EP3261912B1 - Towing arrangement - Google Patents

Description

The present invention relates to ducted tractive cables used on a ship to tow a submersible body dropped at sea and the handling of these cables. It relates more particularly tractors trenches careened by means of scales or sections hinged together. It also applies to any type of streamlined elongated element intended to be at least partially immersed.

The context of the invention is that of a naval vessel or vessel intended to tow a submersible object such as a variable immersion sonar integrated in a towed body. In such a context, in the nonoperational phase the submersible body is stored on board the ship and the cable is wrapped around the drum of a winch for winding and unrolling the cable, that is to say to deploy and to retrieve the cable. Conversely, in the operational phase, the submersible body is immersed behind the ship and towed by the latter by means of the cable whose end connected to the submersible body is submerged. The cable is wound / unrolled by the winch through a cable guide device that guides the cable as shown in the documents US3379162 or WO2009060025 .

To obtain a high immersion at high towing speeds, the towing cable is streamlined which reduces its hydrodynamic drag and the vibrations generated by the hydrodynamic flow around the cable. The cable is coated with a segmented fairing composed of rigid hulls having shapes designed to reduce the hydrodynamic drag of the cable. The role of the sheath formed by the hulls is to reduce the wake turbulence produced by the movement of the cable in the water, when it is immersed in water and towed by the ship. The rigidity of the hulls is necessary for large dives accompanied by high towing speeds of at least 20 knots. The flexible fairings are only interesting for economically profiling chains or cables buoys subjected to marine currents or at worst towed at speeds of 6 to 8 knots. In the case of the use of rigid fairing elements, the segmentation of the fairing is necessary so that the cable can pass through the pulley-like guide elements, and so that it can withstand a lateral deflection of the cable in case of a change of course of the ship and so that it can be wound on the drum of a winch.

In normal operating state, the hulls are rotatably mounted around the longitudinal axis of the cable. It is indeed necessary that the hulls can rotate freely around the cable to be properly oriented relative to the flow of water. Each hull is, however, linked to its two neighbors axially and in rotation around the cable so as to be pivotable with respect to them about an axis parallel to the x-axis of a small maximum angle of the order of a few degrees. This inter-hull link allows in particular the fairing assembly to pass smoothly in all guide elements. As a result, the rotation of a hull causes a rotation of its neighbors and gradually that of all hulls. Therefore, both when the cable is deployed in the water and when it is wrapped around the drum, any change in orientation of one of the hulls, affects gradually all hulls careening the cable. Thus when the cable is deployed at sea hulls are naturally oriented in the direction of the current generated by the movement of the building. In the same way, the guide device is conventionally configured to guide and guide the hulls that pass through it so that they have a predefined orientation relative to the winch drum, all the hulls adopt as the cable goes up a single orientation relative to the drum, orientation that allows to wind the cable by keeping the scales parallel to each other in turn.

However, the Applicant has found that, when one comes winding the faired cable around the drum of a winch to recover the towed body, it happens occasionally that the fairing is strongly deteriorated or crushed at the time of its passage through the devices. guidance, which may make the entire sonar system unavailable. It may even happen that this deteriorates the guiding device. For example, some variable-immersion sonar systems installed on certain ships and operated in the normal way by military crews encounter problems of crushing hulls about once a year and sometimes much more often. This grinding can have limited consequences but can also degenerate, block the winch or damage it and lead to the unavailability of the entire towing system and therefore sonar.

An object of the present invention is to limit the risk of damage to the fairing of a towed cable.

To this end, the applicant firstly, in the context of the present invention, identified and studied the cause of this problem of crushing the hulls by observation of the ducted cable in operational situation and by modeling ducted cable in operational situation and different forces acting on it, including hydrodynamic and aerodynamic flows and gravity.

During the operational phase, the fairway cable is towed by the vessel and has a submerged end. Very often, the tow point of a cable or fairing is a point on a pulley at a certain height above the water. By towing point means the position of the fulcrum of the cable on a device on board the ship, which is closest to the submerged end of the cable or fairing respectively. As the ship advances, the drag moves away from the transom and disappears under the water a little further than the vertical point of the towing point. The length of ducted cable in an aerial situation is increased compared to the simple towing height above the water because the cable is inclined relative to the vertical. It is observed that the last hull which is still in engagement with the ship, that is to say the hull which is at the point of towing, often resting on the pulley or resting on a guidance device on board the ship , is correctly oriented in the direction of the flow, although it is well above the air (leading edge against the flow and trailing edge trolling.) The first keel in the water (it is ie the hull just immersed) is assumed to take a correct orientation in the flow coming from the speed of the ship (leading edge against the flow and trailing edge trolling) .But between these two remarkable hulls, the column The fairing can become twisted because it is exposed to vibrations, an insignificant flow of air and gravity in the air and under the effects of the sea, the towing conditions and the waves. torsion situations of this aerial column are regularly observed. twisting is caused by gravity as soon as the cable has moved away from the vertical, which necessarily happens to him as soon as the towing speed is sufficient. Under the effect of gravity, the fairing column between the towing point and the sea will twist on one side (in the air) and then straighten up (in the water). This is the nominal situation of the fairing column. This torsion is a function of the intrinsic stiffness of the fairing column but also the aerial length. A situation in which the aerial part of the fairing 2 is a little twisted, that is to say in torsion about the axis of the cable is represented on the Figure 1A . On the Figure 1A the vertical direction in the terrestrial reference is represented by the z-axis and the orientation of the section of certain hulls in zones A, B and C delimited by dotted lines is shown. In the situation represented on the Figure 1A , the last hull 3 in engagement with the ship is oriented vertically (trailing edge upwards) as shown in zone A. The hulls which are in the air between the pulley P and the surface of the S water are lying under the effect of gravity. In other words, as visible in zone B, the trailing edge of the hulls is oriented downwards (between the pulley P and the surface S of the water, the hulls have turned around the cable). On the other hand, the hulls in the water are rectified by the action of the water flow acting on the FO arrow as shown in the zone C (trailing and attacking edge located approximately at the same depth).

• annuler son demi-tour et revenir à sa position initiale en décrivant la rotation inverse de celle qui l'avait amenée à l'envers. Elle se trouve alors correctement orientée.
• ou ajouter au demi-tour existant un autre demi-tour qui la ramène à la bonne orientation dans le flux mais ce qui a pour conséquence de vriller de 1 tour (ou 360°) la partie aérienne du carénage au-dessus d'elle et de vriller de la même manière une portion en-dessous d'elle de un tour (ou 360° mais cette fois dans l'autre sens). La partie qui était initialement à l'envers est revenue à la bonne orientation dans le flux moyen lié à la vitesse du navire mais il s'est donc produit deux vrillages d'un tour l'un au-dessus dans l'air et l'autre en dessous dans l'eau. On parle de torsion complète du carénage (pouvant être traduite par twist en terminologie anglo-saxonne). Cette torsion complète est une situation stable de la colonne de carénage ou du carénage 2. Elle est représentée sur la figure 1B. Cette situation peut se décrire de la manière suivante : entre le point de remorquage R et la surface de l'eau S, la colonne de carénage effectue un tour complet dans le sens de la flèche F1 autour du câble. La colonne de carénage 2 traverse la surface S et reste correctement orientée sur une certaine longueur L de l'ordre de quelques mètres ou moins parfois. Puis la colonne de carénage 2 effectue un tour complet dans l'eau, en sens inverse, représenté par la flèche F2 pour revenir à la bonne orientation dans le flux. Autrement dit, le carénage subit une double torsion complète autour du câble. La double torsion comprend une torsion complète aérienne, situé au dessus de la surface de l'eau et un une torsion complète immergée, située en dessous de la surface de l'eau. Toute la partie du carénage située en dessous de cette double torsion complète n'est plus du tout affectée par ce qui se passe au-dessus d'elle (ses carènes sont correctement orientées dans le flux).

From time to time, depending on the sea conditions, packets of water or breaking waves fall more or less towards the transom of the ship, creating a momentarily inverse flow in the aerial part of the cable. which reigns lower and which corresponds to the speed of advancement of the ship. These water bodies are perfectly capable of further distorting the fairing column and placing it in opposition to the expected position in the normal towing flow. In this case, the fairing is twisted and performs, in its aerial part, a half turn around the cable. This means that two hulls of the aerial part of the fairing column, have trailing edges forming between them a 180 degree angle around the cable. The part of the fairing between these two hulls is twisted or twisted. From this situation, it may happen that these portions of fairings which are upside down in relation to the average flow given by the speed of the ship, are then suddenly bathed again by this average flow (because of the movement of the ship, that of the vaques, etc.) the part of fairing upside down is therefore requested to return in the right direction (related to the normal average flow). She can then:

• cancel her U-turn and return to her initial position by describing the reverse rotation of the one that had brought her upside down. It is then correctly oriented.
• or add to the existing U-turn another U-turn which brings it back to the correct orientation in the stream but which has the effect of twisting 1 turn (or 360 °) the aerial part of the fairing above it and to twist a portion below it one turn (or 360 ° but this time in the other direction) in the same way. The part that was initially upside down returned to the correct orientation in the average flow related to the speed of the ship but so there were two twists of a turn one up in the air and the other below in the water. We speak of complete torsion of the fairing (which can be translated by twist in English terminology). This complete twist is a stable situation of the fairing column or fairing 2. It is represented on the Figure 1B . This situation can be described as follows: between the towing point R and the surface of the water S, the fairing column performs a complete revolution in the direction of the arrow F1 around the cable. The fairing column 2 crosses the surface S and remains properly oriented on a certain length L of the order of a few meters or less sometimes. Then the fairing column 2 performs a complete turn in the water, in the opposite direction, represented by the arrow F2 to return to the correct orientation in the flow. In other words, the fairing undergoes a double complete twist around the cable. The double twist includes a complete air twist, located above the surface of the water and a complete submerged twist, located below the surface of the water. The entire part of the fairing located below this double complete twist is no longer affected by what is going on above it (its hulls are correctly oriented in the flow).

The configuration in which the fairing undergoes a double twist is stable but strongly degraded and it is likely to bring major disturbances to the entire system.

The Applicant has discovered that when a fairing undergoes a double complete torsion, under certain conditions, the fairing will be strongly deteriorated in the water and this deteriorated part will cause great damage to the ducted cable or even to the entire streamlined system. during winding of the cable and more specifically during its passage in the cable guide device.

By analyzing the double complete torsion, the Applicant has found that the submerged torsion can be considered as "hooked" on the cable. In other words, the position of the submerged torsion is fixed relative to the cable along the axis of the cable. On the other hand, its air counterpart, the aerial torsion, remains located at the same place between the point of towing R and the surface of the water S. It is not fixed with respect to the cable along the axis of the cable but fixed by relative to the surface S of the water or the point of towing. When the cable is hoisted up or down, hulls undergoing the submerged twist follow the movement of the cable that is hoisted up or down while the aerial twist remains fixed relative to the surface of the water. It follows that a course of the cable plunges the submerged torsion to a greater depth while the aerial torsion remains at the same place with respect to the surface of the water (the two torsions then move away from the one of the other). The figure 1C represents a situation in which the cable was unrolled in relation to the situation of the Figure 1B (see arrow). The distance L2 which represents the distance between the part of the fairing concerned by the submerged torsion and the point of entry of the fairing into the water is greater than the distance L1 which represents this same distance in the situation of the Figure 1B . Conversely, hoisting the cable, compared to the situation of the Figure 1B , according to the arrow represented on the figure 1D , makes up the submerged torsion while the aerial torsion remains always in the same place with respect to the surface of the water (the two torsions then approach one another).

One must then look at what happens for a twist of a submerged and towed ride as well. This torsion which unfolds on a low height forces the fairings to sail upside down or across the stream. The action of the flux on these hulls is then very important (proportional to the surface, the angle, the density of the water and the square of the speed) this action is translated by powerful pairs of torsion which tend to force the hulls to align themselves in the flow but they come up against the stiffness of the twisting turn which then increases. It then happens that a balance occurs and that the twist of a tower is terribly reduced in height and the fairing undergoes violent efforts that will tighten the torsion immersed under the effect of the towing speed. In other words, the complete turn of the fairing around the cable will take place over a shorter and shorter distance. Observations at sea have shown that the fairing column can perform a complete turn around the cable over a length of less than 50 cm. During the towing, the hydrodynamic flow exerts a very important torque on the hulls wrongly oriented which can go up to the deterioration of the fairing even to the complete rupture of the hulls.

