EP3261913B1 - Fairing, elongate faired element and towing assembly - Google Patents

Description

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

The document JP S61 113093 U constitutes an example of the prior art disclosing an elongated fairing element.

The context of the invention is that of a naval vessel or ship intended to tow a submersible object such as a variable immersion sonar integrated in a towed body. In such a context, in the non-operational phase, the submersible body is stored on board the ship and the cable is wound around the reel of a winch making it possible to wind and unwind the cable, that is to say to deploy and to recover the cable. Conversely in the operational phase, the submersible body is immersed behind the ship and towed by the latter using the cable, the end of which is connected to the submersible body. The cable is wound / unwound by the winch through a cable guiding device which allows the cable to be guided.

To obtain strong immersion at high towing speeds, the towing cable is streamlined, which reduces its hydrodynamic drag as well as the vibrations generated by the hydrodynamic flow around the cable. The cable is coated with a segmented fairing composed of rigid hulls having shapes intended 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 the water and towed by the ship. The rigidity of the hulls is necessary for large immersions going hand in hand with high towing speeds of at least 20 knots. Flexible fairings are only useful for economically profiling chains or cables of buoys subjected to sea 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 into hulls is necessary so that the cable can pass through guide elements of the pulley type, and so as to be able to withstand a lateral movement of the cable in the event of a change of course of the ship and so as to be able to be wound on the reel of a winch.

In normal operating condition, the hulls are mounted mobile in rotation around the longitudinal axis of the cable. It is indeed necessary that the hulls can rotate freely around the cable in order to be correctly oriented with respect to the flow of water. Each hull is however linked to its two neighbors axially and in rotation about the cable so as to be able to pivot relative to them about an axis parallel to the x axis by a small maximum angle of the order of a few degrees. This inter-hull link allows in particular the fairing assembly to be able to pass smoothly through all of the guide elements. Consequently, the rotation of a hull causes a rotation of its neighbors and gradually that of all of the hulls. Consequently, both when the cable is deployed in water and when it is wound around the reel, any change in orientation of one of the hulls, gradually affects all the hulls careening the cable. When the cable is deployed at sea, the hulls naturally orient in the direction of the current generated by the movement of the vessel. Similarly, the guide device is conventionally configured to orient and guide the hulls which pass through it so that they have a predefined orientation relative to the winch reel, all the hulls adopt the same cable as the cable is raised. orientation relative to the reel, orientation which makes it possible to wind the cable while keeping the scales parallel to each other in turn.

However, the Applicant has found that, when the shrouded cable is wound around the reel of a winch in order to recover the towed body, it occasionally happens that the shroud is badly deteriorated or even crushed when it passes through the devices. guidance, which can make the entire sonar system unavailable. It may even happen that this deteriorates the guide device. For example, some variable immersion sonar systems installed on certain ships and operated in the normal way by military crews encounter problems with hull grinding 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 thus lead to the unavailability of the entire towing system and, consequently, of the sonar.

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

To this end, the Applicant has first of all, within the framework of the present invention, identified and studied the cause of this problem of grinding of the hulls by observation of the faired cable in operational situation and by modeling of the faired cable in operational situation and different forces acting on it, in particular hydrodynamic and aerodynamic flows as well as gravity.

During the operational phase, the streamlined cable is towed by the ship and has a submerged end. Very often, the tow point is a point on a pulley that is at a certain height above the water. By towing point of a cable or of a fairing, is meant 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 of the fairing respectively. . When the ship is moving, under the action of drag, the cable moves away from the transom to disappear underwater a little further than vertical from the towing point. The length of the faired 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 in abutment on the pulley or in abutment on a guidance device on board the ship , is oriented correctly in the direction of the flow although it is well above in the air (Leading edge facing the flow and trailing edge trailing. The first hull in the water (it is ie the hull just submerged) is supposed to take a correct orientation in the flow coming from the speed of the ship (Leading edge facing the flow and trailing edge trailing) .But between these two remarkable hulls, the column fairing may bend since it is in the air just subject to vibrations, insignificant air flow and gravity. Under the effect of the stresses of the sea, towing conditions and waves, situations of torsion of this aerial column are regularly observed. The first cau getting twisted is caused by gravity as soon as the cable has moved away from the vertical, which necessarily happens to it 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 to one side (in the air) and then will straighten (in the water). This is the nominal situation of the fairing column. This twist is a function of the intrinsic stiffness of the fairing column but also of the air length. A situation in which the aerial part of the fairing 2 is slightly twisted, that is to say in torsion around the axis of the cable is shown on the figure 1A . On the figure 1A , the vertical direction in the terrestrial frame of reference is represented by the z axis and the orientation of the section of certain hulls is shown in the zones A, B and C delimited by dotted lines. In the situation represented on the figure 1A , the last hull 3 in engagement with the ship is oriented vertically (trailing edge up) 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 which are in the water are straightened under the action of the water flow acting according to the arrow FO as that is represented in zone C (trailing and leading 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).

