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
  • G10K11/16—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
  • B63G—OFFENSIVE OR DEFENSIVE ARRANGEMENTS ON VESSELS; MINE-LAYING; MINE-SWEEPING; SUBMARINES; AIRCRAFT CARRIERS
  • B63G8/00—Underwater vessels, e.g. submarines; Equipment specially adapted therefor
  • B63G8/28—Arrangement of offensive or defensive equipment
  • B63G8/34—Camouflage

Definitions

• the present invention relates to a device for absorbing the acoustic energy emitted inside a ship's hull and, more particularly, to such a device designed to equip a submarine.
• the present invention also relates to a modular acoustic screen forming part of such a device. .
• the submarines are held with the greatest possible discretion so as to prevent their location by the opposing navies. This
• LO implies in particular their electromagnetic and acoustic "silence”.
• Acoustic emissions in particular, originate in particular from the many devices that are necessary for the operation of the submarine, even when it is stopped.
• the present invention therefore aims to provide a device for absorbing the acoustic energy emitted inside a ship's hull, which does not form a screen for heat transfer to the outside of the ship, through the shell of it.
• the present invention also aims to achieve a modular acoustic screen for such a device, which has the required thermal "transparency” and acoustic "opacity" while being of reduced weight and size, easy assembly and maintenance. , good impact resistance and reduced manufacturing cost.
• the bed is formed of a plurality of acoustic screens adjacent elementary modulars, each supported between two adjacent pairs.
• each elementary modular screen is fixed between two couples by at least one strap passed around the screen and secured at its ends by means of attachment to two adjacent couples.
• a bar can be associated with each strap to pinch an elementary modular screen between them and fix it on the two pairs.
• each elementary screen is fixed with the aid of columns protruding from some of the passages drilled in the screen, in order to press on the internal wall of the shell so as to define the predetermined distance separating this wall from the screen by wedging the screen between the base of these columns bearing against the shell and two adjacent pairs.
• the elementary modular acoustic screen used to form the bed takes the form of a parepelepipedal block of a porous material capable of absorbing acoustic radiation, this block being crossed by passages whose outlets are distributed on two opposite faces of the block.
• FIG. 1 is a partial perspective view of the hull of a ship equipped of the acoustic energy absorption device according to the invention
• - Figure 2 is a partial view, in perspective and in section, of an elementary modular acoustic screen forming part of the device according to the invention and its fixing means on the hull of the ship
• - Figure 3 is a view similar to that of Figure 2 and shows another embodiment of the means for fixing an elementary modular acoustic screen forming part of the device according to the invention.
• FIG. 1 of the drawing -annexed -where-1-a part of the hull 1 of an underwater ship has been represented.
• This shell 1 is then generally cylindrical and it is supported by "pairs" 2 taking the form of circular beams with T-section, welded to the internal wall of the shell (around a quarter of these beams are shown in FIG. 1 ).
• the shell 1 is doubled, at a distance E from its internal wall, by a bed made of an acoustically absorbent material of thickness D, this bed being formed by a mosaic of elementary modular screens 3 joined together.
• a bed made of an acoustically absorbent material of thickness D this bed being formed by a mosaic of elementary modular screens 3 joined together.
• beams 2 to fix the screens 3 to the
• FIG. 1 An essential characteristic of the invention thus appears in FIG. 1, namely the presence of a space of radial thickness E between the bed consisting of screens 3 and the internal wall of the shell 1, this space communicating with the atmosphere of the submarine thanks to passages 4 crossing the thickness of each screen.
• these passages 4 are of cylindrical shape and completely pass through the thickness D of the screen.
• the outlets of these passages on two opposite faces of the screen are preferably regularly distributed over these surfaces, for example in staggered rows.
• air can circulate through the screen through the passages 4, either in one direction or the other, and in the annular space of thickness E situated between the screens constituting the bed and the inner wall of the submarine (this air circulation taking place in the direction of the arrows shown in Figure 1).
• Air heated inside the submarine by engines and other devices operating in it, can thus, by free convection, circulate against the hull of the ship to exchange calories with the sea water located beyond the hull, an exchange which has the effect of cooling this air, thus contributing to its conditioning.
• any internal acoustic emission in the submarine is largely absorbed by the bed of acoustic screens 3 fixed to the couple 2, without the presence of this bed disturbing the necessary heat exchange
