WO2024201284A1

WO2024201284A1 - Catamaran hull with variable geometry propuls ive torpedo

Info

Publication number: WO2024201284A1
Application number: PCT/IB2024/052874
Authority: WO
Inventors: Massimo Verme; Roberto Rossi
Original assignee: Verme Projects S.r.l.
Priority date: 2023-03-27
Filing date: 2024-03-26
Publication date: 2024-10-03

Abstract

The present invention is a "hybrid foiling" fairing with variable geometry consisting of a submerged body [ 1 ] with or without wings, retractable and shaped to increase the propulsive ef ficiency at low immersion and connected to a fully emerged platform [ 2 ] by a vertical prop movable according to one or more degrees of freedom [ 3 ]. The system is equipped with two planing side hulls [ 4 ] having a H dual mode H geometry, very thin at flight altitude [V], but much larger when the vessel is stationary [R]. The invention is completed by a system to limit the water flow rate through the manoeuvring propellers placed on the side hulls.

Description

VERME PROJECTS S.R.L.

CATAMARAN HULL WITH VARIABLE GEOMETRY PROPULSIVE

TORPEDO

The present invention applies in the field of fairings for vessels of any size and type of use.

The fairing is of fundamental importance in the design of a vessel or ship.

Its characteristics have an impact both on the economic side and on the environmental impact, as well as in a broad sense on sustainability, also understood as passenger comfort.

In economic terms, the resistance-to-displacement ratio is of primary importance.

With regard to the environmental impact, attention must be paid to the generation of waves, while accelerations, vibrations and setups in navigation, as well as noise, impact on passengers.

Starting from the economic part and analysing the fuel needs per mile travelled, it can be shown that it can be expressed as the product of a factor linked to engine and propulsion, and in particular to specific consumption and total propulsive efficiency, multiplied by the resistance (drag) of the fairing.

The latter force is for most types of fairing proportional to the displacement of the ship, that is, to the weight that the fairing must carry.

The resistance-to-displacement ratio depends on the fairing shape and speed. The fairing form that allows maximum energy savings, if speed limitations are accepted, is the displacing fairing, which also has different qualities in terms of stability and resistance to the sea.

It moves with a very low resistance/displacement ratio, from 1-2% at low speed, until rising and then soaring and exceeding 10-15% after the critical speed: it can simply be approximated with the square root of the floating length, expressed in feet, for 1.34.

Whilst for large ships this speed is very high, over 40 knots for a length of 300 meters.

For small vessels this speed is very low, even below 10 knots. In this case, other types of traditional fairings such as planing ones, with hydrodynamic support, are slightly more convenient from an energy point of view.

In both cases, however, the wave generation is very high and the dynamic behaviour of a small planing vessel offers limited comfort in terms of trim and navigation comfort.

In this scenario, two further types of fairings are included: the "SWATH" fairing and derivatives and the "HYDROFOILS" .

The first minimizes the wave motion and limits the problem of the critical speed of the displacing fairings .

However, it has a lot of wet surface and as speed increases it is not competitive.

Where the operating speed is high, hydrofoils are certainly competitive, managing to limit the resistance/displacement ratio to within 6-7 % in the best cases ; about hal f of a planing fairing .

Where the operating speed is low and the displacement is high, hydrofoils are not the optimal solution ( consider for example a ferry limited to 12- 15 knots that must carry passengers on large lakes or in rivers or canals ) .

The present invention has been des igned to overcome the problems of the prior art , namely to create a fairing that for a certain combination of length and speed i s able to reach speeds higher than the displacing fairing with consumption lower than that of a planing fairing, and at the same time have high standards of comfort and load capacity .

Attempts to achieve these obj ectives with a hybrid-type fairing are known in the art .

An example of these attempts is the fairing equipped with a submerged body and wings , or "HYSWAS" capable o f supporting the entire weight of the vessel at crui sing speed by means of the hydrostatic thrust of the submerged body and that hydrodynamic one of the wings . This type of hybrid fairing has been success fully studied and tested by the US Navy .

A similar version, equipped with s ide hulls that dip at low speeds when the ef fect of the wings is reduced, was used by Rodriquez Cantieri Navali Spa to create the AL I SWATH .

The use of submerged bodies with bearing geometry in partial replacement of the wings is also a known technique .

Refer, for example , to the documents US2006169191A1 , W02009111629A1 , US2012291686A1 , US7004093 , EP1082252A1 , wherein di f ferent types of submerged bodies with bearing geometry are described .

