GB2244458A - A submarine - Google Patents

Abstract

A discontinuity in the shape of a submarine, caused by provision of a walkway, is provided with a flow control member (1) comprising an outer skin (7) and inner skin (9) forming inflatable sections (3 and 4). The sections (3 and 4) are inflated with water to present a smoothly curved surface masking the discontinuity and enhancing the flow of water as the submarine moves and hence reducing the noise generated by the movement. When the submarine has surfaced, the sections (3 and 4) may be deflated to return the walkway to its angular form. In a second embodiment of the invention the flow of water about a sail or fin of a submarine is modified by an inflatable member to reduce the lateral force generated by the sail.

Description

A SUBMARINE This invention relates to a submarine and a flow control member to enhance the flow of water relative to a submarine travelling through the water.

A known problem with submarines is the drag they experience and the resultant noise created as they pass through the water. Whiist this problem is reduced by designing a submarine to have a smoothly curved shape, it is not always possible to eliminate all discontinuities of shape.

A further problem associated with submarines is the hydrodynamic effect of the fin or sail of the submarine. The fin is the large vertical structure which surrounds a conning tower of the submarine. As the submarine turns, the fin generates a force acting perpendicularly to it.

This lateral force is undesirable because it tends to roll the submarine.

The problem of discontinuity of shape is further compounded by a requirement to provide an accessway which tends to form sharp angular discontinuities in the shape of a submarine.

Accessways can comprise steps but often take the form of walkways about the fin and hull interface.

It is not possible for these to be designed to conform to the general smoothly curved shape of the submarine because such curved surfaces would prove difficult or even dangerous to walk on when wet.

As well as inducing noise by cavitation (called Horseshoe Vortex effects) such sharp angular discontinuities act as radar and sonar reflectors making the presence of the submarine even easier to detect.

According to the invention there is provided a submarine having a fin and a flow control member located in relation to the fin so as to be moveable between a stowed position and a deployed position to modify the flow of water past the fin.

By modifying the flow of water past the fin the hydrodynamic properties of the fin are altered enabling the force produced by the fin in a turn to be reduced or substantially eliminated or where, alternatively, the flow control member bridges a discontinuity between the fin and hull reduces the noise produced by the discontinuity.

Preferably, the or each flow control member has a variable shape to permit the hydrodynamic properties of the fin to be varied. By enabling the flow control members to have a variable shape, different rates of turn may be accommodated.

Preferably, control means is included to determine the required shape for a desired rate of turn, the means conveniently, comprising a computer linked between the helm or auto pilot of the submarine, and a set of valves controlling the deployment.

Preferably, the flow control member is deployed by inflation although for some applications the flow control member may be hinged and deployed by means of hydraulically operated arms.

According to a second aspect of the invention, the flow control member is located in relation to a discontinuity in the external surface of the submarine so as to be moveable between a stowed position in which the discontinuity is exposed to the flow of water and a deployed position in which the control member bridges the discontinuity to modify the flow of water past the discontinuity.

By eliminating the discontinuity of shape, the noise produced by the submarine as it travels through the water is reduced. The discontinuity may be an accessway which may be reinstated when required by moving the flow control member to the stowed position.

The use of the present invention on a submarine means that the turbulence which would be created by the discontinuity as the submarine travels through the fluid is drastically reduced, and hence the cavitation problem is reduced; and the radar and sonar reflective discontinuities in the surface are removed and/or masked.

The use of the present invention improves the flow pattern of the fluid with respect to the discontinuity. In effect this means that the turbulence created by the passage of the submarine through the fluid in the region of the discontinuity is reduced, and therefore the drag coefficient of the submarine is improved as the drag is reduced.

The reduction in the turbulence created by the passage of the submarine means that the large variations in pressure brought about by the vortices created, is reduced if not eliminated, and therefore in water, the cavitation that may result therefrom is eliminated or reduced.

Consequently, the noise created by the passage of the submarine through the water is reduced.

Additionally, where the flow control member is disposed in the flow path to the propulsive means of the submarine, the flow of fluid into the propulsive unit is made less turbulent. This in turn means that the efficiency of the propulsive unit is improved.

Preferably, the flow control member is inflated using the water of the surrounding environment.

In order to achieve this, the flow control member is preferably provided with a sensor or sensors that detect the surrounding environmental pressure and control pump means which inflates the flow control members.

