EP0260395B1 - Icebreaking ship - Google Patents

Description

The invention relates to an ice-breaking ship with a pontoon-shaped fore ship lying above the water line, the side walls running parallel to one another and a flat and strongly inclined forward or arched forward or backward in the underwater ship, which extends over the entire width of the ship or which is arched downwards from front to back has a bent end face, the side edges forming the greatest width of the underwater ship penetrating the water lines which are narrowing on the bow of the ship behind them.

In ships with traditional ice-breaking ship shapes with pointed bends, very high external forces are introduced horizontally into the ice surface via the ship's outer skin, especially in the waterline area of the wedge-shaped bow water lines and the front shoulders of the ship shape, the ice surface being destroyed by compression and bending fractures. The high external forces, especially in these critical outer skin zones, lead to very high friction force components which counteract the bending fracture of the ice surface and the propulsion of the ship.

In ships with a favorable bow shape for ice breaking, break lines are created in the ice in front of the ship, which run transversely to the longitudinal axis of the ship and thus ice floes are obtained which initially have a width that corresponds to the width of the hull. These ice floes are pressed under the hull, broken in half at a certain depth and as planned then led away to the sides. In this process, the ice floe is guided with its original surface from the outer skin of the bow. At its front edge, the plaice supports itself against the unbroken ice. The supporting force, which acts obliquely from below against the unbroken ice, is opposed in its direction of action with a component of the force which is intended to crush the ice in front of the ship into the ship-wide floe described at the beginning; it therefore has a refractive power-reducing effect. At the same time, the ship must apply the longitudinal component of this force through increased propeller thrust. Since the longitudinal component of the refractive power also has to be applied by the thrust of the propeller, the support of the broken floe and all the floes behind it affects twice in the propeller thrust, whereby all floes "sticking" under the ship floor work together twice, and first because of the frictional force component opposite to the thrust and secondly because of the frictional force component opposite to the breaking force. The first frictional force component thus promotes a higher propeller thrust even if the friction was absorbed in a different environment than the ice lying in front. The second component extinguishes part of the breaking force, so that the ship would have to be pushed onto the ice even higher by increasing the thrust than if there were no frictional force.

From DE-A-21 12 334 a ship with an icebreaker bow is known, the hull of which merges into an underwater foredeck with two wedge-shaped icebreaker legs which enclose a channel between them. At the rear end of the gutter is a snow plow-like guide arranged under the ship's floor. The resulting many small ice floes cannot be slid under the fixed ice sheet on the side, but float into the space between the hull and the fixed ice sheet on the side and cause increased friction on the ship's outer skin, or they collect in the channel and slide underneath the ship the ship to the propeller area. Therefore, such a ship has an increased power requirement and the propellers are exposed to the damaging effects of ice floes.

Furthermore, EP-A-00 79 002 discloses the shape of a foredeck according to the preamble of claim 1, for example for icebreakers. For this purpose, a ship is for a trip in open or ice-covered water with a pontoon-shaped foredeck above the waterline, which has parallel side walls and a frontal surface that extends across the entire width of the ship and in the underwater ship has a flat and strongly inclined forward surface merges towards the rear into a central keel, and is provided with a stern and with drive devices accommodated in it, in such a way that the side edges in the transition region of the fore-end side walls to the end face are curved in the longitudinal direction in the longitudinal direction and protrude laterally from the planes formed by the fore-end side walls are that the distance between the side edges below the construction water line forms the greatest width of the underwater ship, the undersides of the frames between the two side edges from the point of the ski length at which the end face merges with the middle keel, to the point at which it reaches the ship's bottom, transversely downwards are arched or buckled. Due to this design, a ship with a low power requirement for propulsion should be created without great technical, constructive effort and in particular with ice-breaking properties, the conditions for the shear fracture of a one-piece floe from the solid ice sheet being made even more favorable and the guidance of the floe under the water with reduced risk of clod crushing is improved to many fragments, so that the lateral placement of the floe under the solid ice sheet is achieved even more reliably.