During the recovery of a submerged torsion, the fairing was long and very strongly constrained, it kept the memory of its deformation (ie its twisting) and the submerged torsion comes out of the still very narrow water when hoisting and does not disappear when hoisting. We talk about residual torsion. Depending on the exposure time of the fairing to this submerged and towed torsion, the submerged torsion may become permanent or long enough to be absorbed, making it for a long time totally incapable of engaging in the cable guide device, although the continuity of the fairing is not broken. Side torsion air there is no damage, there is a twist applied but at no time it can damage the cable.

When the immersed torsion still very tight then presents itself to the guiding device, for example the pulley, the hulls affected by this immersed torsion can not be placed correctly in the guiding device, in particular in the pulley, they get stuck in the device guidance. It is then the whole fairing column that enters the guide device which is methodically destroyed if the hoist is continued because gradually, each hull follows the orientation of the one that precedes it. This situation can even lead to the breaking of the guiding device.

The invention proposes a guiding device configured so as to limit the risk of damaging the fairing of the cable.

$$\mathit{lid}=2\left(\mathit{LC}+E\right)\ast \sin \left(\mathit{\alpha s}\right)$$

$$\mathit{\alpha s}=\mathit{\alpha i}\ast \frac{R}{R-\mathit{CAR}}$$

où ai est un angle limite supérieur à 45° et inférieur à 90°, où R est le rayon de la poulie et où CAR est la distance maximale séparant le bord de fuite BF des carènes du carénage de l'axe de l'élément allongé prise parallèlement à la corde CO des carènes, où LC est la longueur de corde des carènes et E est l'épaisseur maximale des carènes,
dans lequel la première courbe est confondue avec la deuxième courbe en deux points extrêmes de la courbe de référence, la première courbe est en tout point compris entre chacun des points extrêmes et le fond confondue avec la deuxième courbe ou plus proche de l'axe de la poulie que la deuxième courbe selon le rayon de la poulie dans le plan radial.To this end, the subject of the invention is a towing assembly comprising an elongate element streamlined by means of a fairing comprising a plurality of hulls, the hulls comprising a channel intended to receive the elongated object and being shaped so as to reduce the hydrodynamic drag of the at least partially immersed elongated object, said hulls being pivotally mounted on the elongated member about the longitudinal axis of the channel, the towing assembly further comprising a towing and handling device for towing the elongated streamlined element while the latter is partially immersed, comprising a winch for winding and unrolling the streamlined elongated element through a guide device for guiding the elongate element, the guide device comprises a first groove whose bottom is formed by the bottom of the groove of a pulley, the first groove being delimited by a first surface having a concave profile in a radial plane of the pulley, the width of the first groove and the curvature of the profile of the first curved surface in the radial plane being determined so as to make it possible to tilt the hull, by rotation of the hull about the axis of the elongated member under the effect of the traction of the elongated member relative to the guide device along its longitudinal axis, from a returned position in which the hull is oriented trailing edge towards the bottom from the first groove to an acceptable position in which it is oriented leading edge towards the bottom of the first groove. Advantageously, the width of the first groove and the curvature of the profile of the first curved surface in the radial plane are determined as a function of the radius R of the pulley of the maximum length CAR, taken parallel to the rope separating the trailing edge of the hulls of the fairing of the axis of the elongated element, the maximum length of rope LC of the hulls and the maximum thickness E of the hulls. Advantageously, the guiding device comprises a first groove whose bottom is formed by the bottom of the groove of a pulley, the first groove being delimited by a first concave surface whose section in a radial plane of the pulley is a first curve. concave comprising the bottom coincides with the bottom of a second reference groove delimited by a second curved surface whose cross section in the radial plane BB is a reference curve in V, the opening of the V being at least equal to twice that of a threshold angle as and the width of the V lv, taken along a line d parallel to the axis of the pulley, is at least equal to a threshold width ls given by: $$\mathit{ls}=0.7*\mathit{lid}$$

$$\mathit{lid}=2\left(\mathit{LC}+E\right)*\sin \left(\mathit{.alpha.s}\right)$$

$$\mathit{.alpha.s}=\mathit{\alpha i}*\frac{R}{R-\mathit{BECAUSE}}$$

where ai is a limit angle greater than 45 ° and less than 90 °, where R is the radius of the pulley and where CAR is the maximum distance between the trailing edge BF of the hull of the fairing of the axis of the elongate member taken parallel to the CO rope of the hulls, where LC is the rope length of the hulls and E is the maximum thickness of the hulls,
in which the first curve coincides with the second curve at two extreme points of the reference curve, the first curve is in all points between each of the extreme points and the background coincides with the second curve or closer to the axis of the pulley as the second curve according to the radius of the pulley in the radial plane.

où Cf est le coefficient de frottement entre le matériau formant la partie extérieure de la queue de la carène et le matériau formant la surface délimitant la gorge de la poulie.Advantageously, the limiting angle α 1 is given by the following formula: $$\mathit{\alpha i}=\frac{\mathrm{<figure-callout\; id="4"\; label="\pi "\; filenames="imgf0002.png,imgf0005.png"\; state="\{\{state\}\}">\pi </figure-callout>}}{4}+\frac{1}{2}\mathit{arctan}\left(\mathit{Cf}\right)$$

where Cf is the coefficient of friction between the material forming the outer part of the tail of the hull and the material forming the surface defining the groove of the pulley.

Advantageously, the first groove is the throat of the pulley.

Advantageously, the first concave curve has a U-shaped profile between the extreme points

Advantageously, the hulls comprise a hull comprising a nose receiving the elongated element and comprising a leading edge a tail having a tapered shape extending from the nose and comprising a trailing edge, the first concave curve is defined in a radial plane of the pulley so that when the hull extends edge of attack perpendicular to the radial plane, whatever the position of a hull in the first groove, when the nose of the hull bears on the first concave curve and the elongated element exerts on the hull, in the radial plane , a plating force of the nose of the hull against the pulley, said plating force Fp comprising a component CP perpendicular to the axis of the pulley and a lateral component CL the trailing edge of the hull is not in contact with the first concave curve or is in contact with a part of the first concave curve forming, with a straight line dp of the radial plane perpendicular to the axis xa extending from the axis of the elongated element x to the trailing edge of the hull, an angle γ at least equal to a sliding angle αt. The slip angle is given by the following formula: $$\mathrm{\alpha }\mathrm{t}=\arctan \left(\mathrm{Cf}\right)$$

Where Cf is the coefficient of friction between the material forming the outer part of the tail of the hull and the material forming the surface defining the groove of the pulley.

• une courbe supérieure présentant un premier rayon de courbure R1 égal à ½* g*lid passant par le fond et dont le centre est situé sur une droite perpendiculaire à l'axe de la poulie passant par le fond,
• une courbe inférieure INF comprenant une portion centrale CENT s'étendant sensiblement parallèlement à l'axe de la poulie symétrique par rapport à un plan perpendiculaire au plan radial passant par le fond et s'étendant, le long de l'axe de la poulie sur une première largeur égale à g*lid et comprenant, de part et d'autre de la portion centrale CENT, des portions latérales LAT1 et LAT2 reliant la portion centrale aux points extrêmes 133, 134 et présentant un deuxième rayon de courbure R2 égal à 1/4*g*lid.

Advantageously, the first curve has a U-shaped profile and has a central zone, having a width equal to g * lid where lid is the ideal width and g is between 0, 7 and 1, between the extreme points coincides with the extreme points of the reference curve having a width equal to g * lid, the central zone delimited by the two following curves:

• an upper curve having a first radius of curvature R1 equal to ½ * g * lid passing through the bottom and whose center is located on a straight line perpendicular to the axis of the pulley passing through the bottom,
• a lower curve INF comprising a central portion CENT extending substantially parallel to the axis of the pulley symmetrical with respect to a plane perpendicular to the radial plane passing through the bottom and extending along the axis of the pulley on a first width equal to g * lid and comprising, on either side of the central portion CENT, side portions LAT1 and LAT2 connecting the central portion at the end points 133, 134 and having a second radius of curvature R2 equal to 1/4 * g * lid.

Advantageously, the hulls are rigid.

Advantageously, the fairing comprises a plurality of fairing sections, each fairing section comprising a plurality of hulls interconnected along the axis of the elongated member and hinged together, the fairing sections being free to rotate about the axis. of the elongated element relative to each other.

Advantageously, the fairing sections have respective heights along the axis of the channel, defined as a function of the angular stiffness k of the respective fairing sections, and as a function of the length of rope LC of said hulls of said respective sections so as to prevent the formation a complete twist on said respective sections.

où F est une constante comprise entre 250 et 500.Advantageously, the fairing sections have respective heights less than a maximum height hmax such that: $$\mathit{hmax}\le \frac{\pi *\mathrm{<figure-callout\; id="2"\; label="k\; F\; LC"\; filenames="imgf0001.png,imgf0007.png"\; state="\{\{state\}\}">k\; </figure-callout>}}{F{\mathit{LC}}^{}}$$

where F is a constant between 250 and 500.

Advantageously, at least one hull comprising a leading edge and a trailing edge, comprises a bearing edge comprising a first abutment abutment edge with respect to the leading edge, the first bearing edge being arranged of whereby the distance between the leading edge and the bearing edge, taken perpendicularly to the leading edge, decreases continuously, along an axis parallel to the leading edge, from a first end of the first edge of support to a second end of the first support edge, said hull being called beveled hull.

Advantageously, the support edge is arranged in such a way that the distance between the support edge and the leading edge decreases continuously, along an axis parallel to the leading edge, from the first end of the first edge. support to a first side face of the hull closer to the second end of the first support edge than the first end of the first support edge.

Advantageously, the support edge is the trailing edge.

Advantageously, the beveled hull is dimensioned so as to be more resistant to a pressure force applied in a direction perpendicular to the leading edge and connecting the leading edge to the trailing edge than the other hulls.

Advantageously, the beveled hull comprises two parts contiguous along the first bearing edge, the hull being configured to be kept in an expanded configuration when it is subjected to the hydrodynamic flow of water, the two parts being arranged, relative to each other around the first support edge, so that the hull has a trailing edge parallel to the leading edge and a constant section along the leading edge and configured to allow the relative pivoting between the two parts around the first support edge when a relative pivoting torque between the two parts applied around an axis formed by the first bearing edge exceeds a predetermined threshold so that the hull passes from the deployed configuration to a folded configuration around the support edge.

Advantageously, at least one of said sections comprises at least one end hull adjacent to a single other hull belonging to said section having a bearing edge comprising a first abutment edge with respect to the leading edge, the first support edge being arranged such that the distance between the leading edge and the first bearing edge, taken perpendicularly to the leading edge, decreases continuously, along an axis parallel to the leading edge, from a first end of the first support edge to a second end of the first support edge further from the other hull than the first end, along the axis parallel to the leading edge.

Advantageously, the hulls are rigid.

