EP4361019A1 - Device for creating an air shut-off surface on a ship's hull - Google Patents

Abstract

The invention relates to a device for producing an air barrier surface on a ship's hull (1) on which at least one propeller (2) is arranged.The object of the invention is to propose a device for producing an air barrier surface on a ship's hull in the area of the propeller, which is simple in construction and reliable to operate.This object is achieved in that the device comprises a slot-shaped outlet opening (8) and a supply channel (6) through which water is supplied to the outlet opening (8) at an overpressure, which water exits from the slot-shaped outlet opening (8) as a water curtain (9).

Description

Technical area

The invention relates to a device for generating an air barrier surface on a ship's hull on which at least one propeller is arranged.

State of the art

The propeller, also called a ship's screw, is used to drive the ship and is located below the ship's hull. It has several blades that are attached to a hub and rotate around the axis of the propeller. The axis of the propeller is usually aligned in the longitudinal direction of the ship's hull during normal operation and the blades of the propeller graze over a circle that lies in a plane transverse to the longitudinal direction of the ship's hull when rotating. This circle is called the propeller circle area. However, there are also designs in which the propeller circle area is mounted on the ship's hull at a small angle to the longitudinal direction. There are also variants in which the propeller circle area is oriented parallel to the direction of travel. This variant is used in transverse thruster systems and generates a thrust in the transverse direction that is required for maneuvers in the harbor. Rudder propellers are also known that are attached to gondolas that can be rotated through 360° and can therefore be rotated to the longitudinal direction of the ship's hull. The propeller pumps the water beneath the ship's hull from a suction side, where the water is sucked in in front of the propeller and which is located in front of the propeller's circular area, to a pressure side behind the propeller. The terms "in front of" and "behind" refer to the propulsive force generated by the propeller, i.e. the vector of the propulsive force points forward and the water is pumped backwards by the propeller.

When using propellers, particularly on inland vessels, it is known that when the load is low, the tips of the propeller blades in the upper area of the circular area of the propeller are close to the water surface or even break through it, causing the propeller to surface. The rotating propeller accelerates the water and causes the water level on the suction side in front of the propeller to drop. As a result, air can be sucked in through the propeller. This phenomenon occurs particularly when starting off, when high thrust is required and the speed of the vessel is low.

Because air is approximately 800 times denser, the intake of air and the submersion of the propeller usually leads to a massive drop in propeller thrust and thus to a significant loss of ship propulsion. As a result, ships with partially submerged propellers often cannot get off the ground easily. This is especially true if the propeller is designed for fully submerged operation.

To prevent air from entering, ships that operate in shallow waters with little draft, for example, are equipped with a so-called tunnel. For this purpose, part of the outer skin of the ship's hull is extended below the water surface as a skirt. The skirt forms an air barrier. The working propeller, also called a propulsor, accelerates the water flowing to the propeller and sucks the tunnel full of water. A ship's hull with such a tunnel is known, for example, from the publication CN 104 760 678 A Because of the tunnel, the propeller is exposed to water over the entire propeller area and generates thrust. However, once the tunnel is above the water, ventilation, ie air can enter the area of the propeller, can take place via the back of the tunnel. This is designed to be open in order to minimize resistance during fully submerged operation.

The disadvantage of a tunnel on the ship's hull is that the skirt creates additional flow resistance when fully submerged. To avoid this, the publications EP 1 300 330 A1 and EP 3 118 102 A1 Devices for forming a tunnel on the ship's hull are provided. Receptacles are formed on the ship's hull in which panels or wall elements can be arranged, which can be extended downwards and, if necessary, sideways to form the tunnel. Such a device is complex to construct. It can be expensive and prone to errors.

Summary of the invention

The object of the invention is to propose a device for generating an air barrier surface on a ship's hull in the area of the propeller, which is simple in construction and reliable to operate.

This object is achieved in that the device comprises a slot-shaped outlet opening and a supply channel through which water is supplied to the outlet opening at an overpressure, which water exits the slot-shaped outlet opening as a water curtain, wherein the water curtain extends over the entire distance over which the inflow of air to the propeller can take place.