In all of these ice-breaking ships, the support of the broken ice floe and the ice floe behind it has multiple effects in the propeller thrust. This forward support would not be necessary if there were no frictional forces between the ship's skin and the ice surface of the submerged ice floes. These frictional forces can never be completely prevented, but their size depends crucially on the execution of the contact between the ice surface and the hull. The presence of a lubricating film between the hull and the ice is of crucial importance. Even if no water can penetrate the space between the ship's skin and the ice, if the relative movement between the ship and the ice is sufficiently large, a lubricating film of melted water will automatically form due to the frictional heat. In addition, the thermal state of this area is such that the heat of fusion is greater than the heat dissipated. However, this applies to slow ship movements, ie in the border area the icebreaking ability of the ship and at very low outside temperatures. The only small frictional heat generated at such a low speed is quickly dissipated again by the very cold surrounding ice and the very cold steel of the ship's hull, so that at best dry friction occurs with the consequence of a very high frictional force. When the movement stops, the ice floe can even freeze to the steel of the outer skin, so that the ice floe can only be detached from the ship with increased effort.

WO 83/04232 discloses an ice guiding system for facilitating the passage of a ship through water carrying ice, the ship having a hull and pumping means for drawing water from the sea through an entry into the hull, with a first and a second number Outlet openings, which are formed at a mutual distance in the port and starboard side of the ship's hull under the rear sight of the ship, with a number of jet generators, each with a water inlet, a gas inlet and a gas / water outlet and which are mounted in the ship's hull, each gas / water outlet is directly associated with an outlet opening, and which have a pipe section with a constriction downstream of a converging section, and with lines for coupling the outlet of the pumping means to the water inlet in order to produce a gas / water mixture with each jet generator and through the jewe output assigned to ils. This ice guiding system is designed so that each jet generator is a jet pump, the suction chamber of which is at least partially is formed by the converging section and which has a nozzle arrangement with a converging nozzle, which is mounted largely concentrically in the pipe section and emits a water flow in it near the converging section, and that the nozzle arrangement has a vortex generator upstream of the converging nozzle and one not has pressurized gas source connected to each of the gas inlets.

In this ice guiding system, the principle of the known water jet pump is used, in which the water pressed or flowing through the pump body entrains a gaseous medium, here air. In addition, the jet nozzle of this ice guiding system is provided with a vortex generating device which is designed as a vortex generator. This ice skating system does not heat up the outer skin. The water pressed through the outlet openings in the ship's outer skin simply keeps broken and floating ice floes away from the ship's outer skin, so that the frictional resistance between ice floes or ice cover is reduced.

According to US-A-4,029,035, a combined arrangement of outer skin heating from the inside and exhaust gas heating from the outside by blowing out compressed combustion gases is known. A separate heating device is provided for this heating. The existing exhaust gases from the ship's engine are not used to heat the outer skin of the ship's hull. Such heating devices represent additional devices for which a separate energy supply is required. Such additional heaters are uneconomical. In addition, there is only heating of the outer skin and no heating of the end face of a pontoon-shaped foredeck in an icebreaking ship.

The invention has for its object to reduce the icebreaking resistance in an ice-breaking ship by reducing the adhesive and frictional forces acting on the foredeck of ice and ice provided with a blanket of snow, in particular the forces of static friction when the ship comes to a halt in ice obstacles.

This object is achieved in an ice-breaking ship according to the type described above by the features specified in claim 1.

In the outer skin zones of the hull, in which increased friction or adhesive forces occur, outlet openings are provided through which a mixture of external water and hot exhaust gases from the machine systems is expelled. While in conventional ice nozzle systems, air is sucked in by driving water in the nozzles acting as ejectors, so that an air / water mixture is formed at the ejector outlet, an exhaust gas / water mixture is used according to the solution according to the invention, the exhaust gas from the machine system, ie the Main ship's engine is removed. The exhaust gas of the ship's main propulsion engine required for the mixture is taken from the exhaust pipe leading to the chimney between it and the muffler. The exhaust gas is fed to the nozzles via a blower and since the nozzles can act as ejectors during operation the blower pressure should be kept low. The exhaust gas temperature between the exhaust gas boiler and the muffler in the exhaust pipe coming from the ship's main propulsion engine is over 180 ° C, depending on the type, design and load of the ship's main propulsion engine kW. If the supply of motive water is stopped, the hot exhaust gas that continues to emerge from the nozzle protects the systems against freezing.

