186 16. Electronic Systems Modeling By S. Faure and J.M. Capron (With 24 Figures) ................. 203 17. Calibration of Underwater Acoustic Transducers at NRL/USRD By A.L. Van Buren and J.E. Blue (With 22 Figures) .............. 221 18. Measurement Methods for Low-Frequency Transducers By C. Giangreco, S. Faure, and J.F. Rossetto (With 19 Figures) 242 19. Poster Session Abstracts 257 SUbject Index ........................................ 269 Introductory Lecture B. Tocquet Thomson Sintra Activites Sous Marines, Route des dolines, Parc d'activite de Valbonne, B.P. 38, F-06561 Valbonne Cedex, France 1 OBJECTIVES REMINDER The objectives are: -to present the needs and prospects related to the study, design and reactivation of low frequency, high power sonic sources used for sonar, to ocean and oil research and to macrosonics. -to favour exchanges between research bodies and industrialists involved in the field. The papers presented during these two days should enable to answer, at least partially, the three following questions: -what is the current state of the art? -what are the development prospects? -which improvements can be expected within the next five years? 2 TOPICS DEALT WITH The topics to be dealt with are broken into seven sessions: -what are the needs for low frequency sonar, oceanography, 011 research and macrosonics, -a specific solution: the flextensional transducers, the limitations involved by immersion, -interactions between typical transducers when they are grouped to form arrays, -the magnetostrictive materials, -other transduction mechanisms, -what are the needs for power electronics and systems design, -acoustic measurement methods. A poster session dealing with the whole field will be held on Tuesday evening. 2 The first workshop, organized in Llile 3 years ago, had been a real success. This promises to be as successful because: - the topic has never been of such Interest than today, In the civilian field (offshore and well 011 research, ocean tomography, macrosonlcs) as well as in the military field (stimulation of towed or moored linear arrays, counter measurements), - the number, the geographical origin and the quality of the participants and Invited speakers witness the interest for this topic, but also the quality of the organizers, - the rising costs of research and development (R& D) and the stability, not to say the decrease, in some budgets are elements that should Incite us to collaborate tightly and to take advantage of all the possible synergies between users. All these elements should stimulate exchanges between participants and make this workshop a real success. Now, let's hope that the weather is not going to be too fine. I think that the organizers are terribly self-confident; organizing such a 'serlous' workshop in such a heavenly place, what a riskl 1. Transducer Needs for low-Frequency Sonar R. W. Timme, A.M. Young, and J.E. Blue Naval Research Laboratory, Underwater Sound Reference Detachment, P.O. Box 568337, Orlando, FI32856-8337, USA The continued advances in the acoustic quieting of submarines will necessitate the use of active sonar as an adjunct to the traditional passive sonar as a means of detecting submarines. Therefore, there is a growing need for transducers that produce sound underwater at frequencies below 1000 Hz. However, reality is such that It Is very difficult to design for low frequency, high power, and high efficiency and still maintain a device possessing reasonable size, weight, reliability, and cost. Different design approaches and transducer types are discussed and compared. 1.1 INTRODUCTION The continued advances in the acoustic quieting of submarines (1.1-1.3) will necessitate the use of active sonar as an adjunct to the traditional passive sonar as a means of detecting submarines. Therefore, there is a growing need for transducers that produce sound underwater at frequencies below 1000 Hz. However, reality Is such that it is very difficult to design for low frequency, high power, and high efficiency and still maintain a device possessing reasonable size. weight, reliability, and cost. Different design approaches and transducer types are discussed and compared. 1.2 FACTORS DRIVING LOW-FREQUENCY SONAR TRANSDUCER NEEDS Given that there is a need for active acoustic projection. any competent acoustician can tell you that It generally means operating at frequencies below 1 kHz for reasons of range, resolution, and scattering. Figure 1.1 shows sound scattering intensity from a rigid cylinder at normal Incidence to the side as a function of ka where k is 21t divided by the wavelength of the Incident sound and a Is the radius of the cylinder (1.4). Assuming a 5 m radius as somewhat typical for a submarine and seeing from Fig. 1.1 that frequencies where ka ~ 1 give good sound scattering, one might conclude that frequencies above 100 Hz might be of Interest In submarine detection at normal Incidence. 4 1.0 a w 0:: .75 ~ ..: () (f) ~ .50 iii z ~ ?; .....:J .25 I- 0 I- 3 4 5 6 ka Fig. 1.1 Scattering of sound from a rigid cylinder of radius a(k = 2 nf')..) 1.3 LIMITING FACTORS ON HIGH-POWER, LOW-FREQUENCY SONAR PROJECTORS Transducers designed to produce underwater sound at low frequencies generally have small dimensions compared to the wavelength of the sound produced (')..»D). For illustration purposes, let us consider a pulsating sphere of radius a where ')..»a. Figure 1.2 shows the relationships that are important for low-frequency radiation. Pressure at the surface of the sphere: pea) == pc vn (ka)2 -ipc vn ka vn = velocity of surface of sphere. Z=£ =R,+IX, Total radiation Impedance: vn Rr == pc (4 n a2) (ka)2, Xr == - 00 (4n a3). Source level in the water 2 referenced to 1 meter from the sphere: ip\Jm = oopU = 00 pX 4n 4n U = volume velocity, X = volume displacement. Acoustic power radiated: P = vn2 R, = p4cn p2 Fig. 1.2 Relationships for radiation from a uniformly pulsating sphere of radius a where ka « 1, p and c are the density and the sound velocity in water These relationships for power and source level are plotted in Fig. 1.3. Note that at 100 Hz, a volume displacement of 1000 cm3 (0.001 m3) will radiate 104 watts of acoustic power and give a source level of 211 dB re 1 IlPa at 1 m. However, as can be seen from Fig. 1.4 for ')..»a, the total input power necessary to supply the acoustic power Is controlled primarily by the reactive impedance, and the resistive component of the Impedance is very low. Thus, the basic problem Is one of poor acoustic loading due to very long acoustic wavelengths In water at low frequencies. Simply stated, this means the transfer of mechanical power at the surface of the radiator to the water under the form of radiated acoustic power is very Inefficient. Since the
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