In other words, a kind of slot nozzle is installed near the propeller and preferably on the ship's hull, from which a water curtain emerges when the water supply is activated, forming the air shut-off surface. The water emerging from the slot-shaped outlet opening is pressurized and therefore emerges from the outlet opening at an increased speed. The water has a much higher density than air and prevents air from flowing to the propeller at least up to a certain depth of the propeller. In principle, it is known to use a water curtain to prevent undesirable air currents. In the WO 2003/ 070 557 A1 For example, it is proposed to use a water curtain to prevent the air from escaping from an air cushion that supports a boat. Conversely, there is no known proposal to use a water curtain to prevent an undesirable flow of air to a ship's propulsion system.

• sie erstreckt sich im hinteren Bereich des Schiffsrumpfs quer zur Längsachse des Schiffsrumpfs;
• sie erstreckt sich seitlich des Propellers im Wesentlichen parallel zur Längsachse des Schiffsrumpfs;
• sie erstreckt sich entlang einer gebogenen oder abgewinkelten Linie des Schiffsrumpfs;
• sie erstreckt sich entlang mindestens eines Abschnitts einer Ummantelung des Propellers unterhalb des Schiffsrumpfs.

In practice, the slot-shaped outlet opening can have at least one of the following features:

• it extends in the rear area of the ship's hull transversely to the longitudinal axis of the ship's hull;
• it extends laterally from the propeller essentially parallel to the longitudinal axis of the ship's hull;
• it extends along a curved or angled line of the ship's hull;
• it extends along at least a portion of a propeller casing below the ship's hull.

In a first application, the water curtain can be created behind the ship's hull. Particularly with propellers that are arranged in tunnels, there is a risk that air will be sucked along the underside of the ship's hull from the rear to the suction side of the propeller at the front if the displacement is large. A water curtain along the rear end of the ship's hull counteracts such an air flow. Such a water curtain is created by a slot-shaped outlet opening that extends behind the propeller on the underside of the ship's hull in its rear area, transverse to the longitudinal axis of the ship's hull.

The water curtain can also form the lateral air barrier surface and thus act as an air barrier surface of a tunnel running in the longitudinal direction of the ship. In this case, it prevents the lateral inflow of air. To achieve this, the slot-shaped outlet opening extends to the side of the propeller on the underside of the ship's hull in the Substantially parallel to its longitudinal axis. If the vessel has a central propeller, two outlet openings may be located laterally along the centre of the hull and laterally along the propeller circular area, which form the two side walls of a tunnel. If the vessel has one or two screws outside the centre of the hull, the hull often slopes downwards along the side of the propeller closest to the centre of the vessel. There is therefore no risk of air ingress on this side. In this case, the device may have only one slot-shaped outlet opening for each propeller, located laterally along the propeller circular area from the centre line of the hull and forming the transverse outer wall of the tunnel. The roof of the tunnel and the transverse inner wall of the tunnel are formed by the hull itself.

The air shut-off surface can also extend along a curved or angled line. It can initially run close to the side edge of the ship's hull on its underside essentially parallel to the longitudinal axis of the ship's hull and then in the stern area of the ship's hull perpendicular to its longitudinal axis. In this case, it blocks both the entry of air from the side and the entry of air from the rear. If a slot-shaped outlet opening initially extends along the left side of the ship's hull to the stern and then along the right side of the ship's hull to the front, it prevents air from entering from both sides and from the stern to the propeller circular area.

In the case of a rudder propeller, the slot-shaped outlet opening can also run along a ring that surrounds the nacelle of the rudder propeller. This ensures that no air flows to the propeller from any side, regardless of the angle to which the nacelle below the ship's hull that carries the propeller is rotated.

Finally, the slot-shaped outlet opening can also be arranged along at least one section of a casing of the propeller below the ship's hull. In this configuration, it can create a curtain of water radiating upwards and/or downwards from the propeller casing, which prevents the inflow of air.

The different variants of an air barrier surface, which are formed by the water curtain emerging from the slot-shaped outlet opening, are explained below with reference to the attached drawings. Of course, several slot-shaped outlet openings can also be combined in one device in order to prevent the air flow to the propeller or to several propellers arranged on the ship's hull.

In practice, the device can have a pump which pumps the water to the at least one slot-shaped outlet opening. The water can be sucked in from the water surrounding the ship by means of the pump through at least one inlet opening in the ship's hull. However, it is also possible to arrange the inlet opening in the screw jet in which the water is accelerated by the ship's propeller without using a pump to generate excess pressure. This embodiment is explained in the drawing description. The inlet opening can be provided with a cover which prevents water from flowing in during normal operation.