• la figure 1A déjà décrite représente un câble caréné, au moyen de carènes rigides liées axialement entre elles, remorqué partiellement immergé depuis sa partie immergée jusqu'à une poulie de guidage dans une situation dans laquelle le câble ne subit pas de double torsion, la Figure 1B représente le câble de la figure 1A dans le même état d'immersion (c'est-à-dire d'enroulement et de déroulement) que sur la figure 1A mais subissant une double torsion ; la figure 1C représente le câble de la figure 1A présentant la double torsion de la figure 1B dans une configuration dans laquelle le câble a été déroulé par rapport à la figure 1B ; la figure 1D représente le câble de la figure 1A présentant la double torsion de la figure 1B dans une configuration dans laquelle le câble a été hissé par rapport à la figure 1B,
• la figure 2 représente schématiquement un navire remorquant un objet remorqué au moyen d'un câble caréné,
• la figure 3 représente schématiquement une portion de câble caréné selon l'invention au moyen d'un carénage selon l'invention,
• la figure 4a représente une section d'une carène du carénage selon l'invention selon le plan de coupe AA représenté sur la figure 2, la figure 4b représente schématiquement une vue de côté de la carène de la figure 4a vue selon la flèche b,
• la figure 5 représente schématiquement un tronçon de câble caréné selon l'invention pénétrant dans une poulie de guidage du câble,
• sur les figures 6a à 6b, on a représenté des coupes d'une poulie selon l'art antérieur, selon la face latérale de la carène pénétrant bord de fuite vers le fond de la gorge, au moment où elle vient en appui sur la poulie (figure 6a) puis après lorsque le câble a été tiré vers la droite sur la figure 5 (figure 6b) c'est-à-dire que le câble a été hissé et que sa tension a écrasé la carène),
• sur la figure 7, on a représenté une coupe partielle selon un plan radial BB (voir figure 5) d'un exemple de poulie selon un premier mode de réalisation de l'invention ainsi qu'une courbe de référence,
• sur la figure 8a on a représenté schématiquement une section d'une poulie, selon un deuxième mode de réalisation de l'invention, dans un plan formé par une face latérale de la première carène entrant en contact avec la poulie (équivalent du plan M sur la figure 5) comprenant le point de contact avec la poulie , les figures 8b et 8c représentent des sections de la poulie selon des plans successivement occupés par la même face latérale de la carène lorsqu'on enroule le câble,
• sur les figures 9a et 9b on a représenté des sections, selon des plans radiaux, de deux exemples de poulies selon un troisième mode de réalisation,
• sur la figure 10 on a représenté schématiquement, dans un plan BB, des courbes inférieures et supérieures d'une première courbe en fond de baignoire,
• sur les figures 11a à 11c on a représenté, dans des plans successifs parallèles au plan M des sections de la poulie ainsi que les orientations successivement adoptées par la face latérale de la carène de référence lorsque l'on enroule le câble, la carène arrivant retournée sur la poulie de la figure 7,
• sur les figures 12a à 12c on a représenté schématiquement en vue de côté une carène selon un premier mode de réalisation de l'invention et une tronçon de carénage comprenant une carène selon l'invention pénétrant dans une poulie, en perspective (12a) en vue de côté à l'entrée dans la poule (figure 12b), en vue en coupe selon le plan M visible sur la figure 12a, en vue en coupe selon le plan Q visible sur la figure 12d,
• sur la figure 13, on a représenté schématiquement un exemple de carène selon un deuxième mode de réalisation de l'invention,
• sur la figure 14, on a représenté, dans un plan radial de la poulie une portion d'une première courbe concave respectant une caractéristique avantageuse de l'invention,
• sur la figure 15, on a représenté, un cercle construit par rapport à une carène et vérifiant la caractéristique avantageuse de l'invention.

Other features and advantages of the invention will appear on reading the detailed description which follows, given by way of non-limiting example and with reference to the appended drawings in which:

• the Figure 1A already described is a streamlined cable, by means of rigid hulls axially connected to each other, towed partially immersed from its submerged portion to a guide pulley in a situation in which the cable does not undergo a double twist, the Figure 1B represents the cable of the Figure 1A in the same state of immersion (ie winding and unwinding) as on the Figure 1A but undergoing a double twist; the figure 1C represents the cable of the Figure 1A presenting the double twist of the Figure 1B in a configuration in which the cable has been unrolled in relation to the Figure 1B ; the figure 1D represents the cable of the Figure 1A presenting the double twist of the Figure 1B in a configuration in which the cable has been hoisted relative to the Figure 1B ,
• the figure 2 schematically represents a vessel towing a towed object using a fairway cable,
• the figure 3 schematically represents a ducted cable portion according to the invention by means of a fairing according to the invention,
• the figure 4a represents a section of a hull of the fairing according to the invention according to the cutting plane AA shown in FIG. figure 2 , the figure 4b schematically represents a side view of the hull of the figure 4a view according to arrow b,
• the figure 5 schematically represents a section of ducted cable according to the invention penetrating a cable guide pulley,
• on the Figures 6a to 6b , there is shown sections of a pulley according to the prior art, according to the lateral face of the hull penetrating the trailing edge towards the bottom of the groove, at the moment when it bears on the pulley ( figure 6a ) then after when the cable was pulled to the right on the figure 5 ( figure 6b that is, the cable was hoisted and its tension crushed the hull),
• on the figure 7 , there is shown a partial section along a radial plane BB (see figure 5 ) of an exemplary pulley according to a first embodiment of the invention as well as a reference curve,
• on the figure 8a schematically shows a section of a pulley, according to a second embodiment of the invention, in a plane formed by a lateral face of the first hull coming into contact with the pulley (equivalent of the plane M on the figure 5 ) including the point of contact with the pulley, the Figures 8b and 8c represent sections of the pulley according to plans successively occupied by the same lateral face of the hull when the cable is wound,
• on the Figures 9a and 9b there are shown, in radial planes, two examples of pulleys according to a third embodiment,
• on the figure 10 diagrammatically, in a plane BB, lower and upper curves of a first curve in the bath floor,
• on the Figures 11a to 11c in successive planes parallel to the plane M, sections of the pulley have been represented, as well as the orientations successively adopted by the lateral face of the reference hull when the cable is wound up, the hull arriving returned on the pulley of the figure 7 ,
• on the Figures 12a to 12c is schematically shown in side view a hull according to a first embodiment of the invention and a fairing section comprising a hull according to the invention penetrating into a pulley, in perspective (12a) in side view at the entrance in the chicken ( figure 12b ), in sectional view along the plane M visible on the figure 12a , in sectional view along the plane Q visible on the figure 12d ,
• on the figure 13 schematically shows an example of a hull according to a second embodiment of the invention,
• on the figure 14 there is shown, in a radial plane of the pulley, a portion of a first concave curve respecting an advantageous characteristic of the invention,
• on the figure 15 , there is shown a circle constructed with respect to a hull and verifying the advantageous characteristic of the invention.

From one figure to another, the same elements are identified by the same references.

The invention relates to a fairing intended to coat an elongate object, for example a flexible object such as a cable or a rigid object such as a drilling column at sea, intended to be at least partially immersed. The elongated element is conventionally intended to be towed by a floating building. The fairing is intended to reduce the forces generated by the current on this elongated element when it is immersed in water and towed in water by a naval vessel.

The invention also relates to a towing assembly as shown in FIG. figure 2 , comprising an elongated element 1 streamlined by means of a fairing according to the invention. In the rest of the text, the invention will be described in the case where the elongated element is a cable but it applies to other types of elongated flexible elements.

The cable 1 tows a towed body 101, comprising for example one or more sonar antennas. The towed body 101 is mechanically secured to the cable 1 as appropriate. The launching and the removal of water from the towed body 101 is carried out by means of a winch 5 arranged on a deck 103 of the ship 100.

• Un treuil 5 permettant d'enrouler et de dérouler le câble 1 caréné,
• un dispositif de guidage 4 permettant de guider le câble 1, le dispositif de guidage est disposé en aval du treuil vu de l'extrémité destinée à être immergée 6, du câble 1. Autrement dit, le câble 1 est enroulé autour du treuil 5 (ou déroulé au moyen du treuil) au travers du dispositif de guidage 4.

The towing assembly according to the invention also comprises a device for towing and handling the streamlined cable comprising:

• A winch 5 for winding and unrolling the streamlined cable 1,
• a guide device 4 for guiding the cable 1, the guide device is disposed downstream of the winch seen from the end intended to be submerged 6, the cable 1. In other words, the cable 1 is wound around the winch 5 ( or unrolled by means of the winch) through the guiding device 4.

The guiding device 4 is advantageously mounted on a support structure 7 intended to be fixed to the vessel that can be tilting or fixed.

The guide device guides the cable 1, that is to say to limit the lateral movement of the cable relative to the winch, in a direction parallel to the axis of rotation of the winch drum. It is also advantageously configured to modify the direction of the cable between its end intended to be immersed 6 and the winch 5 in a plane substantially perpendicular to the axis of the winch while allowing to secure the radius of curvature of the cable so that it do not go below a certain threshold in this plan.

In the non-limiting example shown on the figure 3 , the guiding device is a pulley 4. The guiding device may further comprise, inter alia, a fairlead for securing the radius of the cable, and / or a cutting device for storing the cable correctly on the drum and / or at least one deflector forming a surface for changing the orientation of a hull relative to the deflector by rotating the hull around the axis of the cable under the effect of the traction of the cable during its winding / unfolding. This can be done by a pulley.

On the figure 3 schematically shows a cable portion 1 coated with a fairing 11 according to the invention. This fairing 11 comprises a plurality of fairing sections 12a, 12b. Each fairing section 12a, 12b comprises a plurality of hulls 13, 13a. On the figure 3 two fairing sections 12a and 12b each comprising five fairing fairings are shown, but in practice the fairing may comprise many more fairing sections comprising many more hulls.

The hulls are advantageously rigid. By rigid hulls, it is understood in the present patent application that the hulls are configured so as not to deform substantially under the effect of the hydrodynamic flow, when immersed and possibly towed in the direction of the leading edge. In other words, the hulls retain substantially the same shape when subjected to the hydrodynamic flow. The hulls may possibly deform under the effect of efforts greater than those developed by the hydrodynamic flow. They are for example made of hard plastic material such as polyethylene terephthalate (PET) or polyoxymethylene (POM).

Each hull 13, 13a has a hydrodynamic profile, of the type of that represented on the figure 4a , in a plane AA perpendicular to the axis x of the cable (or axis of the channel 16). In other words, each hull 13, 13a is profiled so as to reduce the hydrodynamic drag of the cable 1 when the cable 1 is towed. The hulls 13a are hulls having the same characteristics as the hulls 13 but may differ from the hulls 13 by the characteristics which are explained later because of their position in the sections 12a, 12b. Each hull 13 comprises a wide nose 14 intended to receive the cable 1 and a tail 15 having a tapered shape extending from the nose 14. The nose 14 houses a channel 16 with an axis perpendicular to the plane of the sheet, intended for receive the cable 1. The nose 14 comprises the leading edge BA and the tail 15 comprises trailing edge BF which are the end points of the hull 13 in the plane of section. The hull 13 presents more particularly in this plane a profile in the form of a wing. The profile of the hull allows a less turbulent flow of water around the cable. The hydrodynamic profile has, for example, a droplet shape or a NACA profile, that is to say a profile defined by NACA which is an acronym for the English expression "National Advisory Committee for Aeronautics".

On the figure 4b , there is shown a view of the hull according to the arrow B, which is the same view as on the figure 3 . The hull has an elongate shape from the leading edge BA to the trailing edge BF. Viewed from the side, the hull 13 has a substantially rectangular shape delimited by the trailing edge BF and the leading edge BA parallel to the xc axis of the channel 16 and connected by two lateral faces 17, 18. The lateral faces 17, 18 extend substantially perpendicular to the leading edge BA. The lateral faces are arranged at the respective ends of the channel 16.

On the figure 4a , reference is made to the length of rope LC of the hull 13 which is the maximum length of the line segment called rope CO connecting the trailing edge BF and the leading edge BA of the hull 13 in a direction perpendicular to the axis of the xc channel. In other words, the rope is the line segment connecting the extreme points of a section of the hull. The maximum thickness E of the hull is the maximum distance separating the first longitudinal face 22 of the second longitudinal face 23 in a direction perpendicular to the rope CO in the plane of section of the hull. On the embodiment of the figure 4b the distance between the trailing edge and the leading edge is constant along the axis of the xc channel parallel to the leading edge BA. The length of rope is this distance. The longitudinal faces 22 and 23 extend parallel to the leading edge BA.

The hulls 13 are intended to be mounted on the cable 1 so as to be pivotable about the longitudinal axis of the cable 1, that is to say around the longitudinal axis of the channel 16.

