EP0114764A2 - Vorrichtung zur Reflexion von akustischen Wellen - Google Patents

Vorrichtung zur Reflexion von akustischen Wellen Download PDF

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Publication number
EP0114764A2
EP0114764A2 EP84400076A EP84400076A EP0114764A2 EP 0114764 A2 EP0114764 A2 EP 0114764A2 EP 84400076 A EP84400076 A EP 84400076A EP 84400076 A EP84400076 A EP 84400076A EP 0114764 A2 EP0114764 A2 EP 0114764A2
Authority
EP
European Patent Office
Prior art keywords
volume
wall
rigid wall
acoustic waves
rigid
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
EP84400076A
Other languages
English (en)
French (fr)
Other versions
EP0114764B1 (de
EP0114764A3 (en
Inventor
Bernard Fromont
René Reynier
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Thales SA
Original Assignee
Thomson CSF SA
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Thomson CSF SA filed Critical Thomson CSF SA
Publication of EP0114764A2 publication Critical patent/EP0114764A2/de
Publication of EP0114764A3 publication Critical patent/EP0114764A3/fr
Application granted granted Critical
Publication of EP0114764B1 publication Critical patent/EP0114764B1/de
Expired legal-status Critical Current

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Classifications

    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
    • G10K11/00—Methods or devices for transmitting, conducting or directing sound in general; Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
    • G10K11/18—Methods or devices for transmitting, conducting or directing sound
    • G10K11/20—Reflecting arrangements
    • G10K11/205—Reflecting arrangements for underwater use

Definitions

  • the reflection of acoustic waves according to an interface separating two media of impedances Z 1 and Z 2 is linked to a ratio Z I / Z 2 different from unity.
  • the invention relates more particularly to devices with an acoustic wave reflector interface of the "soft" type.
  • reflectors are known, the structure of which is made of a flexible and waterproof envelope which contains two rigid plates enclosing an airy structure made of metal wires.
  • These reflectors have the drawback of losing their deformability too quickly when they have to withstand a high hydrostatic pressure which is encountered at immersion depths of a few tens of meters.
  • the reflective interface risks losing its shape and can change position relative to the transducers mounted nearby, so that the expected phase shifts are modified.
  • the main object of the invention is a device for reflecting acoustic waves according to an interface separating a volume of viscoelastic material with gas cells from a material permeable to said acoustic waves used to isolate this volume from the external fluid medium of higher density, characterized in that said volume is applied against a rigid wall made of said permeable material; said wall being carried by a rigid support; a flexible closing element cooperating with said rigid wall to ensure the tightness of said device while transmitting to said volume the external hydrostatic pressure, in order to prevent the deformation and the change of position of the interface whose shape is imposed by said wall rigid.
  • the reflection device of FIG. 1 comprises upstream of the reflective interface 24 a rigid wall 21 comprising a flange 28.
  • This wall which takes the form of an open housing is, permeable to acoustic waves while serving as a means of sealing against the external fluid.
  • the wall 21 is made of a material transparent to incident acoustic waves such as an organic synthetic material.
  • the open case 21 can for example be made up of an assembly of glass fibers impregnated with polyester resin. After polymerization, a resistant and light shell is obtained. It is also possible to use for the housing 21 a material of acoustic impedance markedly greater than poCo, for example metal, but the thickness must satisfy certain conditions for transmission of the incident acoustic waves.
  • the stiffness provided by the housing 21 is sufficient to prevent any deformation resulting from the action of the hydrostatic pressure.
  • the casing 30 can overflow so as to cover the rim (28) of the housing 21 to which it is fixed by means of an adhesive 23, contributing to the sealing of the assembly
  • the casing 30 can cover the entire reflecting device of the flexible closing element which undergoes all the deformations which result from the crushing of the foam by hydrostatic pressure, but the presence of gaseous cells prevents packing which would undesirably modify the acoustic impedance used for r effectively deflecting incident acoustic waves.
  • the foam 20 reflects the acoustic waves.
  • Figure 3 shows the device of Figure 1 subjected to external hydrostatic pressure.
  • the hydrostatic pressure, symbolized by the arrows 32 is exerted in particular on the faces 27 and 29 of the reflector.
  • the casing 30 fully transmits the pressure to the viscoelastic foam 20, which transmits it entirely to the rigid casing 21.
  • the pressures exerted on its two main faces being the same, the casing does not deform when the hydrostatic pressure varies.
  • the foam 20 of thickness d is crushed.
  • the thickness d e is chosen so that is weak compared to ⁇ 1 c 1 , at the lowest frequency that we want to reflect with the reflector.
  • Ci is the reduced thickness of the foam 20 at the maximum depth for which the device according to the invention is intended, so that the thickness d must be chosen accordingly.
  • FIG. 4 illustrates an alternative embodiment of the device according to the invention where the rigid wall 21 is a simple plate fixed directly to the structure 26 by means of a support forming a mounting frame 110. Openings 112 are provided in the frame 110 , so that the external hydrostatic pressure can act on the face 29 of the device.
  • the face 29 belongs to a flexible closing element which envelops the foam 20 and which is sealed against the wall 21.
  • a soft reflector device can be provided, for example, with a sheet of piezoelectric material 31 placed between electrodes to perform the transducer function on transmission or on reception. This variant is illustrated in FIG. 5.
  • the reflector devices described above are particularly well suited to the production of passive listening antennas which include one or more hydrophones.
  • the hydrophones are located opposite a reflecting surface composed of a set of devices as described above.
  • the shortest distance separating each hydrophone from the reflecting surface is advantageously equal to ⁇ / 4 where ⁇ is the wavelength corresponding to the central frequency of the listening band of the hydrophones.
  • FIG. 6 illustrates an example of arrangement of the reflectors 41 and hydrophones 40, in a passive listening antenna using a reflective surface of cylindrical shape.
  • the reflectors 41 have an elementary reflective surface of square shape and the hydrophones 40 are located directly above the center of symmetry of each elementary surface.
  • the reflectors 41 are held contiguously on a base by means of stirrups 42 held by tie rods 43, for example of steel.
  • Figure 7 is a sectional view of the device of Figure 6.
  • the base 26 of the antenna being for example cylindrical
  • the reflectors 41 are curved to match the structure and are held contiguously by means of stirrups 42 retained by steel tie rods 43 on the base 26.
  • Holes 45 allow the water to exert hydrostatic pressure on the faces 29 of the reflector devices according to the invention.
  • FIG. 8 illustrates an example of an arrangement similar to that of FIG. 6, but where the reflectors 41 are triangular. It is obvious that other arrangements of reflectors and hydrophones can be adopted without departing from the scope of the present invention.

