Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
  • B63B—SHIPS OR OTHER WATERBORNE VESSELS; EQUIPMENT FOR SHIPPING 
  • B63B1/00—Hydrodynamic or hydrostatic features of hulls or of hydrofoils
  • B63B1/32—Other means for varying the inherent hydrodynamic characteristics of hulls
  • B63B1/34—Other means for varying the inherent hydrodynamic characteristics of hulls by reducing surface friction
  • B63B1/38—Other means for varying the inherent hydrodynamic characteristics of hulls by reducing surface friction using air bubbles or air layers gas filled volumes
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
  • Y02T70/00—Maritime or waterways transport
  • Y02T70/10—Measures concerning design or construction of watercraft hulls

Definitions

• the present invention concerns a ship having a resistance-reducing void in the flat bottom portion of the ship, wherein the lower part of the void is filled with water while the upper part is filled with air.
• the wet surface is the part of the hull that at zero speed is in contact with the surrounding water. This can take place by the fact that a part of the flat bottom surface is carried out as a void, which partly is filled with air.
• the lower part of the void is filled with water while the upper part is filled with air.
• the upper part is denominated air chamber.
• the surface separating the air from the water is denominated the interface. Because of the advance of the ship, a part of the air will be carried away by the subjacent water flow. The outflowing air then has to be compensated with new supplied air to the air chamber, which suitably takes place in the fore edge and in the upper part of the air chamber.
• the underwater hull and the void have to have a well adapted shape in order not to give rise to separation and turbulence. Separation, turbulence in the void and wave generation in the air chamber may otherwise
• the ship When the ship moves in high sea, it may be rolling in the transverse direction, i.e., a reciprocating rotary motion around a longitudinal axis in the centre line of the ship, or pitch motion, i.e., reciprocating rotary motion around a horizontal transverse axis
• Air outflow upon rolling can to a certain extent be reduced by means of division of the void using longitudinally
• the main object of the present invention is to provide a ship, which has means at the entrance to the void, and which reduces and in the best case
• a ship according to the present invention which essentially is characterized in that means is arranged for directing the water flow from the front portion of the ship in to the front part of the void, that said means consists of a curvature, which begins at the bottom portion of the ship, suitably from a horizontal level, ww
• an air gap in the form of an opening is situated in the curvature or in, or at, the inclined plane, that a number of air-generating means are arranged for supplying air to said air gap so that an air flow is created from the air gap to the space under the curvature or the inclined plane .
• US patent 6,575,106 Bl shows a solution the object of which is something entirely different than according to the present invention.
• it is tried to utilize the negative pressure that is formed of the curvature at the forebody to suck in air from a passive chamber through a gap. Then, this air should in some way not mentioned be brought to increase in pressure by the air being retarded. This increased pressure should then fill the cavity with air.
• the idea is accordingly that the speed of the ship should be utilized for filling the air chamber. Sounds as a perpetual motion machine that will not work.
• the invention is based, as
• the entrance to the void, the sharp edge is replaced by a curvature as well as by a principally flat plane inclining in the longitudinal direction of the ship.
• the curvature and the inclined plane control the water flow into the void.
• the curvature suitably begins from a horizontal level that may be the flat bottom of the base line and preferably constitutes the end of a bulb at the forebody.
• the end of the curvature and the inclined plane should principally have the same angle to the horizontal plane. This angle should also be smaller than the angle that causes separation at the speed in question.
• the curvature which may be a circular arc, should be selected so that it does not cause separation.
• Curvature and inclined plane may be selected as
• An extra air chamber situated afore is accordingly formed above the curvature and/or the inclined plane and the above mentioned air-generating means are fore air chambers to the above mentioned air gap.
• the air flow will create an air stratum under the inclined plane.
• the device affords several important advantages.
• the air stratum under the inclined plane will further decrease the wet surface.
• the air stratum under the inclined plane will equalize pressure differences so, that when the interface is reached, this can take place without the formation of greater waves .
• This solution may then be applied to higher speeds and when the interface because of high sea is forced to be located higher up.
• the Coanda effect is affected by the air stratum under the inclined plane.
• a negative pressure may be created in front of the gap by the fact that the curvature is increased until the radius of curvature becomes zero. In such a way, the air flow through the air gap can be increased.
• Figs. 1, 1A, IB, and 1C schematically show a ship having a device according to the invention applied at the ship's fore part of the bottom portion of the hull,
• Figs . 2 and 3 show enlarged the front portion of the void with the extra air chamber
• Figs. 4-6 show different examples of alternative solutions of air supply
