JP2015520073A - Method and apparatus for reducing hydrodynamic water resistance of ships - Google Patents

Abstract

The present invention relates to a method and apparatus for reducing water resistance of a ship. In particular, the present invention relates to a method for reducing a bow wave generated during navigation by a ship's trunk (2). This method is characterized in that a gas / water mixture is produced before the bow (4) of the fuselage, preferably the gas is air. The present invention is also directed to a device for reducing the bow wave of a ship during navigation, which device releases air under pressure. This compressed air is discharged into the appropriate area at an appropriate angle in front of and around the bow (4) of the ship.

Description

  The present invention relates to a method and apparatus for reducing water resistance of a ship. In particular, the present invention relates to a method for reducing a bow wave generated during navigation by a ship's trunk.

  Ships are known to generate bow and stern waves during navigation. These waves make a major contribution to the overall resistance, which increases in square with increasing speed square. The maximum speed of the ship basically depends on the length of the fuselage and the distance from the bow wave to the stern wave. When the bow and stern waves overlap, the ship is “captured” in it and cannot be faster, regardless of engine power.

  Overcoming these hydrodynamic resistances has two main consequences: first, a powerful and correspondingly expensive engine, and second, the fuel consumption that increases with it. It is. Fuel accounts for almost half of the operating costs of ships. It is therefore particularly important to reduce such hydrodynamic resistance.

  Attempts have been made to achieve this with a special hull and bow shape. One example is the well-known spherical bow structure. It is known that the spherical bow is optimized for a given level, for example in certain loading conditions.

  However, this solution is not entirely satisfactory. This is because the spherical bow is effective only at a specific speed and a specific loading state (for example, when full). The reduction in resistance usually does not exceed 10% calculated on the forward and return paths, even under ideal conditions. A spherical bow can even increase resistance just by protruding it partially from the waterline.

  It is an object of the present invention to provide an effective system for overcoming the limitations of the prior art as described above and reducing the hydrodynamic resistance of ships. In particular, the present invention aims to reduce bow and stern waves, thereby reducing the overall resistance of the vessel during navigation.

  The idea underlying the present invention is to reduce the bow and stern waves generated during navigation by adding gas to the water in front of the bow, preferably by mixing air.

  Mixing is formed at an appropriate distance in front of the bow and at an appropriate depth relative to the water surface. The position of mixing depends on buoyancy and speed. For most practical applications, a distance of 0.1 to 30 meters is sufficient between the mixing formation before the bow and the bow itself. This can be achieved by adjustable movable nozzles. These nozzles are controllable in order to emit air in front of the bow within a defined range of travel and angles with respect to the water surface. For example, each nozzle disperses the air jet under a defined angle from the lower surface of the ship to the water surface within a certain angle in the direction of travel.

  One embodiment of the invention consists in injecting air through a sleeve that can be retrofitted around an existing spherical bow. This sleeve with an adjustable air nozzle introduces an air jet into the water along the lower fuselage, on the one hand in the direction of travel, or at the same time in the direction opposite to the direction of travel. This results in a significant further friction reduction.

  It is preferred that the apparatus pushes the gas into the water by pressure. The gas used should have a lower viscosity than water, especially air for practical reasons.

  By this invention, the static pressure with respect to a bow is reduced significantly, the friction in a ship wall is reduced, and a bow wave and a stern wave are relieved.

1 is a side view of a ship with a swivel device attached to the bow according to the present invention. It is another schematic side view which shows a ship provided with the apparatus of FIG.

  Reference numeral 1 schematically represents a ship 1 including a fuselage 2, a waterline 3 having a floating region 10, and a bow 4. Stern 5 (not shown in this diagram). In addition, the present invention can be applied to any large vessel. Therefore, the use of the term “ship” in the following description is representative of all types of ships.

  In one preferred embodiment, the air jet is injected into the water in the opposite direction of travel, i.e., it remains in the water until the bubbles formed are just before the stern of the ship. Thereby, the friction relaxation effect acts on the entire length of the body.

  It is fixed in the form of a link so that the swivel arm 9 obtains an appropriate diving depth depending on the navigation speed and / or load capacity of the ship. The change of the diving depth of the swivel arm 9 is controlled electronically.

  In FIG. 3a, by means of an adjustable nozzle, under a selectable angle α in the forward direction in the direction of travel X and at the same time under a selectable angle δ in the direction −X opposite to the direction of travel, It shows how air is injected.

  The same situation is shown in side view in FIG. The air can be selected by an adjustable nozzle within the range defined by the angles γ, γ 'under the angle β selectable forward in the direction of travel, and at the same time, the selectable angle in the direction opposite to the direction of travel Injected under ε.

  An embodiment is shown, in which an adjustable air supply is attached to the bow by one or more sleeves or belts C. Magnetic mounting is also possible. The distance between the air inlet and the bow varies between 0.1 and 30 meters. As can be seen in FIG. 3b, the air supply device may be attached directly to the bulbous bow.

Claims (15)

  Reduces bow waves on ships by creating a mix of low-viscosity gas and water in front of the bow injected at a variable angle relative to the ship's direction of travel and at a variable angle with respect to the ship's waterline how to.   The method according to claim 1, wherein the direction of the gas intake part has an acute angle with respect to the traveling direction of the ship and an acute angle with respect to the waterline of the ship.   The method according to claim 1, characterized in that the angle of gas delivery is variable and can be changed during navigation.   The method according to claim 1, characterized in that the mixing is generated at an appropriate depth with respect to the water surface with an appropriate spacing in front of the bow.   Method according to claim 2, characterized in that the interval and depth of the water / gas mixture formation varies depending on the operating conditions, for example depending on the buoyancy and / or speed of the ship.   6. A method according to any one of claims 1 to 5, wherein the distance between the mixing formation in front of the bow and the bow itself is 0.1 to 30 meters.   7. A method according to any one of the preceding claims, wherein the mixing is generated by a stream of bubbles at a suitable pressure and sent into the water before the bow of the ship.   The method according to claim 7, wherein the bubble streams contain bubbles of different sizes.   A method according to any one of the preceding claims, wherein the gas is air.   In a device for reducing the bow wave, the gas under pressure, preferably air, is moved by the device at a variable angle relative to the direction of travel of the ship and at a variable angle with respect to the waterline of the ship, around the bow of the ship. A device characterized in that it is injected within an appropriate range, thereby producing a mixture consisting essentially of gas and water.   11. An instrument according to claim 10, characterized in that the gas discharge is adjustable and the angle of gas delivery is variable and can be changed during navigation.   11. A device according to claim 10, characterized in that the discharge device for releasing the gas is adjustable so that mixing is produced at a suitable depth with a proper spacing in front of the bow. .   11. Device according to claim 10, characterized in that it has a control for adjusting the discharge device depending on operating conditions, for example depending on the buoyancy and / or speed of the ship.   14. A device according to any one of claims 10 to 13, characterized in that the distance between the mixing formation in front of the bow and the bow itself is 0.1 to 30 meters.   15. A device according to any one of claims 10 to 14, characterized in that the mixing is produced by a bubble stream from a compressor of suitable pressure.

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