In practice, the slot-shaped outlet opening can have a covering means. The slot-shaped outlet opening can be closed with the covering means when no water curtain is required to form a tunnel. In this way, a negative influence on the flow around the ship by the slot-shaped outlet opening during normal operation is avoided when the formation of a tunnel is not required.

In practice, the slot-shaped outlet opening can be arranged in a water guide pipe. The water guide pipe forms the supply channel through which the water flows to the slot-shaped outlet opening. The water guide pipe is connected to the inlet opening via the pump, so that the pump supplies water to the water guide pipe at increased pressure.

In practice, the slot-shaped outlet opening can be directed downwards so that a curtain of water falls out of it. The effect of gravity therefore accelerates the water in the water curtain and increases the momentum of the water in the water curtain. Due to the increased momentum of the water, the water curtain can withstand an increased pressure difference compared to the ambient pressure without air flowing to the propeller. It can also be useful to direct the slot-shaped outlet opening and the water curtain it creates slightly outwards. This means that the water does not flow vertically downwards but outwards at a slight angle away from the propeller. The water curtain is sucked towards the propeller due to the negative pressure on the suction side of the propeller. A water curtain directed outwards at an angle counteracts a higher pressure difference than a water curtain emitted vertically downwards.

However, it can also be useful to radiate the water curtain upwards. This is the case, for example, if the slot-shaped outlet opening is on a casing for a propeller is arranged below the ship's hull and the water is jetted upwards against the ship's hull from the slot-shaped outlet opening.

In practice, a cover pipe can be arranged in the water guide pipe, which has a slot and can be rotated in relation to the water guide pipe. In a first rotational position, the slot in the cover pipe is in line with the slot-shaped outlet opening of the water guide pipe and exposes the slot-shaped outlet opening for the water curtain to exit. In a second rotational position, the slot in the cover pipe is rotated relative to the slot-shaped outlet opening so that the cover pipe covers the slot-shaped outlet opening. However, other covering means for the slot-shaped outlet opening can also be used, especially if the slot-shaped outlet opening is curved. For example, cover slides or cover flaps can be used to cover the slot-shaped outlet opening.

The best way to create an air barrier is to manufacture it when a new ship is being built. However, it is also possible to subsequently install the slot-shaped outlet opening on a ship that is already in operation in order to protect it against air being sucked in by the ship's propeller.

Short description of the drawings

• Fig. 1 zeigt eine schematische dreidimensionale Heckansicht eines links der Mitte liegenden Abschnitts eines Schiffsrumpfs, welche die Druckverhältnisse verdeutlicht.
• Fig. 2 zeigt eine der Figur 1 entsprechende Ansicht eines Schiffsrumpfes mit Tunnel.
• Fig. 3 zeigt eine schematische dreidimensionale Darstellung einer erfindungsgemäßen Vorrichtung.
• Fig. 4 zeigt eine der Figur 3 entsprechende Darstellung einer anderen Ausführungsform der Vorrichtung.
• Fig. 5 zeigt eine schematische Seitenansicht des unteren Heckbereichs eines Schiffsrumpfs mit Schiffsschraube mit der hier beschriebenen Vorrichtung.
• Fig. 6 zeigt eine der Figur 1 entsprechende Ansicht des linken Heckbereichs eines Schiffsrumpfs mit der hier beschriebenen Vorrichtung.
• Fig. 7 zeigt eine schematische dreidimensionale Heckansicht eines Schiffsrumpfs mit der hier beschriebenen Vorrichtung, an dem zwei Ummantelungen für Schiffspropeller vorgesehen sind.
• Fig. 8 zeigt eine der Fig. 7 entsprechende Ansicht eines Schiffsrumpfs mit einer Propellerummantelung.
• Fig. 9 zeigt eine Seitenansicht eines Propellers eines Bugstrahlruders mit der hier beschriebenen Vorrichtung.
• Fig. 10 zeigt eine dreidimensionale Heckansicht schräg von unten eines Ruderpropellers mit einer Austrittsöffnung gemäß der hier beschriebenen Vorrichtung,
• Fig. 11 zeigt eine an einem Schiffsrumpf angebrachte Ummantelung eines Schiffspropellers mit einer hier beschriebenen Vorrichtung in Heckansicht.
• Fig. 12 zeigt die Ummantelung aus Fig. 11 mit darin angeordnetem Schiffspropeller in dreidimensionaler Ansicht schräg von unten ohne den Schiffsrumpf.
• Fig. 13 zeigt einen schematischen Längsschnitt durch einen Schiffsrumpf mit einer hier beschriebenen Vorrichtung.
• Fig. 14 zeigt einen der Fig. 13 entsprechenden Längsschnitt durch einen Schiffsrumpf mit einer alternativ angeordneten Eintrittsöffnung.
• Fig. 15 zeigt ein Ruder mit der Eintrittsöffnung aus Fig. 14 in dreidimensionaler Darstellung.