Alternatively, the flow control members are inflated by means of a fluid which is stored in the submarine, for example water, air or gas such as inert gas.

Preferably, a flow control member made in accordance with the present invention is provided with a variable geometry capability. This enables the flow control member to be shaped so as to meet the particular requirements for the environments that will be met. Therefore the flow control member may include symmetric or asymmetric geometry.

In a preferred embodiment of the present invention, the flow control member comprises two inflatable members which co-operate longitudinally along their length to provide the smooth surface transition, i.e. a set of co-operating flow control members.

Although the flow control member provided may comprise a single member, or a singular set of co-operating members it is envisaged, particularly in the situation where the members are readily moveable, that a series of members or sets of cooperating members is provided. This further enhances the variable geometry capability of the flow control member.

Where a series of flow control members are used, they may be interconnected, by means of hydraulic joints and valves.

In a preferred embodiment of the present invention, each of the flow control members comprises an outer skin; a skin member which with the outer skins acts so as to form a bag like member; and a series of diaphragms which are spaced apart in the bag like member and interconnect the outer skin and the skin member.

The diaphragms provide the flow control members with a degree of dimensional stability and prevent the outer skin from adopting an undesired shape profile as a result of the over pressure within the flow control member.

Additionally, the diaphragms may be used to divide the space within the bag like member into a number of pockets to allow variation in shape to be achieved. However, in the preferred embodiment the space within the bag like member will be maintained as a single communicative space.

Alternatively, the outer skin may comprise a series of articulated metallic plates, which may additionally be provided with a layer of polymeric material.

Preferably, in order to prevent the flow control member, or more particularly the discontinuity, acting as a reflective source for sonar signals, the outer skin is manufactured from, or is provided with, a layer of anechoic polymeric material.

Preferably, in order to prevent the flow control member or more particularly the discontinuity, acting as a radar source, the outer skin is provided with an electrically conductive capability.

In the case where the outer skin includes articulated metallic plates, these metal plates provide the electrically conductive capability.

However, in the case where the outer skin is a polymeric material, electrically conductive capability is preferably provided by means of embedded metal wires.

In any event, the outer skin should have sufficient strength to resist damage by foreign, bodies, for example, flotsam or ice.

The flow control member may be incorporated in the submarine during manufacture or according to a further aspect of the invention provided as a retro-fit.

Specific embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 shows a sectional side view of a flow control member made in accordance with the present invention; Figure 2 shows a second sectional side view of the flow control member as shown in Figure 1; Figure 3 shows a schematic representation of the shape of the flow control member under varying flow conditions; Figure 4 shows a sectional side view of a second flow control member made in accordance with the present invention; Figure 5 shows a schematic end view of a submarine in accordance with the invention; Figure 6 shows a schematic plan view of the submarine shown in Figure 5; Figures 7 to 10 show a submarine in accordance with a second aspect of the invention; and Figures 11 to 12 show a second embodiment of the submarine in accordance with the second aspect of the invention.

Referring to Figures 1 and 2 of the accompanying drawings, there is shown a flow control member 1 made in accordance with the present invention which is moveable to enhance the flow of fluid relative to a discontinuity in the surface of a submarine.

The flow control member 1 comprises an upper inflatable section 3; and a lower inflatable section 4 which in the inflated state abut at an interface 2.

Both the upper and the lower inflatable sections are each constructed as an inflatable compartment 5 and 6, comprising an outer skin 7 which is in contact with the surrounding environment when deployed; a skin member 9 which is connected to the submarine wall; and a series of diaphragms 8 which are connected between the outer skin 7 and the skin member 9.

The diaphragms 8 in this example do not act to divide the inflatable compartment 5 or 6 into several individual pockets, they have been provided so as to give the inflatable sections a degree of dimensional stability.

The outer skin 7 of the inflatable compartment in this example, is manufactured from either a polymeric material; or a series of articulated metallic plates which may also be provided with an outer layer of polymeric material.

Further, in order to prevent the flow control member 1 from acting as a reflective source for sonar signals the outer skin 7 is provided with a layer of, or is manufactured from, an anechoic polymer.

Additionally, in order to prevent the flow control member 1 from being a reflective source for a radar signal, the outer skin 7 may also include an electrically conductive means to adsorb the radar signals. In the case where metallic articulated plates are used, these will provide the electrically conductive means. However, where the outer skin 7 is a polymeric material, electrically conductive means, such as wires, are disposed therein.