The hulls 13 belonging to the same fairing section 12a or 12b are interconnected by means of a coupling device 20 allowing relative rotation of said hulls 13 relative to each other around the cable 1. The coupling device 20 binds the hulls between them both axially, that is to say along the towing cable but also in rotation around the cable 1. The coupling device 20 allows the relative rotation of the hulls relative to each other around the cable axis, that is to say the channel 16. This clearance is allowed either freely or with a stop. The rotation of a hull around the cable does not then cause the adjacent hull in rotation. The displacement can be obtained in a constrained manner with a more or less strong return to the aligned position (no relative rotation of the hulls relative to each other around the cable). In the latter case, the rotation of a hull around the cable rotates the adjacent hulls of the same section around the cable. Advantageously, the clearance between the adjacent hulls is substantially zero, so that any relative rotation between the hulls involves the elastic deformation of the coupling device. This allows the hulls of the same section to adopt an orientation relative to the cable allowing it to oppose the lower resistance to the current caused by the movement of the cable in the water. The coupling device allows this relative rotation with a maximum amplitude, that is to say a maximum angular displacement. In this way, the rotation of a hull causes a rotation of the neighboring hulls and gradually that of all hulls of the same section 12a or 12b. All the hulls of the same section adopt, as the rope rises, the same orientation relative to the drum, which enables the cable to be wound up while keeping the scales parallel to one another in turn.

Advantageously, the coupling device 20 allows relative rotation of the hulls relative to each other so as to allow the winding of the cable around a winch, the lateral deflection of the cable due for example to changes of course of the ship . The coupling device allows these relative rotational movements of the hulls relative to each other with maximum respective angular deflections. The coupling device 20 shown on the figure 3 , comprises a plurality of individual coupling devices 19, comprising for example a splint, each making it possible to connect a hull to a hull adjacent to said hull, that is to say to couple the hulls of the same section two together. In other words, each individual coupling device makes it possible to connect a hull to another hull adjacent to said hull only. The adjacent hulls form pairs of hulls. The hulls of the respective hull pairs of the same fairing section are connected by means of separate individual coupling devices. The coupling device thus makes it possible to individually connect each hull of a fairing section to each of its adjacent hulls. Advantageously, the individual coupling devices are configured so as to deform elastically during the relative rotation of the hulls around the cable. This is a twist of the individual coupling devices.

Advantageously, the hulls 13 are immobilized in translation relative to the cable 1 along the axis of the cable x. This makes it possible to prevent the hulls 13 from settling or distancing themselves along the cable 1, which could lead to problems with locking the fairing 11 during the winding of the faired cable around the drum of the winch 5 or even at the passage of the guiding device 4. For this purpose, each fairing section 12a, 12b comprises an immobilizing device 21 cooperating with a hull 13a of said section 12a, 12b and intended to cooperate with the cable 1 so as to immobilize the hull 13a in translation along the axis of the cable. On the realization of the figure 3 , the hull 13a is the hull farthest from the end intended to be submerged 6 located in the direction of the arrow f (called hull of head). The hulls being interconnected, the blocking achieved by the immobilizing device on a hull 13a has repercussions on the other hulls of the same section. The installation of an immobilization device by hull is not necessary which limits the costs and time of assembly and the weight of the streamlined cable. In a variant, the section comprises several immobilization devices each cooperating with a hull of the section. The immobilizing device comprises for example a ring 21 fixed to the cable by crimping and cooperating with the hull 13a in order to immobilize it in translation relative to the cable along the x-axis of the cable 1.

According to the invention, the fairing sections 12a and 12b are free to rotate, relative to one another, about the axis of the channel 16, that is to say around the axis of the cable 1 when they are mounted on the cable 1. In other words, the hulls 13, belonging to two separate fairing sections 12a and 12b are free to rotate relative to each other, around the axis of the channel, that is to say around the cable 1. Each section 12a, 12b is relatively flexible in rotation around the cable even if one observes a certain stiffness in torsion. This flexibility only increases with the length deployed. For this reason, the fact of cutting the fairing in free fairing section in rotation relative to each other limits the risk of formation of double twists, and thus to limit the risk of deterioration of the fairing, since the torsions of the sections fairing are not transmitted from one section to the other. The fairing can be installed along the cable. In other words, the fairing extends over the entire length of the cable. In a variant, the fairing extends along the cable for a length less than the length of the cable.

The fairing is for careening an elongated element. It is also intended to be towed by means of a towing device as described in this patent application.

The heights h, respective fairing sections, that is to say their lengths along the x-axis of the cable, are less than a maximum height hmax. Alternatively, at least one of the sections has a height less than this maximum height hmax. On the figure 3 the two sections have the same length but it is not an obligation. The maximum height hmax is chosen so as to be sufficiently small to prevent the formation of a complete air twist on the section, for example a complete torsion on the section. The disturbed section can make a complete turn on itself and realigns itself in the flow, since it is decoupled from its neighbors this section does not disturb them more and there is no longer any aerial torsion or immersed torsion. This configuration makes it possible to prevent any complete immersed twists from entering the guiding device and thus limit the risk of deterioration of the fairing. Moreover, this configuration makes it possible to avoid having to set up a monitoring procedure, by the crew, or a monitoring device intended to detect submerged twists, as well as a mechanical or manual procedure aimed at absorbing a double torsion detected or intended to assist immersed immersed torsion exiting the water to penetrate the guiding device without causing damage.

Où k est la raideur angulaire en torsion du tronçon de carénage angulaire en torsion autour de l'axe du câble (ou du canal) exprimée en Nm²/radians, h est la hauteur du tronçon de carénage, c'est-à-dire la longueur du tronçon de carénage selon l'axe du câble ou l'axe longitudinale du bord d'attaque.A fairing section T undergoing torsion at an angle θ around the x-axis of a cable (or channel 16) is subjected to an applied torque C around the x-axis of the cable 1. The torque C that makes it possible to obtain this angle of torsion is given by the following formula: $$C=\frac{\mathit{k\theta }}{h}$$

Where k is the torsional angular stiffness of the angular fairing section in torsion around the axis of the cable (or channel) expressed in Nm ² / radians, h is the height of the fairing section, that is to say the length of the fairing section along the axis of the cable or the longitudinal axis of the leading edge.

Où F est une constante calculée suivant une configuration qui a été identifiée comme étant la plus contraignante et qui tient compte du flux et du reflux du sillage et LC est la longueur de la corde des carènes du tronçon de carénage.The maximum height hmax depends on the torsional stiffness of the fairing sections. More fairing sections have a significant stiffness around the axis of the cable and they can have a high height. The longer the length of the fairing rope is important and the more the fairing section will be disturbed by the stresses of the sea and the towing conditions, the lower the maximum height of the fairing sections. The torsional disturbances caused by the stresses of the sea and the conditions of towing are proportional to the surface of the hulls of the section (thus to the length of rope) and to the lever arm (thus to the length of rope of the fairing). The maximum height hmax is therefore given by the following formula: $$\mathit{hmax}\le \frac{\pi *\mathrm{<figure-callout\; id="2"\; label="k\; F\; LC"\; filenames="imgf0001.png,imgf0007.png"\; state="\{\{state\}\}">k\; </figure-callout>}}{F{\mathit{LC}}^{}}$$

Where F is a constant calculated according to a configuration which has been identified as being the most restrictive and which takes into account the flow and ebb of the wake and LC is the length of the hull rope of the fairing section.

The constant F is between 250 and 500. F depends on the maximum speed at which it is desired to tow the cable. If you want to tow the cable at a speed of 20 knots, F is fixed at 400. F is lower if the maximum speed decreases.

Typically, for shrouds having an angular torsion stiffness k of the order of 4 to 5 Nm ² / rad, and a rope length LC of 0.125m, the maximum height and of the order of 2m if the constant is fixed at 400.

The fairing according to the invention has advantages even in the case where it is not sought to wind the cable around a winch. Indeed, the fact that the fairing according to the invention minimizes the risk of formation of Double twists makes it possible to limit the risks of deterioration of the fairing associated with the aging of the submerged torsions without they penetrate into a guiding device. The fairing according to the invention therefore limits the requirements in terms of maintenance of the cable.

Advantageously, the guide device of the towing assembly according to the invention is configured so as to make it possible to modify the orientation of a hull of the fairing relative to the guide device by rotation of the hull around the axis of the hull. cable, under the effect of the traction of the cable relative to the guide device (along the axis of the cable), when the hull has an orientation in which it bears on the guide device and in which the line of The action of force exerted by the cable on the guide device extends substantially in the direction extending from the axis of the cable to the trailing edge of the hull.

Advantageously, the guiding device is configured to turn a hull from an inverted position in which it is oriented tail down to an acceptable position in which it is oriented tail upwards. The up and down orientations are defined relative to a vertical axis related to the winch.

These configurations facilitate the winding of the streamlined cable on the winch. Indeed, when one comes winding the cable around the drum of the winch, the first hull of each section out of the water back to the guide device and, not being related to the hulls of the previous section, it goes to turn back trailing edge down under the effect of gravity dragging with it the following hulls of the same section of fairing. If the guide device does not allow such a reversal, the hulls will arrive misdirected on the winch drum (it is preferred to wind the hulls trailing edge upwards to avoid deterioration of the fairing because the leading edge is more resistant ).

For this purpose, the guide device comprises a guide or a set of guides for the change of orientation or tilting of the hull. This guide or guide assembly may for example comprise a pulley and / or a deflector or any other device for changing the orientation of the hulls around the axis of the cable. A non-limiting example of this type is described in the French patent application published under the number FR2923452 . These devices are conventionally arranged upstream or downstream of the pulley seen from the winch. They are conventionally concave, that is to say the type groove, so as to define a housing for receiving the hull to ensure its tilting. These guides may be able to follow the cable in case of lateral movement of the cable parallel to the axis of the pulley (or winch), being for example pivotally mounted about a substantially vertical axis.

So far all the towing pulleys are configured to move the keels nose to the bottom of the groove and tail to the outside of the groove. This arrangement is logical since the towing cable, effort seat, is necessarily housed in the nose of the hulls, that is to say near the leading edge. All towing pulleys then have a narrow V-shaped groove. This provision is made necessary because of the links between all the hulls. Leaving the sea and arriving at the towing pulley, hulls that, during their flight, have a tendency to move towards the trailing edge downwards (so upside down) are thus gradually recovered. thanks to the inter-keel links. When a hull is well positioned in the throat of the pulley, during hoisting (but also the reeling) all the following will gradually recover and move the pulley better.

Furthermore, devices for reversing the fairing (or rectifiers) are poor performance when installed downstream of the pulley, seen from the free end of the cable because the position of the cable has at this location at least two degrees of freedom: longitudinal and lateral and the current rectifier devices are not able to correctly follow the cable in these two directions or it is complex devices.

In the case of a V-shaped narrow-sheave pulley, if the guiding device is devoid of a device for reversing downstream of the pulley seen from the free end of the cable or if this device is not performing hulls entering tail down in the pulley will be able to get stuck in the groove and, if they are not dimensioned to resist the force exerted by the cable in this orientation, they will deform and cause the deformation of the following hulls. This situation is represented on the figures 5 and 6a to 6b . On the figure 5 , there is shown a portion of a ducted cable 1 penetrating a pulley P groove 50. In this figure, the cable 1 is wound which then enters the pulley in the direction of the arrow. Sure this figure, the axis xp of the pulley is perpendicular to the plane of the sheet. The hulls 13 of a first group of hulls 12a are oriented trailing edge BF to the outside of the groove and leading edge to the groove. The remarkable hull 13a is the leading hull of the section 12b, that is to say the hull 13a of the section 12b which is furthest from the end of the cable intended to be immersed 6. The hull 13a is presented at the pulley P trailing edge BF towards the groove of the pulley and leading edge BA towards the outside of the groove. This remarkable hull 13a belongs to a second group of hulls 12b.