Practical embodiments and advantages of the invention are described below in conjunction with the drawings.

• Fig.1 shows a schematic three-dimensional stern view of a left of center section of a ship's hull, which illustrates the pressure conditions.
• Fig.2 shows one of the Figure 1 corresponding view of a ship's hull with tunnel.
• Fig.3 shows a schematic three-dimensional representation of a device according to the invention.
• Fig.4 shows one of the Figure 3 corresponding representation of another embodiment of the device.
• Fig.5 shows a schematic side view of the lower stern area of a ship's hull with a propeller with the device described here.
• Fig.6 shows one of the Figure 1 corresponding view of the left stern area of a ship's hull with the device described here.
• Fig.7 shows a schematic three-dimensional stern view of a ship's hull with the device described here, on which two casings for ship propellers are provided.
• Fig.8 shows one of the Fig.7 corresponding view of a ship's hull with a propeller shroud.
• Fig.9 shows a side view of a propeller of a bow thruster with the device described here.
• Fig.10 shows a three-dimensional rear view obliquely from below of a rudder propeller with an outlet opening according to the device described here,
• Fig. 11 shows a casing of a ship's propeller attached to a ship's hull with a device described here in a stern view.
• Fig. 12 shows the casing made of Fig. 11 with ship's propeller arranged inside in a three-dimensional view obliquely from below without the ship's hull.
• Fig. 13 shows a schematic longitudinal section through a ship's hull with a device described here.
• Fig. 14 shows one of the Fig. 13 corresponding longitudinal section through a ship's hull with an alternatively arranged inlet opening.
• Fig. 15 shows a rudder with the inlet opening made of Fig. 14 in three-dimensional representation.

Description of the embodiments

The Fig.1 shows schematically the rear left corner of a ship's hull 1 in stern view, ie with a viewing direction corresponding to the direction of travel of the ship. The deepest area of the underside of the ship's hull 1 is in the middle of the ship. It should be noted that the elements of the ship are only sketched very schematically in order to clarify the functioning of the device described here. The area shown shows only the right half of the stern area of the ship's hull 1. The ship's hull is not shown in its full height and length. A propeller 2 is arranged to the left of the center of the ship's hull 1. The Fig.1 shows a state with a low load on the ship's hull 1. In this state, the blade tips of the propeller 2 emerge from the water in the upper area of the propeller's circular area 3. The course of the water surface 4 on which the ship floats is shown schematically in all figures by a line and identified by the reference number 4.

The Fig.1 shows the back of the hull 1 and the propeller circle 3. The suction side of the propeller 2 is on the opposite side. The curved arrows in Fig.1 show the air flow towards the suction side of the propeller, which leads to the propeller blades in the upper area of the propeller circular area 3 being exposed to air and not generating any significant thrust.

The Fig.2 shows one of the Fig.1 corresponding embodiment of a ship's hull 1, which has a longitudinal wall 5 of a tunnel on the side. The wall 5 prevents air from flowing in from the side to the suction side of the propeller 2. But even with this construction it is clear that air can flow along the curved arrows along the underside of the ship's hull 1 to the suction side of the propeller 2, which corresponds to the Fig.2 visible side of propeller 2.

Fig.3 shows a schematic representation of a device according to the present description. A section of a water guide pipe 6 is shown. Water is conveyed into the water guide pipe 6 along an inflow direction 7 shown by a large arrow. The water guide pipe 6 has a slot-shaped outlet opening 8 on its underside. The water guide pipe thus forms the supply channel through which water flows to the slot-shaped outlet opening 8. A water curtain 9 emerges from the slot-shaped outlet opening 8 along the arrows pointing vertically downwards. The rectangular area below the water curtain 9 essentially shows the cross-section of the section of the water curtain 9 that is created below the drawn section of the slot-shaped outlet opening 8. In practice, the water curtain extends over the entire distance over which the flow of air to the propeller can take place.