In any event, the outer skin 7 is manufactured so that the inflatable sections will not sustain damage when impacted by foreign bodies, such as flotsam and ice.

The diaphragms 8 are made from a resistant polymeric material and act to prevent the outer skin 7 from being displaced outwardly to an excessive degree by the pressure within the inflatable compartment when inflated.

In this particular example, the flow control member 1 is shown disposed between the sides of a discontinuity in a surface, which sides are perpendicular to one another. The upper inflatable section 3 is secured to the vertically extending side of the discontinuity, and the lower inflatable section 4 is secured to the horizontally extending side of the discontinuity.

When the lower and upper inflatable sections 3 and 4 are inflated the outer skins 7 co-operate with one another so as to provide a smooth surface transition between the two sides of the discontinuity.

In the inflated state, one side of the outer skin 7 of each inflatable sections 3 and 4 is in contact with the side of the discontinuity to which it is secured whilst the other ends abut at interface 2.

In the inflated state, the diaphragms 8 within the inflatable compartments are disposed as follows.

The upper inflatable section 3 has five substantially horizontal diaphragms which are disposed parallel to one another between the respective outer skin 7 and the respective skin member 9; and the lower inflatable section 4 has eight diaphragms; the four closest to the contact between the respective outer skin 7 and the respective skin member 9 of the discontinuity are disposed vertically parallel to one another and the remaining five are disposed between the outer skin 7 and the skin member 9 at the point of the discontinuity.

In the deflated state, the outer skins 7 of the lower and upper inflatable sections 3 and 4 are disposed substantially parallel to the walls of the discontinuity to which it is secured as shown in Figure 2.

The actual shape which will be induced in the outer skin 7 is dependent upon the forces acting on the outer skin 7, that is to say, the forces exerted by the internal inflation medium of the inflatable sections; the external environment surrounding the inflatable sections; the additionary or subtractory forces induced by the movement of the body through the environment; and the restraining action of the diaphragms 8.

Figure 3 of the drawings shows a schematic plot of several forms of the shape which will be induced in the outer skin 7 of both of the inflatable sections by the above detailed forces. Obviously the actual shape induced is dependent upon the balance of these forces, and will not be constant but vary as the balance of these forces varies.

Now referring to Figure 4 of the drawings, a second form of a flow control member made in accordance with the present invention is shown.

This second form of flow control member is similar to that described with reference to Figures 1 and 2 of the drawings and therefore like numerals refer to like components.

The primary difference between the flow control member shown in Figures 1 and 2 of the drawings and the second form shown in Figure 4 relates to the arrangement of the diaphragms 8 within the inflatable compartments 5 and 6.

Now in the upper inflatable section 3, the diaphragms 8 of which there are five are disposed between the outer skin 7 at points along its length and the skin member 9 at a position on the skin member 9 closest to the actual discontinuity.

Now in the lower inflatable section 4 the diaphragms 8 of which are ten are disposed between the outer skin 7 at points along its length and the skin member 9 at the point of the discontinuity.

Now referring to Figures 5 and 6 of the drawings, a submarine is shown with the flow control member 1 in place. In this example the flow control member 1 is shown in position over a discontinuity, shown in phantom. The discontinuity is the interface between the main body or hull of the submarine and the fin/sail which is angularly shaped in order to form a safe walkway about the fin/sail.

Therefore, the flow control member 1 in this case must be provided with an inflatory and deflatory capability, where the skin 7 of the lower inflatable section 4 in the deflated state provides the surface on which the people actually walk.

The flow control member 1 is inflated and deflated, with sea water, using a pump system (not shown). The actual pressure within the inflatable sections 3 and 4 is directly proportional to the actual pressure of the surrounding environment and therefore the depth of the submarine. The pressure within the inflatable sections 3 and 4 is maintained at a pressure, for example 50psi, slightly in excess of the pressure of the surrounding environment in order to maintain the desired profile, and in particular the smooth transition between the angle of the relevant surfaces.

A further embodiment of the invention is shown in Figure 7, in which a fin 10 of a submarine 11 is fitted with inflatable sections 12 and 13 on either side of the fin 10. The sections 12, 13 are formed in a similar way to the earlier described embodiments that is to say they have an inner and outer skin with transverse shape controlling diaphragms. When inflated, section 12 (and similarly section 13) protrudes from the fin 10 as more clearly shown in Figure 8 to change the cross-section of the fin 10.