It happens from time to time that, depending on the sea conditions, packets of water or breaking waves more or less fall towards the transom of the ship while creating in the aerial part of the cable a flow momentarily opposite to that which reigns lower and which corresponds to the forward speed of the ship. These bodies of water are perfectly capable of further twisting 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 makes, in its aerial part, a half-turn around the cable. This means that two hulls on the aerial part of the fairing column have trailing edges forming an angle of 180 degrees around the cable. The part of the fairing situated between these two hulls is twisted or twisted. From this situation, it can happen that these parts of fairings which are therefore upside down compared to the average flow given by the speed of the ship, are then found suddenly bathed again by this average flow (because of the movement of the ship, that of the vases etc.) the fairing part upside down is therefore requested to return in the right direction (linked to the normal average flow). She can then:

• cancel its U-turn and return to its initial position by describing the reverse rotation from that which had brought it backwards. It is then correctly oriented.
• or add to the existing half-turn another half-turn which brings it back to the correct orientation in the flow but which has the consequence of twisting the aerial part of the fairing above it by 1 turn (or 360 °) and to twist in the same way a portion below it by one turn (or 360 ° but this time in the other direction). The part which was initially upside down returned to the correct orientation in the average flow related to the speed of the ship but there therefore occurred two twists of a turn one above in the air and l other below in the water. We speak of complete twisting of the fairing (which can be translated by twist in English terminology). This complete twist is a stable situation of the fairing column or the 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 makes a full revolution in the direction of arrow F1 around the cable. The fairing column 2 crosses the surface S and remains correctly oriented over a certain length L of the order of a few meters or less sometimes. Then the fairing column 2 makes a full 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 complete double twist around the cable. The double twist includes a full aerial twist, located above the water surface and a full submerged twist, located below the water surface. The entire part of the fairing located below this complete double twist is no longer affected at all by what happens above it (its hulls are correctly oriented in the flow).

The configuration in which the fairing undergoes a double twist is stable but greatly degraded and it is highly likely to subsequently bring about large disturbances on the whole system.

The Applicant has discovered that when a fairing undergoes a full double twist, under certain conditions, the fairing will be greatly deteriorated in water and this deteriorated part will cause great damage to the faired cable or even to the whole faired system. during the winding of the cable and more precisely during its passage through the cable guide device.

By analyzing the complete double twist, the Applicant has found that the submerged twist can be considered to be “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 aerial counterpart, the aerial twist, remains located in the same place between the towing point R and the surface of the water S. It is not fixed relative to the cable along the cable axis but fixed by relative to the surface S of the water or to the towing point. When the cable is hoisted or lowered, the hulls undergoing the submerged torsion follow the movement of the cable which is hoisted or lowered while the aerial torsion remains fixed relative to the surface of the water. It follows that an unwinding of the cable plunges the submerged torsion to a greater depth while the aerial torsion remains in the same place relative to the surface of the water (the 2 twists then move away the one another). The figure 1C represents a situation in which the cable was unwound compared 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 a hoisting of the cable, compared to the situation of the figure 1B , according to the arrow shown on the figure 1D , brings up the submerged torsion while the aerial torsion always remains in the same place relative to the surface of the water (the two torsions then approach each other).

You then have to look at what happens for a twist of a submerged and towed lap as well. This twist which is deployed over a low height forces the fairings to navigate upside down or across the flow. 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 results in powerful torques which tend to force the hulls at line up in the flow but they come up against the stiffness of the twist turn which then increases. It happens then that a balance occurs and that the torsion of a turn is terribly reduced in height and the fairing undergoes violent forces which will tighten the submerged torsion under the effect of the towing speed. In other words, the complete turn of the fairing around the cable will be carried out over an increasingly shorter distance. Observations at sea have shown that the fairing column can make a full turn around the cable over a length of less than 50 cm. During towing, the hydrodynamic flow exerts a very high torque on the poorly oriented hulls which can go as far as the deterioration of the fairing or even the complete rupture of the hulls.