In search of an ef ficient , new generation fairing, for an application on a series of passenger ferries o f variable length from 12 to 30 meters , the author has analysed and simulated the aforementioned types of hybrid fairings , veri fying that they present two main problems : high draft and, i f the submerged body i s navigated too close to the surface to limit dipping, the formation of a wave trough near the aft propeller .

A secondary problem is that the submerged body can generate a side thrust that prevents or reduces turning . The possibility of making it mobile , changing the angle of incidence in the two floors would al low better control of the flight altitude and the angle of en route , making the vessel more stable and manoeuvrable .

Another secondary problem encountered in vessels with a very large submerged body is the di f ficulty o f manoeuvring at low speeds . In fact , systems are known whereby, alongside the main axle line placed in the central body, auxiliary axle lines placed in the side hulls are added . In some cases those placed in the side hulls consist o f azimuthal sternfeet , as in the case o f the ALISWATH by Rodriquez Cantieri Navali .

However, creating a propulsion system consisting of three propellers in which the two side ones are used only for manoeuvring, while the central one is used for cruising speed is not simple .

I f the propellers are not designed correctly, there i s a risk that when they have to work together, the lateral ones will reduce the ef ficiency of the central one, and vice versa. For this reason, it would be better if the side propellers were used only for manoeuvring, and at cruising speed they were excluded, guaranteeing the turning by means of a small rudder.

The last problem, not entirely secondary for safety purposes, is that the configuration of the submerged- wing hydrofoil fairing and the "HYSWAS" and "ALISWATH" fairing is completely unstable when in flight and its structure needs to be continuously controlled electronically by flap actuation or similar devices.

It would be interesting to sacrifice a small part of the fairing efficiency in favour of safety by allowing the side hulls to be partially submerged in the flight phase (V) in order to allow both a minimum of dynamic shape stability and a gentle emergency splashdown.

The present invention manages to overcome the problems and meet the aforementioned requirements by creating a fairing in accordance with the preamble of the independent claim and in accordance with the characterizing part of the independent claim.

These and further objects of the present invention are achieved by a device according to the appended independent claim and the sub-claims, to be considered as an integral part of the present description.

The present invention is described by reporting some preferred examples of embodiment, by way of nonlimiting example, with reference to the attached figures .

Fig.l represents a cross section of the vessel where you can see the central body [1] , the central prop [2] , the central platform [3] , the side hulls [4] , the stabilising fins [5] , the stabilisation boxes [6] and the relative pumps [7] for their emptying and filling, the skid of the side hulls [8] .

Fig.2 represents the longitudinal view of the vessel where you can see the central body [1] , the central prop [2] , the central platform [3] , the side hulls [4] , the stabilising fins [5] , the skid [8] , the propeller [9] and the rudder [10] .

Fig.3 represents the floating section of the vessel at cruising speed, where you can see the central body [1] , the central prop [2] , the side hulls [4] , the stabilising fins [5] , the propulsion propeller [9] , the rudder [10] , the wings that convey the flow on the propeller to prevent it from being exposed in the wave trough [11] caused by the central body.

Figure 4 represents the floating section of the stationary vessel, where you can see the central body [1] , the central prop [2] , the side hulls [4] , the stabilising fins [5] , the propulsion propeller [9] , the rudder [10] , the wings that convey the flow on the propeller to prevent it from being exposed in the wave trough [11] caused by the passage of the body and the central prop.

Fig.5 represents the stern view of the vessel where you can see the tunnel [12] in which the propeller is arranged in order to prevent it from being exposed due to the wave trough produced by the passage of the central body.

Fig. 6 represents the longitudinal view of the vessel sectioned towards the stern at the ship's centreline, where you can see the tunnel [12] in which the propeller is arranged in order to prevent it from being exposed due to the wave trough produced by the passage of the central body. Fig. 7 represents the view from the stern of the vessel where you can see the two propellers to be used for the manoeuvre [13] and to be excluded during navigation.

Fig. 8 represents the longitudinal view of the vessel sectioned towards the stern at the centreline of the hulls, where you can see the opening and closing system of the side tunnel [14] to allow the flow of water to reach the two manoeuvring propellers [13] at low speed, or divert the flow in order to exclude the two manoeuvring propellers [13] at cruising speed.

Figures 9 and 10 represent a cross-sectional view of the vessel in which the central body [1] , the central prop [2] , the platform [3] , a linear guide between the central prop and the platform can be seen.