If the pulley P is a pulley of the prior art, the section of the pulley of the prior art in the plane M passing through the side edge 18 connecting the trailing edge BF and the leading edge BA of the hull of head is such as visible on the figure 6a . The figure 6b a section of the pulley P of the prior art in another plane comprising the lateral edge 18 of the head hull 13a located to the right of the plane M on the figure 5 because the cable 1 has been hoisted, that is to say pulled according to the arrow represented on the figure 5 enter here figure 5 and the figures 6b , advancing the remarkable hull 13a in the throat. The groove of the pulley has a V-shaped section having an opening of between 20 ° and 50 °. The bottom of the V has a shape substantially complementary to the leading edge so that when a hull enters the leading edge pulley, the following hulls related to this hull will also take this orientation during the winding cable. On the other hand, if a head hull 13a reaches the trailing edge towards the groove 105 as is the case on the figure 6a , the groove is too narrow for the hull to turn back trailing edge under the effect of pulling the cable relative to the throat of the pulley along its axis. The cable tension forces the hull 13a to go down to the bottom of the groove. Indeed, when pulling the cable along its axis in the pulley, it develops a force, on the hull, oriented along the force action line indicated by the arrow on the figure 6a . However, if the hull is not dimensioned to resist this constraint, it is deformed and breaks (or deteriorates) as represented on the figure 6b .

In order to overcome these disadvantages, the invention aims to entrust a function of turning the hulls around the axis of the cable to the pulley itself.

For this purpose, the invention consists in providing a towing assembly comprising a device for guiding the cable disposed downstream of the winch as seen from the end of the cable intended to be immersed, the guiding device comprising a first groove whose bottom is formed by the bottom of the groove of a pulley, the first groove being configured to allow to tilt a hull of the fairing, by rotation of the hull around the axis of the cable x under the effect of the tension of the cable, from an inverted position in which the hull is oriented trailing edge (or tail) towards the bottom of the first groove, to an acceptable position in which it is oriented leading edge (or nose) to the bottom of the first throat, that is to say the trailing edge towards the outside of the throat. The dimensions and the shape of the profile of the first groove, in particular, the width of the first groove and the curvature of the profile of the first curved surface (which will be defined later) in the radial plane are determined according to the radius R of the pulley of the maximum length CAR, taken parallel to the rope separating the trailing edge BF from the fairing hulls, from the x-axis of the elongate element 1, from the LC rope length of the hulls and from the maximum thickness E of the hulls so as to tilt the hull from the returned position to the acceptable position.

When the trailing edge (or tail) is oriented towards the bottom of the first groove, this means that the trailing edge (or the fine end of the tail) is located at a distance smaller than the leading edge ( or that the nose) of the axis of the pulley xp. The axis of the pulley is the axis around which pivots the pulley relative to the winch, that is to say with respect to the fixed part of the winch. Advantageously, the axis of the pulley is substantially horizontal, that is to say intended to extend parallel to the surface of the water by calm sea state when the towing device is attached to a ship or ship . The bottom 26 of the groove of the pulley forms a circle of radius R whose center is on the axis of the pulley.

On the figure 7 , there is shown a section of the pulley P of the figure 5 in the radial plane BB of the pulley P, in the case where the pulley P is a pulley according to a preferred embodiment of the invention. A radial plane of a pulley is a plane which is formed by a radius r of the pulley and the axis xp of the pulley around which the pulley pivots. The radius r has a length R.

The first groove 24 is delimited by a first surface whose cross section in the radial plane BB is the first concave curve 25 (U-shaped curve shown in bold on the figure 7 ). The first concave curve 25 comprises a bottom 26 of the first groove 24. The bottom is the point of the first groove 24 which is closest to the axis xp of the pulley.

On the figure 7 a reference curve 28 in V is also shown. The reference curve 28 in V is the section, in the radial plane BB, of a second curved surface delimiting a second reference groove 29 or second virtual groove. The bottom of the second groove, that is to say the bottom of the reference curve 28 is the bottom 26. The bottom V is the point of intersection of the two legs 31, 32 of V.

Où $$\mathit{lid}=2\left(\mathit{LC}+E\right)\ast \sin \left(\mathit{\alpha s}\right)$$

$$\mathit{\alpha s}=\mathit{\alpha i}\ast \frac{R}{R-\mathit{CAR}}$$

lid est une largeur idéale du V,
où αi est un angle limite supérieur à 45° et inférieur à 90°, où R est le rayon de la poulie et où CAR (représentée sur la figure 4a) est la longueur maximale, séparant le bord de fuite BF des carènes du carénage de l'axe du câble, prise parallèlement à la corde CO des carènes, où LC est la longueur de corde des carènes et E est l'épaisseur maximale des carènes.According to the invention, the opening of the V αv is at least equal to twice a threshold angle αs and the width of the V lv, taken along a straight line d parallel to the axis of the pulley, is at least equal to one threshold width ls given by: $$\mathit{ls}=0.7*\mathit{lid}$$

Or $$\mathit{lid}=2\left(\mathit{LC}+E\right)*\sin \left(\mathit{.alpha.s}\right)$$

$$\mathit{.alpha.s}=\mathit{\alpha i}*\frac{R}{R-\mathit{BECAUSE}}$$

lid is an ideal width of the V,
where αi is a limit angle greater than 45 ° and less than 90 °, where R is the radius of the pulley and where CAR (represented on the figure 4a ) is the maximum length, separating the trailing edge BF from the fairing of the cable axis, taken parallel to the CO rope of the hulls, where LC is the rope length of the hulls and E is the maximum thickness of the hulls .

In a preferred embodiment of the invention, the width of the V is at least equal to lid. The turnaround is then easier.

où Cf est le coefficient de frottement entre le matériau formant la partie extérieure de la queue de la carène et le matériau formant la surface délimitant la gorge de la poulie. Le matériau formant la partie extérieure de la queue de la carène est le matériau formant la carène lorsqu'elle est réalisée dans un unique matériau.Advantageously, the limiting angle αi is given by the following formula: $$\mathit{\alpha i}=\pi /4+\frac{1}{2}\mathit{arctan}\left(\mathit{Cf}\right)$$

where Cf is the coefficient of friction between the material forming the outer part of the tail of the hull and the material forming the surface defining the groove of the pulley. The material forming the outer part of the tail of the hull is the material forming the hull when it is made of a single material.

On the realization of the figure 7 the first curve 25 coincides with the second curve 28 at the end points 33, 34 of the second curve 28. The end points 33, 34 of the second curve are the points of the second curve which are spaced from the width lv according to a straight parallel to the axis of the pulley xp. They delimit the first groove and the second groove along an axis parallel to the axis of the pulley and along an axis parallel to the radius of the pulley passing through the bottom 26. The first curve 25 is at all points between each of the points 33, 34 and the bottom 26, coincides with the second curve or closer to the axis of the pulley xp than the second curve according to the radius of the pulley in the section plane BB.

Therefore, to ensure the desired inversion the first concave curve 25 delimiting the first groove 24 may have the profile visible on the figure 7 or be between the end points, at any point other than the bottom and the end points 33, 34, under the curve 28 and at least at a distance from the axis equal to the distance separating the bottom pulley pulley axis (Radius R pulley). In other words, the first concave curve is located in all points in the space delimited by the curve 28, the line d1 parallel to the axis passing through the bottom 26 and the lines d3 and d4 parallel to the radius r passing through the points 33 and 34.

The first concave curve 25 is the curve delimiting the first groove 24 intended to receive the ducted cable in a radial plane (see FIG. figure 7 ).

On the figure 14 a portion 250 of a first concave curve respecting an advantageous characteristic of the invention is shown in broken lines in a radial plane. The hull 13 extends leading edge perpendicular to the radial plane. This characteristic is as follows: the first concave curve is defined in a radial plane BB of the pulley so that when the hull extends leading edge BA perpendicular to the radial plane BB, whatever the position of a hull in the first groove 24, when the nose 14 of the hull 13 bears on the first concave curve and the cable 1 exerts on the hull 13, in the plane radial, a plating force of the nose of the hull against the pulley, said plating force Fp comprising a component CP perpendicular to the axis of the pulley and a lateral component CL (that is to say parallel to the axis of the pulley) the trailing edge BF of the hull 13 is not in contact with the first concave curve or is in contact with a portion 251 of the first concave curve forming, with a straight line dp of the radial plane perpendicular to the axis xa extending from the axis of the cable x to the trailing edge of the hull, an angle γ at least equal to a sliding angle αt. The slip angle is given by the following formula: $$\mathit{\alpha t}=\mathit{arctan}\left(\mathit{Cf}\right)$$

This feature prevents the hull from blocking the cable in the groove when the cable moves laterally in the groove, that is to say parallel to the axis of the pulley. Indeed, if this angular condition is respected, it ensures a sliding of the hull in case of lateral thrust of the cable. In other words, a pulley having a profile as defined with reference to the figure 14 makes it possible to ensure the upturn of the hull from a returned position to an acceptable position.

The first concave curve 25, and therefore the profile of the first groove, is obtained by the skilled person by simulations from this definition.

In practice, for an angle α of the order of 10 °, a first curve forming a curved line having at any point a radius of curvature at least equal to half the length of rope LC of the hull ensures the sliding of the hull in case of lateral thrust of the cable. A curved line is a line devoid of sharp or salient angle (in the mathematical sense of the term). Indeed, if we trace, as visible on the figure 15 , a circle Cr passing through the nose of the hull 14 and the trailing edge BF of the hull 13 whose tangent T at the trailing edge forms an angle at with the line dp, the radius RA of this circle is approximately equal at 55% of the LC rope length of the hull, which is greater than the value of 50% retained above. Advantageously, the dimensions and the shape of the profile first groove are determined so as to make it possible to tilt a reference hull having a maximum length CAR, taken parallel to the rope separating the trailing edge BF from the fairings of the fairing, an LC rope length of the hulls and a maximum thickness E and possibly depending on the coefficient of friction Cf between the reference hull and the pulley. These dimensions and profile are advantageously defined so as to ensure the tilting of the hull from a position returned to an acceptable position without deforming this reference hull.

On the realization of the figure 7 , the width of the first groove lgb is equal to the width of the V lv. Alternatively, the first groove extends beyond the end points. It may comprise the groove of the pulley only or comprise the groove of the pulley and be delimited on either side of the pulley by vertical deflectors or flanges (that is to say perpendicular to the axis of the pulley). pulley) or substantially vertical. The first groove may further be the throat of the pulley which comprises, beyond the V or above the V vertical walls (that is to say perpendicular to the axis of the pulley) or substantially vertical. The walls and flanges as defined make it possible to prevent the cable from leaving the first groove in the event of lateral deflection.

On the realization of the figure 7 , the first groove is the groove 24 of the pulley. Alternatively, the first groove comprises the groove of the pulley. The bottom of the first groove is the bottom of the throat of the pulley. In contrast, the first groove extends beyond the throat of the pulley. It is for example defined at least on one side of the pulley with respect to a plane perpendicular to the axis of the pulley, by a deflector or a flange. The deflector or flange may be fixed relative to the pulley or mobile in rotation relative to the pulley around the axis of the pulley. Advantageously, the first groove comprises lateral edges to limit the lateral movement of the cable. The side edges may extend completely within the portion between the two end points or partially and extend also partially beyond these points.

The pulley, and more precisely the groove of the pulley, has a constant profile. In other words, it is the same in all radial planes of the pulley.

The first curve 25 and the second curve 28 are symmetrical with respect to a plane perpendicular to the axis xp of the pulley and comprising a radius of the pulley passing through the bottom 26. This plane is then the median plane of the groove.