During the ascent of an immersed torsion, the fairing was long and very strongly constrained, it kept the memory of its deformation (that is to say of its twist) and the immersed torsion comes out of the water still very tight during hoisting and does not disappear during hoisting. We speak of residual torsion. Depending on the duration of exposure of the fairing to this submerged and towed twist, the submerged torsion will be able to become permanent or long enough to be absorbed, making it for a fairly long time totally incapable of engaging in the cable guide device although the continuity of the fairing is not broken. On the aerial torsion side there is no damage, there is indeed an applied torsion but at no time can it damage the cable.

When the still very tight submerged torsion then presents itself to the guide device, for example the pulley, the hulls affected by this submerged torsion cannot be placed correctly in the guide device, in particular in the pulley, they get stuck in the device guide. It is then the entire fairing column which then enters the guide device which is methodically destroyed if the hoisting is continued because, step by step, each hull follows the orientation of that which precedes it. This situation may even cause the guide device to break.

The invention proposes a fairing configured so as to limit the risks of the appearance of a double twist in order to limit the risks of damage to the cable fairing.

To this end, the invention relates to an elongated streamlined element intended to be at least partially submerged. The elongated fairing element comprises an elongate element and a fairing comprising a plurality of fairing sections, each fairing section comprising a plurality of hulls, the hulls comprising a channel receiving the elongated object and being profiled so as to reduce the hydrodynamic drag of the elongated object at least partially submerged, said hulls being pivotally mounted on the elongated element around the longitudinal axis of the channel, said hulls being linked together along the axis of the channel and being hinged together, the sections of fairing being free to rotate around the channel with respect to each other. The hulls of the same fairing section are linked together by means of a plurality of individual coupling devices, each individual coupling device making it possible to connect one of the hulls of said section to another hull of said section adjacent to said hull .

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 of a complete twist on said respective sections.

Advantageously, at least one fairing section has a height along the axis of the channel, defined as a function of the angular stiffness k of said fairing section and as a function of the length of rope LC of said hulls of said section, so as to prevent the formation a complete aerial torsion on said fairing section when the fairing section is subjected to a torsional torque less than or equal to a predetermined torque.

Advantageously, at least one section has a height, along the axis of the channel, defined as a function of the angular stiffness k of said fairing section and as a function of the length of rope LC of said hulls of said section so that the section is suitable for undergo a complete torsion and so as to prevent the formation of a complete aerial torsion on said fairing section when the fairing section is subjected to a torsional torque less than or equal to a predetermined torque.

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: $$\mathit{hmax}\le \frac{\pi \ast \mathrm{<figure-callout\; id="2"\; label="k\; F\; LC"\; filenames="imgf0001.png,imgf0007.png"\; state="\{\{state\}\}">k\; </figure-callout>}}{F{\mathit{LC}}^{}}$$

where F is a constant between 250 and 500.

Advantageously, at least one section among said sections comprises at least one end hull, adjacent to a single other hull belonging to said section, being a bevelled hull so that it has a bearing edge comprising a first bearing edge beveled with respect to the leading edge, the first bearing edge being arranged so that the distance between the leading edge and the first bearing edge, taken perpendicular to the leading edge, decreases continuously, along of 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 parallel axis at the leading edge. Each bevelled hull is for example an end hull.

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 of a complete twist on said respective sections.

Advantageously, the bearing edge is the trailing edge.

Advantageously, at least a first portion of the first bearing edge has a thickness less than a thickness of the hull in any longitudinal plane parallel to the leading edge and perpendicular to lateral faces of the hull crossing the first portion of the first edge d 'support, the lateral faces extending in respective planes perpendicular to the leading edge.

Advantageously, the end hull is dimensioned so as to be more resistant to a pressure force applied according to a perpendicular direction, at the leading edge and connecting the leading edge to the trailing edge, than the other hulls of the section.

Advantageously, the end hull comprises two parts joined or connected along the first bearing edge, the end hull being configured so as to be maintained in a deployed configuration when it is subjected to the hydrodynamic flow of water. , the two parts being arranged, relative to one another around the first bearing edge, so that the end hull has a trailing edge parallel to the leading edge and a constant section along the leading edge and configured to allow relative pivoting between the two parts around the first bearing 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 end hull changes from the deployed configuration to a configuration folded around the support edge.