Figures 11 and 12 represent a cross-sectional view of the vessel in which the central body [1] , the central prop [2] , the platform [3] and a rotoidal guide [17] with rotation axis in the longitudinal direction, that is, in a direction parallel to the fore-and-aft axis of the vessel, located between the central prop and the platform.

Figures 13 and 14 represent a longitudinal view of the vessel in which you can see the central body [1] , the central prop [2] , the platform [3] , a rotoidal guide [18] with rotation axis in the transverse direction, that is perpendicular to the fore-and-aft axis, located between the central prop and the platform.

Figures 15 and 16 represent a top view of the vessel in which the central body [1] , the central prop [2] , the side hulls [4] , a rotoidal guide [19] with rotation axis in the vertical direction, that is, according to an axis perpendicular to the plane on which the platform [3] located between the central prop and the platform is arranged.

Figures 1 to 4 represent the section of a vessel consisting of a central body [1] , the central prop [2] , the platform [3] , the side hulls [4] . When the vessel is stationary, all the weight is supported by the hydrostatic thrust of the central body and the side hulls, and for this reason it is submerged at the floating altitude R (rest) , when the vessel begins to sail due to the hydrostatic thrust of the central body, it rises up reaching the floating altitude V (Flight) .

When the vessel is stationary, figure 4, the height of the platform with respect to the buoyancy surface is such that the side hulls have a sufficient buoyancy section to guarantee the support of the weight of the vessel by means of the sole hydrostatic thrust of the submerged body and the side hulls.

With the vessel in motion, figure 3, the submerged central body (torpedo) generates a hydrodynamic thrust such that the platform is brought to an altitude from the floating surface of the sea such that the side hulls have a minimum buoyancy section and their function only consists in that of stabilising the motions of the vessel, whose weight is supported only by the hydrostatic and hydrodynamic thrust of the submerged central body.

In Figures 3 and 4, respectively, when the vessel is stationary and at sea, the part depicted with the filling lines indicates the submerged part of the vessel .

It can therefore be noted, as in figure 4, that the submerged part of the vessel, in particular of the central and side hulls, is lower than the submerged part illustrated in figure 3.

During navigation, the side hulls, by diving, counteract the ship's movements, due to an increase in the hydrostatic thrust and the hydrodynamic thrust, making the vessel stable.

At the flight altitude, the total buoyancy section of the side hulls and the central body is still minimal, so the resistance to the advancement of the vessel is very low, as that component of resistance to the advancement is missing due to the displacement of the water and the formation of the waves typical of displacing vessels.

Despite the reduced section at the buoyancy, the load capacity of the vessel is guaranteed by the dimensions of the central submerged body, while the reduction and stabilisation of the ship's motions is guaranteed by the presence of the two side hulls, which, by dipping or raising, increase the hydrostatic thrust.

The operation described above is obtained thanks to the peculiar shape of the side hulls 4, which provides a tapered shape downwards, i.e. from the platform 3 in the direction of the vessel's waterline.

As illustrated in figure 1, the side hulls have a section along a plane perpendicular to the fore-and-aft axis of the vessel that provides a more rounded and larger part proximal to the platform 3, in order to taper downwards, presenting a part distal from the triangle-shaped platform 3.

With particular reference to figure 1, it is possible to note how the section of the side hulls, in addition to providing for a downward tapered course, present, before the abrupt change in width along the horizontal direction, perpendicular to the fore-and-aft axis, four flat surfaces, consisting of skids 8 that run parallel to the fore-and-aft axis of the vessel.

These skids 8 perform the function of surfaces, they perform the function of bearing hydrodynamic surfaces that by deflecting the flow of water generate a vertical force that in addition to the increase in hydrostatic force due to their volume, tends to make the vessel raise.

As the vessel increases in speed, it rises and comes out of the water, the skids 8 come out of the water and no longer give lift, but also no resistance.

The skids 8 are therefore functional only at low speed.

The skids 8 operate in a sequential manner.

At high speed, the skids 8 are used to reduce the ship motions (roll, heave, pitch) .

If the vessel rolls to the left, the skids of the left hull again enter the water and provide a lift that generates a straightening moment to the right.

The same happens if the vessel jumps.

This operation is particularly effective in combination with the presence of the central body 1.