Landscapes

  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Acoustics & Sound (AREA)
  • Multimedia (AREA)
  • Transducers For Ultrasonic Waves (AREA)
  • Measurement Of Velocity Or Position Using Acoustic Or Ultrasonic Waves (AREA)
EP19840400076 1983-01-19 1984-01-13 Vorrichtung zur Reflexion von akustischen Wellen Expired EP0114764B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR8300753A FR2539541B1 (fr) 1983-01-19 1983-01-19 Dispositif a interface reflectrice d'ondes acoustiques
FR8300753 1983-01-19

Publications (3)

Publication Number Publication Date
EP0114764A2 true EP0114764A2 (de) 1984-08-01
EP0114764A3 EP0114764A3 (en) 1984-08-22
EP0114764B1 EP0114764B1 (de) 1987-09-02

Family

ID=9285062

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19840400076 Expired EP0114764B1 (de) 1983-01-19 1984-01-13 Vorrichtung zur Reflexion von akustischen Wellen

Country Status (6)

Country Link
EP (1) EP0114764B1 (de)
AU (1) AU2355484A (de)
CA (1) CA1239693A (de)
DE (1) DE3465809D1 (de)
ES (1) ES528948A0 (de)
FR (1) FR2539541B1 (de)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2204217A (en) * 1987-05-02 1988-11-02 Gec Avionics Acoustic reflector
EP0435753A1 (de) * 1989-12-29 1991-07-03 Thomson-Csf Akustischer Reflektor, geeignet für grosse Eintauchtiefen
EP0328931A3 (de) * 1988-02-18 1991-07-31 The B.F. Goodrich Company Schallwand mit federnden Röhren
EP0506529A1 (de) * 1991-03-29 1992-09-30 Thomson-Csf Richtantenne für akustische Niederfrequenzwellen
FR2720590A1 (fr) * 1994-05-31 1995-12-01 Thomson Csf Antenne acoustique passive absorbante.

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN115482805B (zh) * 2022-08-03 2025-10-31 中国船舶重工集团公司第七一九研究所 一种可调控水下声波反射声场的声学超表面

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2811216A (en) * 1954-04-28 1957-10-29 Harris Transducer Corp Acoustic baffle construction
US2884084A (en) * 1954-10-28 1959-04-28 Sussman Harry Acoustic panel
DE1815684A1 (de) * 1968-12-19 1970-06-25 Krupp Gmbh Reflektor fuer Wasserschall
FR2240813B1 (de) * 1973-08-16 1976-04-30 France Etat

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2204217A (en) * 1987-05-02 1988-11-02 Gec Avionics Acoustic reflector
GB2204217B (en) * 1987-05-02 1990-05-23 Gec Avionics Acoustic reflector
EP0328931A3 (de) * 1988-02-18 1991-07-31 The B.F. Goodrich Company Schallwand mit federnden Röhren
EP0435753A1 (de) * 1989-12-29 1991-07-03 Thomson-Csf Akustischer Reflektor, geeignet für grosse Eintauchtiefen
FR2656720A1 (fr) * 1989-12-29 1991-07-05 Thomson Csf Reflecteur d'ondes acoustiques pouvant fonctionner sous une forte immersion.
US5099457A (en) * 1989-12-29 1992-03-24 Thomson-Csf Acoustic wave reflector capable of working under deep submersion
EP0506529A1 (de) * 1991-03-29 1992-09-30 Thomson-Csf Richtantenne für akustische Niederfrequenzwellen
FR2674717A1 (fr) * 1991-03-29 1992-10-02 Thomson Csf Antenne acoustique basse frequence directive.
FR2720590A1 (fr) * 1994-05-31 1995-12-01 Thomson Csf Antenne acoustique passive absorbante.
US5600609A (en) * 1994-05-31 1997-02-04 Thomson-Csf Absorbent passive acoustic antenna

Also Published As

Publication number Publication date
CA1239693A (en) 1988-07-26
EP0114764B1 (de) 1987-09-02
EP0114764A3 (en) 1984-08-22
FR2539541A1 (fr) 1984-07-20
FR2539541B1 (fr) 1986-09-19
ES8503449A1 (es) 1985-02-16
ES528948A0 (es) 1985-02-16
AU2355484A (en) 1984-07-26
DE3465809D1 (en) 1987-10-08

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