Advantageously, the hulls are rigid.

The subject of the invention is also an elongated faired element intended to be at least partially submerged, comprising an elongated element faired by means of the fairing according to the invention, the elongated element being received in the channel, said hulls being pivotally mounted on the elongated element around the longitudinal axis of the channel and being immobilized in translation relative to the elongated element along the axis of the elongated element.

The subject of the invention is also a towing assembly comprising an elongated fairing element according to the invention, and a towing and handling device intended to tow the elongated fairing element while the latter is partially submerged, the towing device comprising a winch for winding and unwinding the elongated faired element through a guide device for guiding the elongated element.

Advantageously, the guide device is configured so as to make it possible to modify the orientation of a fairing of the fairing relative to the guiding device by rotation of the hull around the axis of the elongated element under the effect of the traction of the elongated element relative to the guide device when the hull has an orientation in which it is in abutment on the guide device and in which the line of action developed by the elongated element on the pulley extends substantially along the axis extending from the axis of the elongated element to the trailing edge.

Advantageously, the guide device comprises a first groove, the bottom of which 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 allow the hull to tilt, by rotation of the hull around the axis of the elongated element x under the effect of the traction of the elongated element relative to the guide device along its longitudinal axis, from an inverted position in which the hull is oriented trailing edge towards the bottom of the first groove, to an acceptable position in which it is oriented leading edge towards the bottom of the first groove.

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 hulls comprise a hull comprising a 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 curved surface forming a first concave curve in the radial plane of the pulley, the first concave curve being defined in a radial plane of the pulley so that, when the hull extends leading edge perpendicular to the radial plane, whatever the position of a hull in the first groove, when the nose of the hull is in abutment on the first concave curve and the elongated element exerts on the hull, in the radial plane, an effort of placing the nose of the hull against the pulley, said effort of cladding 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 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 y at less equal to a slip angle αt. The sliding angle 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 forming the external part of the tail of the hull and the material forming the surface delimiting the groove of the pulley.

• 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 19a 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 characteristics and advantages of the invention will appear on reading the detailed description which follows, given by way of nonlimiting example and with reference to the appended drawings in which:

• the figure 1A already described represents a faired cable, by means of rigid hulls axially linked together, towed partially submerged from its submerged part to a guide pulley in a situation in which the cable does not undergo double twisting, the Figure 1B represents the cable from the figure 1A in the same state of immersion (i.e. winding and unwinding) as on the figure 1A but undergoing a double twist; the figure 1C represents the cable from the figure 1A presenting the double twist of the figure 1B in a configuration in which the cable was unwound relative to the figure 1B ; the figure 1D represents the cable from 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 ship towing an object towed by means of a faired cable,
• the figure 3 schematically represents a portion of faired cable according to the invention by means of a fairing according to the invention,
• the figure 4a represents a section of a fairing of the fairing according to the invention according to the section plane AA represented on the 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 faired cable according to the invention penetrating a cable guide pulley,
• on the Figures 6a to 6b , there has been shown sections of a pulley according to the prior art, along the lateral face of the hull penetrating the trailing edge towards the bottom of the groove, when it comes to bear on the pulley ( figure 6a ) then after when the cable has been pulled to the right on the figure 5 (( figure 6b ) i.e. the cable has been hoisted and its tension has crushed the hull),
• on the figure 7 , a partial section is shown along a radial plane BB (see figure 5 ) an example of a pulley according to a first embodiment of the invention as well as a reference curve,
• on the figure 8a there is shown schematically 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 to the plane M on the figure 5 ) including the point of contact with the pulley, Figures 8b and 8c represent sections of the pulley according to planes successively occupied by the same lateral face of the hull when the cable is wound,
• in Figures 19a and 9b there are shown sections, in radial planes, of two examples of pulleys according to a third embodiment,
• on the figure 10 schematically shown, in a plane BB, lower and upper curves of a first curve at the bottom of the bath,
• on the Figures 11a to 11c there is shown, in successive planes parallel to the plane M of the sections of the pulley as well as the orientations successively adopted by the lateral face of the reference hull when the cable is wound, the hull arriving returned to the pulley of the figure 7 ,
• on the Figures 12a to 12c there is shown schematically 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 hen ( figure 12b ), in sectional view along the plane M visible on the figure 12a , in section view along the plane Q visible on the figure 12d ,
• on the figure 13 , there is shown schematically 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 an elongated fairing element comprising an elongated object coated with a fairing. The elongated object is 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 submerged. The elongated element is conventionally intended to be towed by a floating vessel. 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 the figure 2 , comprising an elongated element 1 faired by means of a fairing according to the invention. In the following text, the invention will be described in the case where the elongated element is a cable but it applies to other types of flexible elongated 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 in an appropriate manner. The towed body 101 is launched and taken out of the water by means of a winch 5 disposed 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 faired cable comprising:

• A winch 5 for winding and unwinding the faired 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, of the cable 1. In other words, the cable 1 is wound around the winch 5 ( or unwound by means of the winch) through the guide device 4.