To increase the ability to reduce ship motions and increase passenger comfort, stabilisation systems can be installed based on bearing surfaces, for example stabilisation fins [5] , connected to the submerged central body or to the side hulls, or submerged wings, or again based on compensation boxes to be filled or emptied depending on the trim of the vessel. As anticipated, one of the problems encountered in vessels with a very large submerged body is to cause a wave whose trough is located at the stern of the vessel, where the propulsion propellers are usually located. This means that the propellers can approach the free surface and even, in some cases, expose themselves, thus losing efficiency. Figure 4 shows how the wave trough caused by the passage of the submerged body tends to bring the sea surface closer to the apex of the propeller blade [9] and the rudder [11] . If the submerged body is retractable, such as the one shown in figures 10 and 12, i.e. it can be moved in a vertical direction driven by manual, hydraulic or electric actuators, sliding in a linear guide [16] , the problem of the wave trough can be solved by moving the central body downwards when the vessel is sailing. In practice, the central body can be kept raised when the vessel is stationary or manoeuvring at low speed, to ensure access to shallow water ports; in high speed navigation, the submerged body can be moved downwards, increasing its immersion and preventing the propeller from getting too close to the sea surface due to the effect of the wave trough generated by the passage of the body itself. Another way to prevent the propeller from being exposed in the wave trough is to duct the propeller .

In one version of the present invention, see Figures 5 and 6, the central body has a stern geometry such as to completely or partially wrap the propeller making it practically ducted. In the particular case, the tunnel or nozzle is an extension of the upper geometry of the body that overhangs the propeller and prevents the trough from exposing the propeller. The rudder can be positioned in the end part of the tunnel or nozzle, in an alternative version the end part of the tunnel or nozzle can act as a rudder by rotating around a vertical axis.

Figure 6 illustrates the shape of the tunnel that duct the propeller according to a possible embodiment and according to a longitudinal plane of the vessel, i.e. a plane parallel to the fore-and-aft axis and perpendicular to the floating plane of the vessel.

In addition or as an alternative to this tunnel or nozzle, diverters [11] can be installed that collect the water from the side trail and convey it towards the propeller, see figure 4 for this. In the particular case, the conveyors are fixed fins mounted perpendicular to the hull with an angle of incidence with respect to the flow such as to divert the water and make it converge towards the propellers.

In a constructive variant thereof of the present invention, the position of the submerged body can be modified by means of manual, hydraulic or electric actuators in order to vary not only its vertical position in a linear manner through a prismatic guide [16] , as in figure 9 and 10, but also through the variation of the angle of inclination in the three planes ZY (roll) figure 11 and 12, XZ (pitch) figure 13 and 14, XY (yaw) 15 and 16. In plane ZY, figures 11 and 12, the side position of the submerged body with respect to the median centre of gravity is varied, creating a straightening moment with respect to the longitudinal axis X of the ship. This straightening moment can be used to control and reduce the rolling motions. In plane XZ, figure 13 and 14, varying the angle of incidence of the flow with respect to the submerged body modifies the hydrodynamic lift of the central body and the point of application of its resultant , and creates a straightening moment with respect to the transverse axis of the ship Y, which can be used to reduce pitching motions ; In plane XY, figure 15 and 16 , varying the angle responsible for creating a side force that opposes the variation of route or increases it in the event of turning, generates a moment around the vertical axis Z of the vessel to improve manoeuvrability or route stability .

Based on what has been described and illustrated, the central submerged body 1 can be mounted on the platform 3 , so as to present one or more relative movements with respect to said platform, to be provided alternatively or in combination, in particular :

- an oscillation around the fore-and-aft axis of the vessel ,

- an oscillation with respect to an axis parallel to the hori zontal plane of the platform and perpendicular to the fore-and-aft axis of the vessel ,

- an oscillation with respect to an axis perpendicular to the hori zontal plane of the platform, a linear translation along the fore-and-aft axis of the vessel , a linear translation along a vertical axis and perpendicular to the hori zontal plane of the platform .

In a constructive variant of the present invention shown in figures 7 and 8 , the s ide hulls are equipped with a propeller [ 13 ] whose geometry is optimi zed only for low speeds , i . e . for manoeuvring . When the vessel gains speed, the geometry o f the hull is such as to hide the propeller from the incident flow, eliminating any ef fect of these propellers on the propulsion . To hide the propeller from the incident flow, the hull is equipped with a very marked variation of the stern geometry, in the vicinity of which the flow detaches to pass the propeller without hitting it . At the point of detachment of the confined flow [ 15 ] , fixed or movable deflectors ( flaps ) [ 14 ] or simply a plate that cuts the motion perpendicularly ( Interceptors or intruders ) can be added in order to facilitate the detachment of the confined flow from the bottom of the hulls . In the case of flaps , these can be more than one in number, so as to create a real continuous damper, which closes the access to the tunnel where the propeller is housed .