We will now explain more precisely how was obtained the pulley profile according to the invention as shown in FIG. figure 7 . The plaintiff started from the finding that it is necessary to open the V of the figure 6a so that the tail can release on the side during the winding of the cable. On the figure 8a , there is shown a partial section of a pulley 40 according to a second embodiment, in the plane M, which is a plane formed by a side face 18 of the top hull 13a of the segment 12b coming into contact with the pulley. The side face includes the point of the hull entering first in contact with the pulley. The pulley has an open V profile to obtain the turnaround. In this figure, the pulley 40 comprises a V-shaped groove 44. The remarkable hull 13 a bears on a first leg of the V 45 leading edge towards the bottom 46 of the groove 44. The opening of the groove AG is such that that the angle formed between the force action line (represented by the arrow shown in the hull) and the second tab 47 αf is greater than 90 °. In this case, the tail is given a clearance path which allows it to turn in the arrows shown on the figure 8a to adopt the position represented on the figure 8c going through the position shown on the figure 8b following the movement indicated by the arrows by pivoting around the axis of the cable under the action of the cable tension (exerted along the force line of action) when the cable is pulled along the groove. As visible on the figure 8a the direction of the force action line is substantially parallel to the first tab 45. This is why the opening of the V αg in the plane M, which is at least twice the angle αi is substantially equal to αf. Consequently, the opening of the V αg is greater than 90 °. To take account of the friction between the hull tail and the surface of the groove, the limiting opening αg = 2 * αi is at least 95 ° and preferably at least 100 °.

Or, comme visible sur la figure 5, le profil de la gorge de la poulie dans le plan BB est la projection, sur un plan formant un angle β avec le plan M, du profil de la gorge dans le plan M. L'angle β dépend de la longueur CAR qui est la longueur maximale séparant le bord de fuite BF des carènes du carénage de l'axe du câble prise parallèlement à la corde CO de la carène 13a. Il est défini de la manière suivante : $$\mathit{CAR}=R-R\mathit{cos\beta }$$

$$\mathit{CAR}=R\left(1-\mathit{cos\beta }\right)$$

$$\beta =\mathit{arccos}\left(1-\frac{\mathit{CAR}}{R}\right)$$

Il faut donc corriger le V précédemment défini par le biais introduit par l'angle β. L'ouverture αv du V formé par la deuxième courbe 28 dans le plan BB est au moins égale à un angle seuil αs. L'angle seuil αs est donné par la formule suivante : $$\mathit{\alpha s}=\frac{\mathit{\alpha i}}{\mathit{cos\beta }}$$

D'où $$\mathit{\alpha s}=\mathit{\alpha i}\ast \frac{R}{R-\mathit{CAR}}$$

Par conséquent, la largeur du V lv dans le plan BB est au moins égale à la largeur idéale lid donnée par la formule suivante : $$\mathit{lid}=2\left(\mathit{LC}+E\right)\ast \sin \mathit{\alpha s}$$

The angular characteristic is not sufficient to obtain the right turn of the hulls. It is necessary that the width of the groove lgm, in the plane M, be at least equal to a limit width li which is given by the following formula: $$\mathit{li}=2\left(\mathit{LC}+E\right)*\sin \mathit{\alpha i}$$

Now, as visible on the figure 5 , the profile of the groove of the pulley in the plane BB is the projection, on a plane forming an angle β with the plane M, of the profile of the groove in the plane M. The angle β depends on the length CAR which is the maximum length separating the trailing edge BF of the hull of the fairing of the axis of the cable taken parallel to the rope CO of the hull 13a. It is defined as follows: $$\mathit{BECAUSE}=R-R\mathit{cos\beta }$$

$$\mathit{BECAUSE}=R\left(1-\mathit{cos\beta }\right)$$

$$\beta =\mathit{arccos}\left(1-\frac{\mathit{BECAUSE}}{R}\right)$$

It is therefore necessary to correct the V previously defined by the bias introduced by the angle β. The opening αv of the V formed by the second curve 28 in the plane BB is at least equal to a threshold angle αs. The threshold angle αs is given by the following formula: $$\mathit{.alpha.s}=\frac{\mathit{\alpha i}}{\mathit{cos\beta }}$$

From where $$\mathit{.alpha.s}=\mathit{\alpha i}*\frac{R}{R-\mathit{BECAUSE}}$$

Therefore, the width of the V lv in the plane BB is at least equal to the ideal width lid given by the following formula: $$\mathit{lid}=2\left(\mathit{LC}+E\right)*\sin \mathit{.alpha.s}$$

The first curve 25 delimiting the first groove 24 has at least from the first end point 33 to the second end point 34 a concave shape.

It may have at least from the first extremal point 33 to the second extreme point 34 a shape of V or have several sharp sharp corners AS as shown in the drawings. Figures 9a and 9b . In other words, the curve forms a substantially broken line. In these figures, the curves have a sharp or salient angle at the bottom 26 and are symmetrical with respect to the plane perpendicular to the axis of the pulley and comprising a radius of the pulley. These profiles are more efficient for ensuring the upturn of the hulls than the V profile. These profiles are advantageously, but not necessarily symmetrical with respect to a plane perpendicular to the axis of the pulley passing through the bottom 26. In a variant, the first curve has sharp or salient angles and has a tangent substantially parallel to the axis of the pulley xp at the bottom. The bottom is then the point of the curve located on the median plane of the throat.

Advantageously, as shown on the figure 7 the first curve 25 is, between the end points 33, 34, a curved line. In other words, it is a concave curve devoid of sharp or salient angle (in the mathematical sense of the term). In other words, the curve substantially never comprises more than one tangent at the same point. Its derivative is substantially continuous.

When the first groove (or first curve) has a V-shaped section (first V-shaped curve), it must have a width at least equal to lid so that the reversal is guaranteed. When the first groove (or first curve) has a section such that the first curve is U, then it may have a width of up to 0.7 * lid because it has no sharp angles in which the tail of the hull can get stuck. In this case, the opening of the V can also be lower than the threshold angle. In other words, the V must have a width at least equal to 0.7 * lid. On the other hand, turning can be more difficult than when the V has a width at least equal to lid. Below this threshold, it is not certain that the reversal takes place.

Advantageously, in the case of a first groove having a U-shaped profile, the first groove is at the bottom of the bath. The throat in the background tub has the advantage of ensuring a certain and fluid reorientation of the hull and allows to orient the hull in a substantially lying down position in the bottom of the groove.

• une courbe supérieure SUP présentant un premier rayon de courbure R1 égal à ½* g*lid passant par le fond et dont le centre est situé sur une droite perpendiculaire à l'axe de la poulie passant par le fond,
• une courbe inférieure INF comprenant une portion centrale CENT s'étendant sensiblement parallèlement à l'axe de la poulie symétrique par rapport à un plan perpendiculaire au plan radial passant par le fond et s'étendant, le long de l'axe de la poulie sur une première largeur égale à ½*g*lid et comprenant, de part et d'autre de la portion centrale CENT, des portions latérales LAT1 et LAT2 reliant la portion centrale aux points extrêmes 133, 134 et présentant un deuxième rayon de courbure R2 égal à 1/4*g*lid. Chaque portion latérale s'étend sur une largeur égale à ¼*g*lid selon l'axe de la poulie. Les centres des portions latérales sont symétriques l'une de l'autre par rapport au plan vertical PV passant par le fond et perpendiculaire à l'axe de la poulie xp

This means that the first curve has a central zone, this central zone has a width equal to g * lid where lid is the ideal width and g is between 0, 7 and 1, between the extreme points coinciding with the extreme points of a reference curve in V 128 having a width equal to g * lid. The central zone is delimited by the two curves (see shaded area) 10:

• an upper curve SUP having a first radius of curvature R1 equal to ½ * g * lid passing through the bottom and whose center is situated on a straight line perpendicular to the axis of the pulley passing through the bottom,
• a lower curve INF comprising a central portion CENT extending substantially parallel to the axis of the pulley symmetrical with respect to a plane perpendicular to the radial plane passing through the bottom and extending along the axis of the pulley on a first width equal to ½ * g * lid and comprising, on either side of the central portion CENT, side portions LAT1 and LAT2 connecting the central portion to the end points 133, 134 and having a second radius of curvature R2 equal at 1/4 * g * lid. Each lateral portion extends over a width equal to ¼ * g * lid along the axis of the pulley. The centers of the lateral portions are symmetrical to one another with respect to the vertical plane PV passing through the bottom and perpendicular to the axis of the pulley xp

The central area can be one of two curves. The lower curve is the preferred embodiment of the invention.

Advantageously, the central zone of the first curve is formed by a pulley having a groove whose width is the width of the central zone.

Advantageously, the first curve comprises upper portions extending substantially perpendicularly above the end points of the V so as to prevent the cable from leaving the first groove during a vertical deflection of the cable. These flasks are attached to the pulley or belong to the pulley or are fixed with respect to the axis of the pulley.

The first curves between the upper curve and the lower curve have the advantage of checking the angular condition to prevent the hull prevents the lateral movement of the cable.

On the Figures 11a to 11c in successive planes parallel to the plane M, successive directions adopted by the lateral face of the reference hull comprising the first point to come into contact with the pulley have been represented, when the cable is wound up. The hull 13a arrives trailing edge down ( figure 11a in the plane M) and when pulling the cable, it pivots around the axis of the cable (see figure 11b ), under the effect of the tension of the cable, until reaching the substantially flat position in which the leading edge is turned towards the bottom of the groove and the trailing edge is turned towards the outside of the throat ( figure 11c ). This profile facilitates and simplifies the tilting of a hull because the flattened central portion of the groove of the pulley involves a significant distance between the axis of reaction of the throat of the pulley on the hull (axis from the edge leak towards the center of the portion of circle formed by the central portion) and the axis of rotation of the hull (extending along the trailing edge axis - towards the axis of the channel xc or axis of the cable x) because of the large distance between the axis of the cable and the center of the portion of circle formed by the central portion. This profile also allows the cable and its fairing which have placed substantially flat to come safely rest on the sides of the pulley when the cable is stressed laterally (that is to say, parallel to the axis of the pulley) in the event of a turn of the ship for example. If the cable and the leading edge of the fairing are positioned on the right side, they stay there. If they are on the wrong side, the profile of the pulley allows a near smooth reversal that allows the cable (where the efforts sit) to come to rest against the side of the pulley. This slip is present but less fluid in the other pulley configurations.

In summary, the pulley according to the invention and more generally the guide device according to the invention makes it possible to ensure the recovery of a hull coming to bear on the pulley with a trailing edge orientation towards the bottom of the groove of the pulley and leading edge vertically from the trailing edge. The hull brings with it the keels it is linked to rotation around the cable, that is to say the hulls of the same section. The pulley according to the invention also makes it possible to straighten the hulls of a cable organized in a single section in which the hulls are all connected to each other around the cable in the event of breakage of an inter-hull connection for example under the effect of a double twist which ensures a passage of the faired cable in the pulley without deformation of the hulls. It also makes it possible to straighten the top hull of a fairing comprising a single section extending over a length less than the length of the cable from the end intended to be immersed. It also makes it possible to straighten hulls of a ducted cable comprising hulls which are all free to rotate around the cable relative to each other. It furthermore makes it possible, by virtue of its width, to guide a cable organized in a single section presenting a residual torsion (very close submerged torsion that is not resorbed at the passage of the pulley) without deforming the hulls, which is not not possible with a narrow V-pulley.

The guiding device according to the invention is efficient and simple because it does not require the installation of a cable follower device (that is to say, able to follow the cable when it moves laterally and vertically with respect to pulley).

The pulley according to the invention, and more generally the guide device according to the invention, by its profile, does not ensure a reversal of the hull to a situation in which the trailing edge is located in the vertical of the leading edge. For example, in the case of the pulley at the bottom of the tub, the hull is returned to a position in which it is substantially flat (trailing edge slightly raised upwards). It must rotate about ¼ turn against ½ turn (if it had to adopt the trailing edge position above and above the leading edge) which facilitates the operation of recovery of the hull by the pulley .

Advantageously, the guide device comprises, between the winch and the pulley, a straightening device for orienting the hulls that leave the pulley towards the winch about the axis of the cable so that they have a predetermined orientation relative to the winch drum, for example leading edge down and trailing edge vertically to the leading edge. These devices are only really effective when the cable position is perfectly known (and this is the case at the exit of the pulley).

On the realization of Figures 4a and 4b , the hulls of the sections have a constant section, that is to say fixed, along the leading edge. By section is meant the profile of the hull in a transverse plane, that is to say a plane extending perpendicular to the leading edge BA, that is to say the axis of the channel xc. By constant section is meant a section having substantially the same shape and dimensions in all transverse planes, whatever their positions along the leading edge between the side faces 17, 18. In other words, the trailing edge BF is substantially parallel to the leading edge BA over the entire width l of the hull. The width 1 of the hull is the distance between the two lateral faces 17, 18 along an axis parallel to the leading edge BA.