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

The guide device makes it possible to guide 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 reel. 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 does not go below a certain threshold in this plane.

In the nonlimiting example represented on the figure 3 , the guiding device is a pulley 4. The guiding device can furthermore comprise inter alia a fairlead making it possible to secure the radius of the cable, and / or a slicing device making it possible to store the cable correctly on the reel and / or at less a deflector forming a surface making it possible to modify the orientation of a hull relative to the deflector by rotation of the hull around the axis of the cable under the effect of the traction of the cable during its winding / unwinding. The latter can be achieved by a pulley.

On the figure 3 , there is shown schematically a portion of cable 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 have been shown, each comprising 5 fairing hulls, but in practice, the fairing may include many more fairing sections comprising much more hulls.

The hulls are advantageously rigid. By rigid hulls is meant, in the present patent application, that the hulls are configured so as not to be substantially deformed under the effect of the hydrodynamic flow when they are immersed and 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 forces greater than those developed by the hydrodynamic flow. They are for example made of hard plastic material such as, for example, polyethylene terephthalate (PET) or polyoxymethylene (POM).

Each hull 13, 13a has a hydrodynamic profile, of the type shown in the figure 4a , in a plane AA perpendicular to the axis x of the cable (or axis of 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 which can differ from the hulls 13 by the characteristics which are explained below due to 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 receiving the cable 1. The nose 14 comprises the leading edge BA and the tail 15 comprises the trailing edge BF which are the end points of the hull 13 in the cutting plane. The hull 13 more particularly has in this plane a wing-shaped profile. The hull profile allows a less turbulent flow of water around the cable. The hydrodynamic profile for example has a teardrop shape or a NACA profile, that is to say a profile defined by the NACA which is an acronym of the Anglo-Saxon expression "National Advisory Committee for Aeronautics".

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

On the figure 4a , reference has been made to the length of rope LC of 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 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 from the second longitudinal face 23 in a direction perpendicular to the cord CO in the section plane 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 channel xc parallel to the leading edge BA. The length of the 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 able to pivot around 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 linked together by means of a coupling device 20 allowing the relative rotation of said hulls 13 relative to each other around the cable 1. The coupling device 20 links the hulls to each other both axially, that is to say along the towing cable but also in rotation about the cable 1. The coupling device 20 allows the relative rotation of the hulls with respect to the others around the axis of the cable, that is to say of the channel 16. This travel is authorized either freely or with a stop. The rotation of a hull around the cable does not then cause the adjacent hull to rotate. The travel 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 causes the adjacent hulls of the same section to rotate around the cable. Advantageously, the play 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 weakest resistance to the current caused by the movement of the cable in water. The coupling device allows this relative rotation with a maximum amplitude, that is to say a maximum angular movement. In this way, the rotation of a hull causes a rotation of the neighboring hulls and gradually that of all the hulls of the same section 12a or 12b. All the hulls of the same section adopt, as the cable rises, the same orientation relative to the drum, which makes it possible to wind the cable while keeping the scales parallel to each other in turn.

Advantageously, the coupling device 20 allows the relative rotation of the hulls with respect to each other so as to allow the cable to be wound around a winch, the lateral movement of the cable due for example to changes in course of the ship . The coupling device allows these relative rotational movements of the hulls with respect to each other with maximum respective angular deflections.

The coupling device 20 shown in 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.

When there is torsion of a fairing section, there is deformation of the fairing section. This deformation is obtained by elastic deformation of the coupling device 20 and / or of the hulls so that the fairing section opposes torsion because of its torsional stiffness. In other words, the fairing exerts a return torque in the opposite direction to that of the torque applied to the fairing to generate the torsion. These elastic deformations are twists. In the case where the fairing comprises the individual coupling devices 19, the individual coupling devices 19 deform elastically when the fairing is twisted. Conventionally, the hulls have a stiffness such that they also deform elastically when the fairing is twisted. These elastic deformations are twists.