Fig.4 shows one of the Fig.3 corresponding representation of the water guide pipe 6, which is however shown pivoted so that the center line of the water curtain 9 exiting through the slot-shaped outlet opening 8 forms an angle α to the vertical direction The water curtain is preferably pivoted outwards in relation to the vertical direction, ie away from the propeller, so that the water curtain 9 can prevent the ingress of air even in the case of larger pressure differences.

The Fig.5 shows a schematic side view of a ship's hull 1 with a device arranged therein for creating an air barrier surface. The water guide pipe 6 is attached to the underside of the stern of the ship's hull 1. The slot-shaped outlet opening 8 extends vertically downwards and creates a vertically downward-directed water curtain 9. The long and vertically downward-directed arrow shows the direction in which the water exits from the outlet opening 8. The water curtain 9 forms a barrier against the ingress of air, which without this barrier would flow in the direction of the short horizontal arrows to the Fig.5 left side of the propeller 2. The amount of water supplied to the water guide pipe 6 is to be such that the water curtain 9 forms a sufficient flow resistance for the inflow of air. In this way, it is prevented that air from the stern of the ship to the Fig.5 suction side of the propeller 2 located to the left of the propeller 2. In Fig.5 Furthermore, a flap 15 is shown schematically, which forms a covering means. As in Fig.5 As shown, this flap 15 is opened during the creation of the water curtain 9, ie it protrudes downwards from the wall of the ship's hull 1, which here runs almost horizontally, and exposes the slot-shaped outlet opening 8. If no water curtain is required, the flap 8 is folded upwards so that it runs parallel to the wall of the ship's hull 1 and covers the slot-shaped outlet opening 8.

However, the covering means for the slot-shaped outlet opening 8 can be formed in any other way, for example by a slider which can be pushed over the slot-shaped outlet opening 8 or a second pipe within the water guide pipe which has a slot corresponding to the slot-shaped outlet opening 8, wherein the second pipe is rotatable with respect to the water guide pipe.

In Fig.6 it can be seen that not only the first water guide pipe 6 is provided at the stern of the ship's hull 1, but also a second water guide pipe 6`. The first water guide pipe 6 creates a first water curtain 9 which runs essentially parallel to the stern of the ship behind the propeller circular area 3. The second water guide pipe 6' extends essentially in the longitudinal direction of the ship's hull 1 and creates a water curtain 9` running longitudinally on the side of the ship's hull 1. The lateral water curtain 9' prevents the lateral inflow of air to the suction side of the propeller 2. The water curtains are indicated by the downward-pointing arrows and hand-drawn irregular lines. As in Fig.6 As can be seen, the water guide pipes 6, 6' are arranged depending on the design of the ship's hull and the propeller 2 in such a way that the emerging propeller 2 is completely enclosed by the water surface 4, the walls of the ship's hull, possibly with a tunnel, and the air barrier area formed by the water curtain 9, 9'. As mentioned above, care must be taken to ensure that the water curtain extends over the entire distance over which the flow of air to the emerging propeller 2 can take place.

The Fig.7 shows a variant of a ship's hull 1, in the stern area of which two casings 10 for propellers (not shown) are arranged. Two walls 5 and 5' form a tunnel on each side of the ship. A transverse water guide pipe 6 extends along the stern on the underside of the ship's hull 1 in the transverse direction of the ship's hull 1 and forms a transverse water curtain 9 behind the casings 10 for the propellers (not shown). In Fig.7 Furthermore, a supply line 11 for the supply of water to form the water curtain 9 in the area of the middle of the stern of the ship's hull 1 can be seen. The water curtain 9 is also represented here by a large number of hand-drawn uneven lines.

Fig.8 shows schematically a modified embodiment of the ship’s hull 1 from Fig.7 , to which only a casing 10 for a propeller (not shown) is attached. Here too, two side walls 5, 5' are provided to form a tunnel. A water guide pipe 6 running transversely in the area of the stern of the ship's hull 1 forms a downwardly emerging water curtain 9 on the underside of the ship's hull 1, which prevents the flow of air to the suction side of the propeller.