The advantage of using an exhaust gas / water mixture is that the nozzle system is independent of the cold outside air. Depending on the amount of exhaust gas, the temperature of the exhaust gas and the amount of propellant water, there is even a slight heating of the partial water in the nozzle. When the motive water fittings are closed, the nozzles and the nozzle outlets are constantly heated by the escaping exhaust gas as protection against freezing. The device for reducing the resistance to ice friction with the nozzles is preferably provided in the inclined end face of the bow, but also an arrangement of the nozzles in the entire outer hull area, i.e. in all critical outer skin zones is possible, the arrangement in the area of the fore ship being preferred in order to contribute to the heating of the outer skin of the end face.

The exhaust gas / water mixture is fed from the interior of the hull to the outer skin zones of the hull, in which there is greater ice friction or adhesive forces. This heating is preferably carried out from the inside by arranging tanks or chambers for water, operating materials or liquid cargo which adjoin the outer skin of the ship's hull, the tank liquids by heating to at least a temperature slightly above the freezing point of the outside water. However, heating from the interior of the hull can also take place by passing hot machine gases along the required outer skin surfaces or by conveying hot operating fluids along the required outer skin surfaces.

Advantageous embodiments of the invention are characterized in the subclaims.

• Fig. 1 in einer schematischen Seitenansicht die Anordnung einer mittels eines Abgas/Treibwassergemisches betriebenen Düse in der Außenhaut der geneigten Stirnfläche eines pontonförmig ausgebildeten Vorschiffs,
• Fig. 2 in einer schematischen Ansicht den Betrieb der Düse mittels Abgas, welches der von der Schiffshauptantriebsmaschine kommenden Abgasleitung entnommen wird, und
• Fig. 3 in einer Seitenansicht das Vorschiff eines eisbrechenden Schiffes mit einer Außenhauterwärmungseinrichtung.

Embodiments of the invention are explained below with reference to the drawings. It shows

• 1 is a schematic side view of the arrangement of a nozzle operated by means of an exhaust gas / propellant mixture in the outer skin of the inclined end face of a pontoon-shaped foredeck,
• Fig. 2 is a schematic view of the operation of the nozzle by means of exhaust gas, which is taken from the exhaust pipe coming from the main engine of the ship, and
• Fig. 3 is a side view of the bow of an icebreaking ship with an outer skin heating device.

1 and 3, a pontoon-shaped foredeck 10 of a hull 100 of an icebreaking ship is designated as an exemplary embodiment. In the foredeck 10, this icebreaking ship has a section that extends over a substantial part of the ship's width, front surface 12 inclined upwards. This end face 12 is delimited at its outer lateral edges by two side edges 14, which are preferably partially curved in the longitudinal direction, of which only one side edge is shown in FIGS. 1 and 3. These side edges 14 can protrude laterally with respect to the overlying hull. The end face 12 of the fore-end 10 can be increasingly arched or bent downward transversely from the front to the rear; In addition to a flat configuration of the front surface 12 of the fore-end 10, which is designed to be strongly inclined forward, this front surface 12 can also be convex or concave. Laterally, the end face 12 of the foredeck 10 merges into side walls 11; only one side wall of these two side walls is shown in FIGS. 1 and 3. The outer skin of the end face 12 of the bow 10 is indicated at 13.

In the area of the outer skin 13 of the hull 100 and / or in the outer skin of the inclined end face 12 of the bow 10, that is to say in the area of the bow, a device 20 is provided for reducing the resistance to ice friction (FIG. 1).