The trailing edge BF constitutes a bearing edge parallel to the leading edge BA.

Alternatively, as visible on the Figures 12a to 12c at least one hull 130 of the fairing is a beveled hull. A beveled hull is a hull which comprises a bearing edge BAPa comprising a first abutment edge Bza with respect to the leading edge BAa, the bevel being made so that the distance between the leading edge BAa and the first Bza bevel edge, taken along an axis perpendicular to the leading edge BAa and the xc axis of the channel 16 varies linearly along the xc axis. By first Bza bevel edge is meant a first Bza abutment edge which extends longitudinally substantially along a line which is at an angle or inclined with respect to the leading edge BAa. The first bearing edge Bza extending longitudinally in a first plane containing a plane or parallel to a plane defined by the leading edge BAa and the rope CO of the hull. In other words, the first support edge Bza is at an angle with respect to the leading edge BAa in this first plane.

The bearing edge BAPa extends longitudinally between two ends E1 and E2. The support edge BAPa is arranged such that the distance between the support edge BAPa and the leading edge BAa decreases continuously from a first end E1 of the first Bza support edge to a first lateral face 180. from the hull closer to the second end of the first support edge Bza than the first end of the support edge, along an axis parallel to the leading edge BA.

On the realization of the figure 12b , this side face 180 is the lateral face of the hull 130 a furthest from the free end 6 of the cable (visible on the figure 2 ) in the opposite direction of the arrow. The other side face 170 is the lateral face of the hull 130a closest to the free end 6 of the cable. This feature facilitates the overturning of the hull 130 when it comes to bear against the pulley by its trailing edge, during the winding of the cable, that is to say when pulling the cable relative to the axis of the pulley xp according to the arrow f. Indeed, on the figure 12b , the position P 'is represented on the pulley 4 of the figure 7 from the point where the hull 130a comes into contact with the pulley 4 due to the traction of the cable with respect to the axis of the pulley xp in the direction of the arrow. This point is located at a distance B '(represented on the figure 12b ) of the cable 1 perpendicular to the axis of the cable x. The position P, on the pulley 4, of the point where a hull 13 which would have had the shape represented on the Figures 4a and 4b would have come into contact with the pulley P. This point is located at a distance dB of the cable 1 perpendicular to the axis of the cable x. The distance dB 'is less than the distance dB, therefore, the upturn of the hull is facilitated and therefore the upturn of the hulls of the section is also facilitated. This is valid in the case of the pulley of the invention but also in the case of any guide device, in particular of the type for modifying the orientation of the hull relative to the guide device by rotation of the hull around the axis of the cable. In particular, the beveled support edge makes it possible to facilitate the reorientation of a hull in any guide device making it possible to modify the orientation of the hull with respect to the guide device by rotation of the hull around the axis of the hull. cable (or channel) when the hull bears on a bearing surface of the guide device by the support edge. In other words, the beveled abutment edge facilitates in particular the reorientation of the hull by any guide device comprising a surface opposing the traction of the streamlined cable during winding or during unwinding of the cable. The invention operates for example with guiding devices to track the cable in case of lateral and / or vertical movement of the cable. In general, the presence of a beveled hull makes it possible to limit the risks deterioration of the fairing, especially in the presence of a double twist by facilitating the tilting of a hull at its entry into a guiding device, which limits the risk that the fairing does not get stuck in the guiding device.

This embodiment also has an advantage in the case of a pulley having a constant profile, and more particularly a pulley according to the invention. Indeed, the point of contact P 'is situated in a plane M' situated at a distance D 'which is smaller than the distance D at which the plane M (including the point P) is situated, with respect to the axis of the pulley, parallel to the axis of the cable x. Consequently, the groove of the pulley is shallower in the plane M 'than in the plane M. Indeed, the profile of the groove in the plane M (or M') is the projection of the profile of the groove in a plane radial passing through the plane P (or respectively P ') on the plane M (or respectively M') forming an angle β (or respectively β 'less than β) with the radial plane at the point considered. However, the fact that the groove is shallower in the plane M 'than in the plane M implies that the pulley is flatter in the plane M than in the plane M' at least at the bottom (ie say at the central portion of the curve defining the groove). If the hull comes into contact on the central portion of the pulley at the bottom of the bath, the central portion is flatter in the plane M 'than in the plane M, in other words, the radius of the contact surface at the point P is more important in the plane M 'in the plane M, which facilitates the tilting of the hull under the effect of the traction of the cable relative to the axis of the pulley.

On the realization of the figure 12b , the tapered hull comprising the bevel is the hull 130a head section, that is to say the hull farthest from the end of the cable to be immersed. This facilitates the tilting of the hull 130a during the winding of the cable and to facilitate the tilting of the entire section 120 because the hull, being connected to rotation around the cable to the other hulls of the section, it drives all the hulls of the section 120 in its movement around the cable. The leading hull 130a is a hull which is adjacent to a single other hull 130b belonging to the same section 120. The first Bza abutment edge of the head hull 130a is arranged so that the distance between the leading edge BA and the first Bza bevel edge is continuously decreasing, along an axis parallel to the leading edge BAa, from a first end E1 of the first Bza support edge to a second end E2 of the first Bza support edge further from the other hull 130b than the first end E1 along the axis parallel to the leading edge BAa.

Alternatively, the tapered hull is the tail hull of the section, that is to say the hull closest to the end of the cable to be immersed. This facilitates tilting of the hull during unwinding of the cable (when the hull bears against the pulley on the other side of the pulley with respect to the axis of the pulley) and to facilitate the tilting of the entire section because the hull (by propagation of the rotational movement on the whole section). The tail hull is a hull that is adjacent to a single hull of the same section. The first abutment edge is configured such that the distance between the leading edge BAa and the first beveled abutment edge decreases along the leading edge BAa from a first end of the first abutment edge facing the other hull to a second end of the first support edge further from the other hull than the first end, along the axis parallel to BAa. The other end of the first support edge is closer to a lateral face than the first end of the support edge. This embodiment, like the previous one, makes it possible to ensure the tilting of all the hulls of the fairing sections, without having to provide only hulls skived over the entire fairing, which would have the effect of limiting the performance of the fairing in terms of drag reduction.

The other hulls are not beveled hulls. They do not include a first abutment edge. The support edge is the trailing edge and is substantially parallel to the leading edge over its entire length.

Advantageously, each section comprises at least one end hull (head or tail) comprising a beveled edge.

In a variant, a fairing comprising a single section as defined above may comprise a hull with a beveled support edge. This section extends for example over a length less than the length of the cable from the end intended to be immersed. In this case, the leading hull of the section is advantageously a hull comprising a beveled support edge arranged as for the above-described head hull.

In another variant, the section extends over the entire length of the cable.

In all fairing configurations (of the type comprising a section, several sections or including hulls all free to rotate relative to each other around the elongated element), all the hulls could be beveled hulls. This would facilitate the tilting of each hull in case of breakage of inter-hull link downstream of the hull seen from the pulley, when hulls are initially linked. In the case where the hulls are free to rotate relative to each other, it facilitates the tilting of each hull on arrival on a guidance device More generally, the tapered hull avoids having to to link the hulls to each other and thus makes it possible to limit the costs of the fairing and the assembly time of the fairing.

If it is desired to facilitate the reorientation of the hulls in the event of winding of the cable, the bevel is made such that the distance between the leading edge BA and the first beveled abutment edge decreases, along the axis xc from the end of the first abutment edge closest to the end of the cable intended to be immersed to the end of the abutment edge opposite the end of the cable intended to be immersed and vice versa if wishes to facilitate the tilting during the unwinding of the cable.

On the realization of Figures 12a and 12b , the bearing edge BAPa is the trailing edge BF. It comprises the first Bza beveled support edge and a second support edge Bla which extends parallel to the x axis and is located at a fixed distance from the leading edge along the x axis. The first beveled abutment edge is connected to the side face 180 and the second abutment edge Bla, in the direction of the leading edge by rounded connection or chamfers. The maximum chord length LC is the distance between this second bearing edge Bla and the leading edge. In a variant, the bearing edge does not have a second bearing edge Bla extending parallel to the x axis. The bevel extends substantially over the entire width of the hull and is advantageously, but not necessarily, connected to the side faces by fillets or chamfers.

As visible on Figure 12c and 12d representing sections of the hull in respective planes N and Q, represented figure 12a , parallel to the leading edge and perpendicular to the side faces 170, 180, the hull comprises a first thick portion 130a1 visible on the figure 12c and a second thin portion 130a2 having a second thickness less than the first thickness e1 of the thick portion. The second thickness e2 is substantially equal to the thickness of the end of the tail 15 opposite the end of the tail connected to the nose 14 of the hull. The first edge comprises a first portion Bza1 extending in the first thick portion 130a1 of the hull and a second portion Bza2 extending into the thin portion. The first portion of the first bearing edge Bza1 is connected to the longitudinal faces 122, 123 by respective chamfers 132, 133 respectively. In other words, the hull comprises chamfers connecting the first portion of the first bearing edge Bza1 to the respective longitudinal faces 122, 123. This makes it possible to thin the trailing edge in the thick part of the hull and thus to limit the risk of the hull jamming on the guiding device. Alternatively, the chamfers extend over the entire length of the first support edge.

Alternatively, the first portion of the leading edge Bza1 is connected to the side faces by respective bulge surfaces. By bulged surfaces is meant curved convex surfaces. This embodiment also makes it possible to limit the thickness of the support edge. In a variant, the curved surfaces extend over the entire length of the first support edge. The chamfers and curved surfaces are two non-limiting technical solutions to obtain the characteristic that at least a first portion of the first support edge Bza1 has a thickness e3 less than the thickness of the hull in any longitudinal plane parallel to the edge and perpendicular to the side faces of the hull intersecting the first portion of the first support edge Bza1. The thickness of the hull in a section plane is the distance separating the first longitudinal face 122 of the second longitudinal face 123 in a direction perpendicular to the rope CO in the plane of section of the hull. Advantageously, the first portion Bza1 has the same thickness as the second bearing edge Bla which extends parallel to the x-axis and is located at a fixed distance from the leading edge along the x-axis.

We will now describe a support edge of a hull according to a second embodiment of the invention with reference to the figure 13 . All that has been said about the implementation of the hull on a fairing, the configuration of the fairing, the thickness of the support edge and the arrangement between the first support edge and the second support edge remains valid.

On the figure 13 , the bearing edge BAPb connects the two lateral faces 270, 280. The hull 230 is formed of two parts 231, 232 contiguous along the first beveled abutment edge Bzb. The hull is configured to be held in an expanded configuration (visible on the figure 13 ), when subjected to the hydrodynamic flow of water, in which the two parts 231, 232 are disposed relative to each other around the first support edge, so that the hull has a trailing edge parallel to the leading edge and a constant section along the leading edge. In other words, the string length is constant. The hull is held in the deployed position as long as the relative pivoting torque between the two parts about an axis formed by the first bearing edge Bzb is less than or equal to a predetermined threshold. The longitudinal direction of the first support edge is the direction of the axis formed by the bearing edge. The threshold is greater than the torque that can be exerted by the hydrodynamic flow of water on the hull when the hull is immersed and possibly towed along the trailing edge axis, leading edge. The hull is also configured to allow relative pivoting between the two parts 231, 232 around the first bearing edge Bzb (see the arrow), when a relative pivoting torque between the two parts 231, 232, applied around the axis formed by the first bearing edge Bzb exceeds the threshold so that the end hull passes from the deployed configuration to a folded configuration around the support edge. The axis formed by the first bearing edge is an axis contained in the first bearing edge and parallel to the longitudinal axis of the first bearing edge. In the folded configuration the hull does not have a constant section and the trailing edge is not parallel to the leading edge over its entire length. In the folded position, the hull is folded along the first support edge Bzb. In the deployed position, the hull is unfolded. This embodiment makes it possible to limit or avoid performance reductions in terms of drag reduction. hydrodynamics of the hull while facilitating the progression of the hull in the pulley and its reversal.