Alternatively, the bottom, locally, can be made "blindlike" , letting the water pass during the manoeuvring phase at low speed, and then making it flow in an almost neutral way as it increases .

With particular reference to Figure 1 , two floodable boxes 6 are illustrated, positioned inside the side hulls 4 .

These floodable boxes 6 are in communication with a hydraulic f illing/emptying circuit, made according to any of the ways known to the state of the art and which provides for the use of pumping means 7 aimed at inj ecting/extracting water or a fluid from the floodable boxes 6 .

The floodable boxes consist of two compartments obtained in the side hulls 4 capable of accommodating a certain amount of liquid .

The si ze of the floatable boxes 6 i s variable based on the si ze of the vessel and the side hulls 4 .

According to a possible embodiment , it is possible to provide that the filling water of the floodable boxes 6 is taken from the place of navigation (be it a basin, a channel, a river, a lake or a sea) of the vessel.

Preferably, according to the variant illustrated in Figure 1, the floodable boxes 6 are placed at the top of the side hulls 4, in order to optimise the amount of filling fluid taken/extracted from the floodable boxes 6 to increase the stability of the vessel.

INDEX

I . Central body

2. Vertical prop

3. Upper platform

4. Side hulls

5. Stabilising fins

6. Floodable boxes

7. System pumps of the floodable boxes

8. Skid

9. Central propeller

10. Rudder

II. Conveying wings

12. Propeller tunnel

13. Side manoeuvring propeller

14. Dampers

15. Stern edge

16. Linear guide for central prop

17. Rotoidal guide for central prop in the plane ZY

18. Rotoidal guide for central prop in the plane ZX

19. Rotoidal guide for central prop in the plane XY

Claims

1. Fairing for vessel characterized by having a submerged central body [1] and connected to an upper platform [3] located above said central body through a vertical central prop [2] , the central body being configured to generate a hydrodynamic thrust upwards when the vessel is in motion, due to its shape or by means of one or more wing surfaces and connected to it, such as to raise the vessel to a flight altitude, there being two side hulls [4] , also connected to the upper platform, the same presenting a floating figure and a volume that reduces significantly from the upper platform towards their lower keel, in such a way as to present a strong decrease near the flight altitude, in order to be able to continue to stabilise the motions of the vessel, resulting in a reduced increase in the total resistance to advancement .

2. Fairing as in claim 1, characterized in that it has a further motion stabilisation system, consisting of fixed or movable bearing surfaces [5] connected to the central body and/or to the side hulls.

3. Fairing as in claim 1, characterized in that it has a further motion stabilisation system consisting of floodable boxes inserted in the hulls [6] .

4. Fairing as in the preceding claims, wherein the decrease in the buoyancy figure is achieved in steps, by means of skids [8] placed below the side hulls, so as to increase the hydrodynamic thrust in the take-off phase due to their planing effect.

5. Fairing as in the preceding claims, characterized in that it has the submerged central body mounted in a retractable manner, in such a way that the vertical position can be varied in order to limit the draft and/or to prevent the wave trough from exposing the propeller.

6. Fairing as in the preceding claims, wherein said vertical prop is configured so as to allow oscillation of the central body according to at least one degree of freedom.

7. Fairing according to one or more of the preceding claims, wherein said vertical prop is configured so as to allow the oscillation of the central body according to all three angular degrees of freedom (roll, pitch and yaw) , in order to increase or reduce its vertical lift, or to increase or reduce its side force in order to make the vessel more manoeuvrable and stable.

8. Fairing as in the preceding claims, wherein the central body has a propulsion propeller [12] positioned at a compartment obtained in the stern of the central body [12] , which compartment is configured in such a way as to wrap the propeller and prevent it from being exposed in the wave trough .

9. Fairing as in the preceding claims characterized in that it has on the central body baffles [11] able to convey water towards the propeller and reduce the effect that tends to expose the propeller in the wave trough.

10. Fairing as in the preceding claims characterized in that the propulsion propeller is tractive and possibly counter-rotating.

11. Fairing as in the preceding claims characterized by having propellers [13] optimized for manoeuvring on the side hulls and systems [14] that trigger the detachment of confined flow, limiting the flow on the propellers to the cruising speed to avoid that these reduce the total propulsive efficiency since they are not optimized for this speed.