The Fig.9 shows very schematically the front section of a ship's hull 1 with an integrated propeller 12 of a bow thruster. Here, in the bow area of the ship's hull 1, a tunnel 26 is arranged in which the propeller 12 of the bow thruster is arranged. Above the tunnel 26 of the propeller 12 there is a water guide pipe 6", which has a curved course. The slot-shaped outlet opening 8 is located at the Fig.9 invisible underside of the water guide pipe 6" and creates a water curtain 9" around the propeller 12 of the bow thruster, which prevents the inflow of air to the upper area of the propeller circle of the propeller 12. The water curtain 9" in Fig.9 is represented by unevenly curved freehand lines.

The Fig.10 shows a rudder propeller 13 which is arranged within a rotating nacelle 14. The rotating nacelle 14 can be rotated about a vertical axis and is below the The rotating nacelle 14 is designed as a casing for the rudder propeller, which is rotatably attached to the ship's hull and is connected to the propeller drive in the ship's hull. By rotating the rotating nacelle 14 on the underside of the ship's hull, the rudder propeller 13 can be aligned as desired in relation to the longitudinal direction of the ship.

Furthermore, Fig.10 schematically a slot-shaped outlet opening 8' can be seen, which is designed as a circular slot on the underside of the ship's hull (not shown). In this embodiment, the water guide pipe is located above the lower hull wall in which the slot-shaped outlet opening 8' is mounted and is therefore not in the Fig.10 can be seen. A circular water curtain 9‴ emerges from the ring-shaped, slot-shaped outlet opening 8'. This water curtain 9‴ has the shape of a short cylinder below the circular outlet opening 8', which surrounds the rudder propeller 13. Irrespective of the direction of rotation of the nacelle 14 of the rudder propeller 13, the flow of air from the outside to its suction side is thus prevented.

The Fig. 11 and 12 show an alternative embodiment of a rigid shrouded propeller 2. The propeller 2 itself is only in Fig. 12 shown. In Fig. 11 . the lower section of the stern area of the ship's hull 1 is shown with the two side skirts which form the side walls 5, 5' of a tunnel for the propeller. In this embodiment, the water guide pipe 16 is arranged on the circumference of the casing 10' in the upper area of the propeller 2. The water guide pipe 16 extends over an angular range which is less than half the circumference of a circle, i.e. less than 180°. The water guide pipe 16 has a protuberance 17 on the inside facing the axis of rotation of the propeller 2, which forms the slot-shaped outlet opening 18. The water curtain 19 consequently extends from the water guide pipe 16 into the interior of the casing 10'. The water curtain 19 is again shown by irregular freehand lines. The direction of the water jet from the slot-shaped outlet opening 18 is indicated by arrows extending radially inwards in Fig. 11 shown.

In addition, the water guide pipe 16 has outwardly projecting protuberances 17' in the outer areas, which are located to the side of the axis of rotation of the propeller 2 and thus to the side of the vertical center line of the casing 10. Each of these outer protuberances 17' radiates a water curtain 19' radially outward. In the middle area, ie in the area of the vertical center line of the casing 10' in Fig. 11 , no water curtain is required, since the fastening box 20 for the casing 10' prevents the inflow of air to the suction side of the propeller 2. However, it is also possible to install a water curtain in this middle, upper area of the Water guide pipe 16, the slot-shaped outlet opening 18' is to be formed continuously, so that a water curtain 19' emerges from the water guide pipe 16 continuously from one end to the other and also radially outwards.

In the Fig.10 and 11 the water guide pipe 16 is attached to a rigid casing 10'. However, it is entirely possible to provide a corresponding water guide pipe 16 in a nacelle of a rudder propeller that is mounted so that it can rotate. The water supply for the water guide pipe 16 is provided in the fastening for the casing of the propeller 2.

The Fig. 13 shows a schematic side sectional view of a ship's hull 1 with a device for forming an air barrier surface. An inlet opening 21 is arranged in the ship's hull 1, through which water can be sucked in. A pipe 22 leads from the inlet opening 21 to a pump 23, which guides the water through a further pipe 24 to the water guide pipe 6, from whose outlet opening 8 the water curtain 9 emerges.