• Figs. 7-8 show section views of air gap and ducts.
• Fig. 1 shows a first embodiment example of the invention.
• the figure shows a vertical section in the centre line of a ship provided with a device according to the invention.
• An extra fore air chamber 8 is filled with air in a conventional way by means of fans or pumps 27 through duct 26.
• the air flows out through an air gap 7 and the air flow follows the underside of an inclined plane 6 up to a large air chamber 40 in a void 4 under the ship.
• the pressure will then increase in this air chamber and the interface between air/water will be lowered all the way down to the level where balance of the pressure occurs, or where there is discharge of air along the edges of the void and balance occurs between outflow and inflow of air.
• the ship is moving little and is lying on near even keel, i.e., without trim, said point of balance will occur with the interface very near the base line. However, if the ship is in motion, balance of air flow will occur on higher levels.
• Fig. 1A shows an alternative embodiment to Fig. 1, where balance of the air pressure can be obtained on a higher level of the interface without there being any- air discharge.
• the shape of the forebody is of vital importance.
• the forebody should give a water flow with streamlines that are as close as possible parallel to the centre line. This flow will then, when it flows from the top downward and when it reaches the underside of, e.g., a bulb 29, create a negative pressure. Said negative pressure is further augmented when the water flow moves upward along the above mentioned curvature 5. This means that also with a relatively low positive pressure in the air chamber 8, the air will be sucked/pressed out through the air gap 7.
• Fig. IB shows an alternative embodiment to
• Fig. 1A where the same effect as has been described above can be achieved even if the hull form and the curvature have not created a sufficient negative pressure under the curvature.
• the aft end of the inclined plane 6 now reaches all the way up to the ceiling of the void 4 and closes tightly.
• the extra fore air chamber 8 is filled with air in a conventional way by means of fans 27 or pumps through the duct 26.
• the air flows out through the air gap 7 and the air follows the underside of the inclined plane 6 up to the large air chamber in the void 4.
• the pressure then aims to increase in this air chamber but the void 4 has now its own air conduit duct 54 where fans 53 can suck out superfluous air, so that a desired level of the interface is obtained. If the ship is subjected to large motions with large amounts of leaking air along the edges of the void, this leaking air may also be compensated by
• Fig. 1C shows an alternative embodiment to
• FIG. IB A transverse bulkhead 50 has been introduced in the front air chamber 8.
• the air conduit duct 54 having the fan 53 in Fig. IB is now moved to the space astern of the transverse bulkhead 50 and is designated in Fig. 1C as duct 51 having fans 52.
• the inclined plane 6 has now an opening 9 in its aft side. The same function and
• FIG. 2 shows an enlarged picture of the fore air chamber 8, with the inclined plane 6 and the opening 9 in the aft side of the inclined plane.
• Fans 27 deliver air through the duct 26 to the chamber 8.
• An air flow 10 runs from the chamber 8 through the gap 7 and forms an air layer that follows the underside of the inclined plane 6.
• Fig. 3 shows an enlarged picture of an example of the fore air chamber 8.
• the void 4 is upwardly limited by the ceiling 1 of the void and downwardly by the lower edge of the void, in this example the so-called base line 2.
• the curvature 5 has started horizontally on the base line 2 somewhat astern of the end of, for instance, a bulb.
• the end 5A of the curvature has primarily the same angle to the horizontal plane as the inclined plane 6.
• the front/lower end portion 6A of the inclined plane is placed somewhat in front of and above the aft end portion 5A of the curvature. In such a way, the gap 7 will give the air flow 10 an astern direction along the underside of the inclined plane 6.
• the water flow 23 coming from the stem follows the curvature 5 and will then be separated from the inclined plane by said air flow 10.
• the pressure of the water flow 28 corresponds to the pressure of the air flow 10
• the large air chamber in the void is reached without any major wave amplitudes 30 having been formed on the interface 3.
• FIG. 4 a variant is shown wherein the air gap 7 extends through the inclined plane 6 without any curvature and an air duct 26 provided with fan 27.
• Fig. 5 shows an air gap 7 formed directly in the end of an air supply duct 26 provided with a fan 27 and without the presence of any extra fore air chamber.
• Fig. 6 shows an air opening 9 situated at the upper end portion of the inclined plane 6, however not farthest up, while an outlet slot 7 for air is situated further forward on the inclined plane 6, leading from an air chamber 8.
• Figs. 7 and 8 show connection of one or more air ducts 26, which reach up to a said slot-shaped air gap 7, which extends transversely to the length extension of the ship.

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Citations (8)

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• 2015
  • 2015-01-13 SE SE1550022A patent/SE539235C2/sv unknown
• 2016
  • 2016-01-07 WO PCT/SE2016/050004 patent/WO2016114705A1/en active Application Filing
  • 2016-01-07 CN CN201680005786.3A patent/CN107428394B/zh active Active
  • 2016-01-07 JP JP2017555206A patent/JP6808263B2/ja active Active
  • 2016-01-07 KR KR1020177020403A patent/KR102463807B1/ko active IP Right Grant

Patent Citations (8)

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