The first part 231 extends on one side of the first bearing edge delimited by the first bearing edge Bzb, the second bearing edge (if it exists) Blb, the leading edge BA, one face 280 and the portion of the other side face 270 extending between the leading edge BA and the first bearing edge Bzb.

The second part 232 is delimited by the first bearing edge Bzb, the part of the first lateral face 270 extending from Bzb to the trailing edge BF and the part of the trailing edge BF located between Bzb and the first face lateral 270.

The first part 231 is for example made of rigid material and the second part 232 is made of flexible or flexible material which does not substantially deform when the relative pivoting torque between the two parts around the first bearing edge is less than or equal to at the threshold and which bends when the torque exceeds the threshold, in particular when the point of intersection between the trailing edge and the first lateral face 270 comes into abutment against a guiding device. The second part may, for example, be made of polyurethane. The first part can be made of polyurethane with a rigidity greater than that of the second part or in POM or PET. Alternatively, the two parts have a rigidity such that they do not deform under the effect of a torque greater than the threshold but are connected by a pivot connection around the first support edge and the hull comprises a stabilizing device configured to maintain the two parts in the relative position deployed when the relative pivoting torque is less than or equal to the threshold and so as to allow rotation between the two parts so that they pass into the relative position folded around the first edge 'support when the couple exceed the threshold. The coupling device is for example a device comprising a fuse or a compression spring.

Advantageously, at least one beveled hull or each beveled hull is dimensioned so as to be more resistant to a pressure force, applied in a direction perpendicular to the leading edge connecting the leading edge to the trailing edge, than the other hulls of the section in question (which are not bevelled), or more general than other non-beveled hulls. This feature makes it possible to limit the risk of deformation and breakage of the hulls when they engage in the guiding device, turn around and cross this guiding device. For this purpose, this hull is for example made of a material harder than the other hulls and / or it comprises ribs providing this additional reinforcement. Advantageously, the fairing comprises at least one stepped end hull reinforced and cooperating with the immobilizer. This makes it possible to reduce the costs and possibly the weight of the fairing because only one or the beveled hulls differ from the others, all the others being identical.

The invention also relates to an assembly comprising a ship, the towing assembly being embarked aboard the ship. The vessel is intended to move at a nominal speed by a nominal sea state. The towing package is installed on the vessel so that the towing point is at a nominal height.

Claims (17)

1. A towing assembly comprising an elongate element faired by means of a fairing comprising a plurality of fairing elements (13), the fairing elements comprising a canal (16) intended to accept the elongate object and being profiled in such a way as to reduce the hydrodynamic drag of the elongate object which is at least partially immersed, said fairing elements (13) being pivot-mounted on the elongate element around the longitudinal axis of the canal (16), the towing assembly further comprising a towing and handling device intended to tow the faired elongate element while the latter is partially immersed, the towing device comprising a winch (5) allowing the faired elongate element (1) to be wound in and paid out through a guide device (4) that allows the elongate element (1) to be guided,
   characterized in that the guide device comprises a first groove (24) the bottom (26) of which is formed by the bottom of the groove of a pulley (4), the first groove (24) being delimited by a first surface (25) having a profile that is concave in a radial plane of the pulley, the width of the first groove and the curvature of the profile of the first curved surface in the radial plane being determined in such a way as to allow the fairing element, under the effect of the rotation of the fairing element about the axis of the elongate element x under the effect of the traction of the elongate element with respect to the guide device along the longitudinal axis thereof, to flip from a turned-over position in which the fairing element is oriented with its trailing edge toward the bottom of the first groove into an acceptable position in which it is oriented with the leading edge toward the bottom of the first groove.
2. The towing assembly as claimed in the preceding claim, in which the guide device comprises a first groove (24) the bottom of which is formed by the bottom (26) of the groove of a pulley (4), the first groove (24) being delimited by a first concave surface of which the cross section in a radial plane of the pulley is a first concave curve (25) comprising the bottom (26) coinciding with the bottom of a second, reference, groove (29) delimited by a second curved surface of which the cross section in the radial plane BB is a V-shaped reference curve (28), the aperture of the V being at least equal to twice a threshold angle αs, and the width of the V lv, measured along a straight line d parallel to the axis of the pulley, is at least equal to a threshold width Is, given by: $$\mathit{ls}=\mathrm{0,7}\ast \mathit{lid}$$

   

   $$\mathit{lid}=2\left(\mathit{LC}+E\right)\ast \sin \left(\mathit{\alpha s}\right)$$

   

   $$\mathit{\alpha s}=\mathit{\alpha i}\ast \frac{R}{R-\mathit{CAR}}$$

   

   where αi is a limit angle greater than 45° and less than 90°, where R is the radius of the pulley and where CAR is the maximum distance separating the trailing edge BF of the fairing elements of the fairing from the axis of the elongate element, measured parallel to the chord CO of the fairing elements, where LC is the chord length of the fairing elements and E is the maximum thickness of the fairing elements,

   in which the first curve (25) is coincident with the second curve (28) at two endpoints (33, 34) of the reference curve (28), the first curve (25) is at every point comprised between each of the endpoints (33, 34) and the bottom (26) coincident with the second curve (28) or closer to the axis of the pulley (xp) than the second curve (28) along the radius of the pulley in the radial plane BB.
3. The towing assembly as claimed in the preceding claim, in which the limit angle αi is given by the following formula: $$\mathit{\alpha i}=\frac{\pi }{4}+\frac{1}{2}\mathit{Arctan}\left(\mathit{Cf}\right)$$

   

   where Cf is the coefficient of friction between the material that forms the exterior part of the tail of the fairing element and the material that forms the surface delimiting the groove of the pulley.
4. The towing assembly as claimed in any one of the preceding claims, in which the first groove is the groove of the pulley.
5. The towing assembly as claimed in any one of the preceding claims, in which the concave first curve (25) has a U-shaped profile between the endpoints.
6. The towing assembly as claimed in any one of the preceding claims, in which the fairing elements comprise a fairing element comprising a nose (14) accepting the elongate element and comprising a leading edge (BA) and a tail (15) of streamlined shape extending from the nose (14) and comprising a trailing edge (BF), the cross section of the first surface in the radial plane of the pulley being a first concave curve, the concave first curve being defined in a radial plane (BB) of the pulley such that, when the fairing element extends with the leading edge (BA) perpendicular to the radial plane (BB), whatever the position of a fairing element in the first groove (24), when the nose (14) of the fairing element (13) is bearing on the concave first curve and the elongate element (1) is exerting on the fairing element (13), in the radial plane, a force to press the nose (14) of the fairing element (13) against the pulley, said pressing force Fp comprising a component CP perpendicular to the axis of the pulley and a lateral component CL, the trailing edge (BF) of the fairing element (13) is not in contact with the concave first curve or is in contact with a part (251) of the concave first curve that forms, with a straight line dp of the radial plane perpendicular to the axis xa extending from the axis of the elongate element x as far as the trailing edge of the fairing element, an angle γ that is at least equal to an angle of slip αt. The angle of slip is given by the following formula: $$\mathrm{\alpha }\mathrm{t}=\mathrm{Arctan}\left(\mathrm{Cf}\right)$$

   

   where Cf is the coefficient of friction between the material that forms the exterior part of the tail of the fairing element and the material that forms the surface delimiting the groove of the pulley.
7. The towing assembly as claimed in any one of the preceding claims, in which the first curve has a U-shaped profile and has a central zone of width equal to g*lid, where lid is the ideal width and g is comprised between 0.7 and 1, between the endpoints coinciding with the endpoints of the reference curve having a width equal to g*lid, the central zone being delimited by the following two curves:

   - an upper curve having a first radius of curvature R1 radius equal to ½* g*lid passing through the bottom and the center of which is situated on a straight line perpendicular to the axis of the pulley passing through the bottom,

   - a lower curve INF comprising a central portion CENT extending substantially parallel to the axis of the pulley symmetric with respect to a plane perpendicular to the radial plane passing through the bottom and extending, along the axis of the pulley, over a first width equal to g*lid and comprising, on each side of the central portion CENT, lateral portions LAT1 and LAT2 connecting the central portion to the endpoints 133, 134 and having a second radius of curvature R2 equal to 1/4*g*lid.
8. The towing assembly as claimed in any one of the preceding claims, in which the the fairing elements are rigid.
9. The towing assembly as claimed in any one of the preceding claims, in which the fairing comprises a plurality of fairing portions (12), each fairing portion (12) comprising a plurality of fairing elements (13) joined together along the axis of the elongate element and articulated to one another, the fairing portions (12) being free to rotate about the axis of the elongate element relative to one another.
10. The towing assembly as claimed in the preceding claim, in which the fairing portions have respective heights along the axis of the canal, these heights being defined as a function of the angular stiffnesses k of the respective fairing portions, and as a function of the chord length LC of said fairing elements of said respective portions so as to prevent a full twist from forming on said respective portions.
11. The towing assembly as claimed in the preceding claim, in which the fairing portions have respective heights that are less than a maximum height hmax such that: $$\mathit{hmax}\le \frac{\pi \ast k}{F{\mathit{LC}}^2}$$

    

    where F is a constant comprised between 250 and 500.
12. The towing assembly as claimed in any one of the preceding claims, in which at least one fairing element comprises a leading edge (BAa) and a trailing edge (BAPa), comprises a bearing edge comprising a first bearing edge (Bza) that is mitered with respect to the leading edge (BA), the first bearing edge (Bza) being arranged in such a way that the distance between the leading edge (BAa) and the bearing edge (BAPa), measured perpendicular to the leading edge (BAa), decreases continuously, along an axis parallel to the leading edge (BAa), from a first end (E1) of the first bearing edge (Bza) to a second end of the first bearing edge (E2), said fairing element being referred to as a mitered fairing element.
13. The towing assembly as claimed in the preceding claim, in which the bearing edge is arranged in such a way that the distance between the bearing edge (BAPa) and the leading edge (BAa) decreases continuously, along an axis parallel to the leading edge (BAa), from the first end (E1) of the first bearing edge (Bza) to a first lateral face (180) of the fairing element closer to the second end of the first bearing edge (Bza) than to the first end of the first bearing edge.
14. The towing assembly as claimed in either one of claims 12 and 13, in which the bearing edge is the trailing edge.
15. The towing assembly as claimed in any one of claims 12 to 14, in which the mitered fairing element is sized in such a way as to be more resistant to a pressure loading, applied in a direction perpendicular to the leading edge and connecting the leading edge to the trailing edge, than the other fairing elements.
16. The towing assembly as claimed in any one of claims 12 to 15, in which the mitered fairing element comprises two parts (231, 232) back to back along the first bearing edge (Bzb), the fairing element being configured to be kept in a deployed configuration when subjected to the hydrodynamic flow of the water, the two parts (231, 232) being arranged, relative to one another about the first bearing edge (Bzb), in such a way that the fairing element has a trailing edge parallel to the leading edge (BA) and a cross section that is constant along the leading edge, and configured in such a way as to allow relative pivoting between the two parts (231, 232) about the first bearing edge (Bzb) when a torque inducing relative pivoting between the two parts (231, 232), applied about an axis formed by the first bearing edge (Bzb), exceeds a predetermined threshold so that the fairing element passes from the deployed configuration into a configuration folded about the bearing edge.
17. The towing assembly as claimed in any one of claims 12 to 15, insofar as they are dependent on claim 9, in which, of said portions, at least one comprises at least one end fairing element, adjacent to one single other fairing element belonging to said portion, having a bearing edge comprising a first bearing edge (Bza) which is mitered with respect to the leading edge (BA), the first bearing edge (Bza) being arranged in such a way that the distance between the leading edge (BA) and the first bearing edge (Bza), considered perpendicular to the leading edge (BA), decreases continuously, along an axis parallel to the leading edge, from a first end (E1) of the first bearing edge (Bza) to a second end (E2) of the first bearing edge (Bza), further away from the other fairing element (130b) than the first end (E1), along the axis parallel to the leading edge.

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