A slider 25 is arranged in the area of the inlet opening 21. The slider 25 can be moved to the right from the position shown above the wall of the ship's hull 1 so that it forms a cover for the inlet opening 21. After the start-up process has ended and during normal driving operation, the cover 25 is pushed over the inlet opening 21 and covers it completely. It should be noted that flaps or other locking mechanisms can also be used to close the inlet opening and the slot-shaped outlet openings.

The Fig. 14 and 15 show an alternative embodiment of the inlet opening 21'. The inlet opening 21' is arranged here on a rudder 27, which is located behind the propeller 2. The inlet opening 21' is arranged in the accelerated water flow that is generated by the blades of the propeller 2. This accelerated water flow is also called a screw jet or screw stream. Since the water is accelerated by the propeller 2 in relation to the inlet opening 21', it has increased dynamic pressure and thus an increased total pressure. In this embodiment, a pump can be dispensed with. The pressure increase generated by the propeller ensures the increased pressure in the water guide pipe 6 and generates the water curtain 9.

All drawings contain only schematic sketches of sections of a ship's hull near the propeller, or of the device described here, which Clarify the function of the device described here for creating an air barrier surface.

The features of the invention disclosed in the present description, in the drawings and in the claims can be essential for the realization of the invention in its various embodiments both individually and in any combination. The invention is not limited to the embodiments described. It can be varied within the scope of the claims and taking into account the knowledge of the competent person skilled in the art.

List of reference symbols

1

Hull

2

propeller

3

Propeller circle area

4

Water surface

5, 5'

Wall of a tunnel

6, 6', 6", 6‴

Water pipe, supply channel

7

Inflow direction

8, 8', 8"

slot-shaped outlet opening

9, 9', 9" 9,‴

Water curtain

10,10'

Sheathing

11

Supply line

12

Ducted propeller, propeller

13

Rudder propeller

14

gondola

15

Flap, covering agent

16

Water pipe, supply channel

17, 17'

protuberance

18,18'

slot-shaped outlet opening

19,19'

Water curtain

20

Mounting box

21,21'

Entrance opening

22

Pipe

23

pump

24

Pipe

25

Cover, slider

26

tunnel

27

Rudder

Claims (10)

Device for producing an air barrier surface on a ship's hull (1) on which at least one propeller (2, 12, 13) is arranged, characterized in that the device comprises a slot-shaped outlet opening (8, 8', 8", 18, 18') and a supply channel (6, 6', 6", 6‴, 16) through which water is supplied to the outlet opening (8, 8', 8", 18, 18') at an overpressure, which water emerges as a water curtain (9, 9', 9"9,'", 19, 19') from the slot-shaped outlet opening (8, 8', 8", 18, 18'), the water curtain (9, 9', 9" 9,‴, 19, 19') extending over the entire distance over which the inflow of air to the propeller (2, 13) takes place. can. Device according to claim 1, characterized in that the slot-shaped outlet opening (8, 8', 8", 18, 18') has at least one of the following features: it extends in the rear area of the ship's hull (1) transversely to the longitudinal axis of the ship's hull (1); it extends laterally of the propeller (2, 13) substantially parallel to the longitudinal axis of the ship's hull (1); it extends along a curved or angled line; it extends along at least a portion of a casing of the propeller (2, 13) below the ship's hull (1). Device according to claim 1 or 2, characterized in that it comprises a pump (23) which pumps the water to the slot-shaped outlet opening (8). Device according to one of the preceding claims, characterized in that it has at least one inlet opening (21, 21') through which water from the surroundings of the ship's hull (1) enters and flows to the outlet opening (8). Device according to one of the preceding claims, characterized in that it has a cover (25) for closing the inlet opening (21). Device according to claim 5, characterized in that the inlet opening (21') is arranged in the water flow accelerated by the propeller (2). Device according to one of the preceding claims, characterized in that it comprises a covering means (15) for closing the slot-shaped outlet opening (8). Device according to one of the preceding claims, characterized in that it has a water guide pipe (6, 6', 6", 6‴, 16) in which the slot-shaped outlet opening (8, 8', 8", 18, 18') is arranged. Device according to claims 7 and 8, characterized in that a cover pipe is arranged in the water guide pipe, which has a slot and is rotatable with respect to the water guide pipe. Ship with a hull (1) and a propeller (2, 12, 13), characterized by a device according to one of the preceding claims.

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