This device 20 for reducing the ice friction resistance consists of a number of outlet openings 21 formed in the outer skin 13 or in the outer skin of the end face 12, through which a mixture of outside water and hot emissions from the machine system 26 is expelled. In the exemplary embodiment shown in FIG. 1, an outlet opening 21 is shown in the outer skin 13 of the end face 12. In the area of this outlet opening 21, a nozzle 22 is arranged, which is designed as an ejector, which is indicated at 23. The propellant water is supplied to the nozzle 22 via 24, while exhaust gas is supplied in the direction of the arrow 25, specifically via provided piping, not shown in the drawing.

The outlet openings are provided in the outer skin wherever critical outer skin zones are to be kept warm in order to reduce the frictional forces caused by snow and ice acting on the outer skin 13 of the hull 100.

The exhaust gas for the nozzles 22 is removed from the exhaust pipe 28, which comes from the ship's main propulsion engine 26 and is guided into the chimney 30. According to FIG. 2, an exhaust gas boiler 27 and a silencer 29 are arranged in the exhaust line 28. The removal of the exhaust gas to the nozzles 22 is preferably carried out between the exhaust gas boiler 27 and the muffler 29 via a line 28a opening into the exhaust gas line 28, which leads to the nozzle 22 or the nozzles 22, a fan 32 being switched on in this line 28a . Exhaust gas is removed from the exhaust line 28 via this fan 32 and fed to the nozzle 22. The supply of the exhaust gas to the nozzle 22 can be regulated via a three-way flap indicated at 33. The exhaust gas is recirculated from the three-way flap via line 28b back into the exhaust line 28, and as can be seen from FIG. 2, between the silencer 29 and the chimney 30.

In most cases, the exhaust gas drawn off from the exhaust pipe 28 has a temperature which is above 180 °. At higher exhaust gas temperatures, it is possible to bring the exhaust gas temperature to the respectively required or desired temperature by means of heat exchangers connected in line 28a.

The arrangement of the nozzles 22 is preferably carried out in the outer skin 13 of the hull, namely in the critical outer zones which are to be kept warm or in the outer skin of the end face 12 of the bow 10, as shown in FIG. The number of nozzles 22 provided will depend in each case on the size of the zone to be kept warm or on the end face 12. However, there is also the possibility of arranging nozzles in further fore-ship areas or in the outer skin of the hull adjoining the fore-ship in the underwater area, by means of which the resistance to ice friction can be reduced, all of these nozzles then also having a mixture of exhaust gas / Driving water operated.

The embodiment shown in FIG. 3 shows a bow 10 for an icebreaking ship with an inclined, preferably flat end surface 12, which can also be designed as a convex or concave surface. The outer skin 13 of the end face 12 of the bow 10 is also provided with a device 120 for reducing the resistance to ice friction, but this device 120 consists of a device 50 heating the inclined end face 12 or the outer skin 13 of this end face 12, so that the end face 12 insofar as this has frictional contact with broken ice, is kept at a temperature above the melting point of the ice by supplying heat. The solid ice cover is indicated in FIG. 3 at 60 and the broken ice floes are designated by 61, with the ice floes 61a, 61b sliding along the outer wall 13 of the end face 12 of the bow 10 of the broken ice floes 61.

The outer skin zones of the hull, in which there is greater ice friction or adhesive forces, can also be heated from the interior of the hull, this heating by arranging tanks or chambers 51 for water, fuels or liquid charge adjacent to the outer skin of the hull, the tank liquids being brought to at least slightly above the freezing point of the outside water by heating, or by passing hot machine gases along the necessary ones Outer skin surfaces are made. The heating can also take place from the interior of the hull by conveying hot operating fluids along the required outer skin surfaces.

An advantageous embodiment of the invention consists of enlarging the surface area of the critical outer skin zones by means of a wave-shaped configuration of the outer skin, and thus increasing the heat input. If the wave profile is arranged appropriately in the direction of the streamlines, slamming phenomena in the sea can be alleviated at the same time.