As the submarine 11 follows a curved path 14 underwater, as shown in plan view in Figure 10, the fin 10 presents an angle of attack which would result in a lateral force being generated acting in the direction of arrow 15 to roll the submarine 11. However, as the submarine 11 turns the section 12 is inflated with water to vary the hydrodynamic properties of the fin 10 to prevent the lateral force being generated. Section 13 is similarly inflated to prevent a lateral force being generated if the submarine 11 is turned to the left. In both cases, the inflation is controlled by a computer system (not shown) linked to the helm of the submarine 11.

The submarine 11 is also provided with inflatable members 16 about the interface of the hull 17 and the fin 10 to smooth the discontinuity in shape therebetween whilst as in the earlier described embodiments, providing a safe walkway when deflated. The inflatable members vary in section as shown in figures 9a to 9b to present a smoothly changing profile.

In a further embodiment of the invention shown in Figure 11, in which the same reference numerals are used to demote similar structures to those earlier described, the sections 12 and 13 can be inflated to present different profiles. Figure 12 shows the various profiles 18a, b and c that may be adopted by the inflatable sections 12 and 13 to cope with different rates of turn of the submarine 11. Profile 18a is adopted for a relatively low rate of turn whilst 18c is adopted for a maximum rate turn, with 18b being the profile adopted between these extremes. It can also be seen that the section 12 and 13 extend to the hull 17 to provide a smoother change in shape to further reduce noise and drag.

Claims (24)

1. A submarine having a fin and a flow control member located in relation to the fin so as to be moveable between a stowed position and a deployed position to modify the flow of water past the fin.

2. A submarine as claimed in claim 1 in which the flow control member is located at the junction of the fin with the hull of the submarine so as to bridge a discontinuity therebetween when in the deployed position.

3. A submarine as claimed in claim 2 in which the discontinuity is an accessway.

4. A submarine as claimed in claim 2 or 3 in which the flow control member extends around the leading edge of the fin and along both sides extending rearwards therefrom.

5. A submarine as claimed in any one of the preceding claims in which the flow control member is located to one side of the leading edge of the fin and extends alongside said leading edge.

6. A submarine as claimed in claim 5 in which a pair of similar control members are located symmetrically along opposite sides of the leading edge of the fin.

7. A submarine having a flow control member located in relation to a discontinuity in the external surface of the submarine so as to be moveable between a stowed position in which the discontinuity is exposed to the flow of water and a deployed position in which the control member bridges the discontinuity to modify the flow of water past the discontinuity.

8. A submarine as claimed in any one of the preceding claims in which the or each flow control member is separate from and located adjacent to the external surface of the submarine.

9. A submarine as claimed in any one of the preceding claims in which the or each control member comprises a wall of an inflatable structure.

10. A submarine as claimed in claim 7 in which said wall is flexible.

11. A submarine as claimed in any one of the preceding claims in which the shapes of the or each flow control member is variable.

12. A submarine as claimed in any one of the preceding claims including means to inflate the flow control member with water from the surrounding environment.

13. A submarine as claimed in claim 12 including means to match the pressure of the water within the flow control member to that of the environment.

14. A submarine as claimed in any one of the preceding claims in which the or each flow control member comprises an outer skin, a skin member which, with the outer skin, acts so as to form a bag like member and a series of diaphragms which are spaced apart in the bag like member and interconnect the outer skin and the skin member.

15. A submarine as claimed in claim 14 wherein the diaphragms form compartments which are individually inflatable to vary the shape of the bag like member.

16. A submarine as claimed in claim 14 wherein the diaphragms communicate such that the bag like member is maintained as a single communicative space.

17. A submarine as claimed in claims 14, 15 or 16 wherein the outer skin comprises a series of articulated metallic plates.

18. A submarine as claimed in any one of the preceding claims wherein the outer skin is formed, at least in part, from polymeric material.

19. A submarine as claimed in claim 18 wherein the outer skin is formed, at least in part, from anechoic polymeric material.

20. A submarine as claimed in any preceding claim wherein the outer skin is provided with an electrically conductive capability.

21. A submarine as claimed in claim 20 wherein the outer skin incorporates embedded metal wires.

22. A submarine substantially as hereinbefore described with reference to, and as illustrated by, the accompanying drawings.

23. An inflatable flow control member for use on a submarine as claimed in any preceding claim.

24. An inflatable flow control member substantially as hereinbefore described with reference to, and as illustrated by, the accompanying drawings.