• FIG. 2 shows a first embodiment of these fixing means, which essentially comprise a strap 5 provided ⁇ each of its ends with means for hooking on wings 6 opposite two adjacent pairs 2.
• These means may include a bracket 7 hooking on the underside of a wing of a couple 2 (from the point of view of figure) bracket integral on the one hand with one end of the strap 5 and, on the other part, a welded nut 8 provided to cooperate with a screw 9.
• the fixing means may further comprise a bar 10, constituted for example by a metal pipe with crushed ends and pierced with a hole. We pass the screw 9 in this hole and we tighten this screw in the nut 8, to pinch the screen 3 between the bar and the strap. The screen is thus securely fixed on two adjacent pairs, as shown in FIG. 2.
• FIG. 3 shows another embodiment of the means for fixing an acoustic screen.
• REPLACEMENT SHEET 3 The screen is notched, as shown, along two edges to adapt complementally to the profile of two wings 6 of adjacent couples. Wing cases are provided on their underside with a double-sided adhesive tape 12 which allows the bonding of two surfaces facing the screen and these wings. A joint cover 13 'è section in T closes the interstice torque / elementary screen. Columns 11 passed in some of the passages 4 drilled in the screen 3 are pushed in case of passages so as to come into abutment on the hull 1 of the ship. Columns can be formed simply using the cores removed from the passages 4 drilled in the screen.
• balusters can be provided, for example at the four angles of a screen and in the vicinity of its central part, to thus completely support the latter away from the hull so as to provide a space of free circulation for the air to be cooled by heat exchange with the sea water located the other side of the hull.
• an acoustic absorption device capable of reducing the “air noise” of the submarine from 10 to 15 decibels
• elementary acoustic screens were produced in a bed of mineral fibers, glass or rock , or in a foam bed of synthetic materials such as polymers.
• a preferred material is the polyimide foam called Illmid sold by the company ILLBRUCK (RFA).
• Illmid sold by the company ILLBRUCK (RFA).
• REPLACEMENT FE UI dimension 500 x 500 x 200 (in mm), the screen being placed 100 mm from the shell, cumulative surface of the passage sections / screen surface: 40%, density of the material constituting the screen: 10 kg / m 3
• This material is satisfactory in other respects in particular as regards its temperature and impact resistance, as regards the toxicity of the decomposition products and the fumes which are emitted in the event of combustion, important considerations very particularly in the case of a material intended to be installed in a closed enclosure such as the hull of a submarine.
• the ratio d / D of the diameter d of a cross section of a passage 4 to the thickness D of the screen and the ratio s / S of the cumulative surface s of the sections of passages 4 To the surface S of a faces of the screen where these passages open are parameters on which the skilled person can act to adapt the thermal and acoustic performances of the device according to the invention to such or such specification laid down by a specification.
• the s / S ratio can vary significantly, from 30 to 50% for example.
• the d / D ratio may be between 3 and 10, for example.
• the invention is not limited to the embodiments described and shown which have been given only by way of example. Thus, one could substitute other screens for the elementary screen described above, pierced with cylindrical passages.
• any arrangement making it possible to establish passages of any shape, with an evolving section and / or with rectilinear axes or not, through the thickness of a block made of an acoustically absorbent material, could be adopted to make the elementary screens constituting the device according to the invention.
• the invention is not limited to improving the acoustic discretion of an underwater ship and can find application in surface ships in which only part of the hull is in contact with the water of sea.

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• Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• Acoustics & Sound (AREA)
• Multimedia (AREA)
• Mechanical Engineering (AREA)
• Aviation & Aerospace Engineering (AREA)
• Soundproofing, Sound Blocking, And Sound Damping (AREA)
• Measurement Of Velocity Or Position Using Acoustic Or Ultrasonic Waves (AREA)

Applications Claiming Priority (2)

Publications (1)

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ID=9398495

Family Applications (1)

Country Status (4)

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Family Cites Families (4)

• 1990
  • 1990-07-09 FR FR9008675A patent/FR2664418B1/fr not_active Expired - Lifetime
• 1991
  • 1991-07-09 WO PCT/FR1991/000554 patent/WO1992000874A1/fr not_active Application Discontinuation
  • 1991-07-09 CA CA 2066241 patent/CA2066241A1/en not_active Abandoned
  • 1991-07-09 EP EP19910913468 patent/EP0491034A1/de not_active Withdrawn

Non-Patent Citations (1)

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