Furthermore, there is the possibility of providing the end face 12 with a chamber system, not shown in the drawing, by which the heated, i.e. hot exhaust gases or a heated liquid medium is continuously passed through, which emits its heat to the outer skin 13 and this is brought to the desired temperature.

If the icebreaking ship is provided with an approximately pontoon-shaped fore-ship with two side edges which form the greatest width of the underwater ship and which penetrate the water line which is narrowing behind them on the bow of the ship, the side edges can be provided with heating devices for increased heat supply. The heating device is designed to be controllable in such a way that the supply of heat generates a temperature in the side edges which ensures a desired lubricating film of melted water which is adapted to the ice conditions.

If the icebreaking ship is preferably provided with an approximately pontoon-shaped fore section with two side edges which form the greatest width of the underwater ship and which penetrate the water line which is narrowing behind them on the bow of the ship, such a foreship design with outlet openings for an exhaust gas / water mixture enables the overcoming of the problems in the known icebreakers caused by supplying heat. Because the entire outer skin of the ship's inclined front surface, along which broken ice floes are sliding, is heated, it is impossible to remove the frictional heat, so that even when the ship is at a standstill, a water-lubricating film is always retained, which has the double effect mentioned above broken ice floes on the icebreaking resistance. The supply of heat is carried out in such a way that a medium located above the outer skin, primarily ballast water or fuel, is kept at a constant temperature a few degrees above the melting point of the ice by means of heating devices.

Preferably, the water lubrication film thickness is optimally adapted to the respective icebreaking conditions, i.e. the temperature of the heating device can be adapted to the required lubricating film thickness. The water emerging from the outlet openings in the ship's bottom can be diverted and can be discharged transversely to the longitudinal axis of the ship without the addition of air or gas on the sides above the side edges.

In order to achieve an optimal effect with the smallest possible heat requirement, the end face 12 can have a corrugated profile or another suitable profile be provided, the indentations and elevations of the wave profile extending in the longitudinal direction of the hull. This increases the surface area of the outer skin and optimizes the heating of the outer skin.

The outer skin 13 of the end face 12 of the fore ship 10 is preferably heated in that area of the outer skin in which the broken ice floes 61a, 61b slide along, but heating of the entire outer skin of the hull in the underwater area is also possible.

Claims (4)

1. Icebreaking ship with a pontoon-like foreship (10) lying above the waterline, which has sidewalls that proceed parallelly to each other and, extending across the entire width of the ship in the underwater hull, a plane frontal area (12) strongly inclined toward the front, or, from the front to the rear, constructed athwartships so as to be increasingly downwardly curved or downwardly bent, in which the lateral edges (14) form the greatest width of the underwater hull, which, on the ship's bow, penetrate waterlines that become narrower behind them, characterized in that, in order to reduce the forces of adhesion and the frictional forces acting upon the skin (13) of the inclined frontal area (12) of the foreship (10) produced by ice and by ice with a snow cover, more particularly the latent frictional forces when the ship is caught in ice obstacles, the waste gases of the waste gas-generating heat sources in the hull are supplied to the skin (13) or to the critical skin zones for the production of a film of liquid or a lubricating film on the ship's skin, the waste gases of the ship's main propelling engine (26) between the latter and the muffler (29) of the waste gas main (28) leading to the stack (30) being collected and supplied either unmixed or mixed with sea water to the skin (13) at such a temperature that the skin is maintained at a constant temperature which lies a few degrees above the melting point of the ice, and in which, in the skin (13), discharge orifices (21) for the waste gases or the waste gas and sea water mixture are provided.
2. Icebreaking ship according to Claim 1, characterized in that critical skin zones of the hull (100) are heated from the interior of the hull.
3. Icebreaking ship according to Claim 2, characterized in that the heating from the interior of the hull is effected by hot engine gases being conducted along the critical skin zones.
4. Icebreaking ship according to any of Claims 1 to 3, characterized in that, within the area of the waterlines in the foreship (10) of the hull (100), a wave-like profile is disposed, whose wave troughs proceed in the streamline direction.

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