Advantageously, the hulls 13 are immobilized in translation relative to cable 1 along the axis of cable x. This makes it possible to prevent the hulls 13 from compacting or distancing along the cable 1, which could result in problems of blocking the fairing 11 during the winding of the faired cable around the winch reel 5 or even in the passage of the guide 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 immersed 6 situated in the direction of the arrow f (called the head hull). The hulls being linked together, the blocking produced by the immobilization device on a hull 13a has repercussions on the other hulls of the same section. The installation of a hull immobilizer is not necessary, which limits the costs and the assembly time as well as the weight of the faired cable. As a variant, the section comprises several immobilization devices each cooperating with a hull of the section. The immobilization 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, around 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 distinct fairing sections 12a and 12b are free to rotate with respect to each other, around the axis of the channel, that is to say say around the cable 1. Each section 12a, 12b is relatively flexible in rotation around the cable even if a certain torsional stiffness is observed. This flexibility only increases with the length deployed. For this reason, the fact of cutting the fairing into sections of free fairings in rotation relative to each other makes it possible to limit the risks of formation of double twists, and therefore to limit the risks of deterioration of the fairing, since the twists of the sections fairings are not transmitted from one section to another. The fairing can be installed along the cable. In other words, the fairing extends over the entire length of the cable. Alternatively, the fairing extends along the cable over a length less than the length of the cable.

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

The heights h, of the respective fairing sections, that is to say their lengths along the axis x of the cable, are less than a maximum height hmax. As a variant, 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 this is not an obligation. The maximum height hmax is chosen so as to be sufficiently low to prevent the formation of a complete aerial torsion on the section, for example of a complete torsion on the section. The disturbed section can make a full turn on itself and realigns itself in the flow, since it is decoupled from its neighbors this section no longer disturbs them and there is no longer any aerial twist or submerged twist. This configuration makes it possible to prevent old complete submerged twists from entering the guide device and therefore limits the risks of damage to the fairing. Furthermore, this configuration makes it possible to avoid having to set up a monitoring procedure, by the crew, or a monitoring device aimed at detecting submerged torsions as well as a mechanical or manual procedure aimed at absorbing a double torsion detected or aimed at helping an immersed retentive torsion coming out of the water to enter the guide device without causing damage.

Advantageously, the height of at least one section, and preferably of each section, is defined so as to prevent the formation of a complete aerial twist of said fairing section when the fairing, or the elongated element faired by means of the fairing. , is towed under predetermined nominal towing conditions of the fairing, the fairing section being partially submerged. The aerial torsion is the torsion undergone by the aerial part, that is to say not immersed, of the fairing section.

The nominal towing conditions are defined by a nominal sea state, a nominal speed at which the cable is intended to be towed, i.e. the nominal speed of the ship, and the height at which is intended to be the towing point of the fairing above sea level. The nominal sea state, the nominal speed and the height of the towing point may be predetermined or may be included in predetermined respective nominal intervals. When the fairing is towed so that the fairing section is partially submerged under the nominal conditions, the fairing section is subjected to a torsional torque which is less than or equal to a predetermined maximum torque. This maximum torque is defined by the nominal conditions. The predetermined maximum torque can be obtained by calculation or empirically by measuring the torque exerted by the fairing section under nominal conditions.

The maximum height of the fairing section is defined so as to avoid the formation of a complete aerial torsion on the partially submerged fairing section when the fairing section is subjected to a torsional torque less than or equal to the predetermined maximum torque.

The height of the fairing is empirically defined by varying the length of the fairing section under the most demanding nominal towing conditions, generating the maximum torque so as to obtain a height such that it avoids aerial torsion. complete of the fairing section. It can also be determined by simulation by modeling the behavior of the fairing section under the most restrictive nominal conditions and by varying the height of the section until the desired effect is obtained.

Consequently, when the fairing section is towed under nominal conditions and partially submerged, the aerial part of the fairing is subjected to a torsional torque due to the waves. If this torque is less than or equal to the maximum torsional torque, it will undergo a torsion but the forces applied at the level of the guide device and in the submerged part are balanced so that the fairing will make a full revolution on itself around the elongated element (or around the channel) before its aerial part undergoes a complete twist. Consequently, the appearance of a complete aerial twist and therefore, the appearance of a double twist is avoided.

In a preferred embodiment, the height of at least one section, and preferably of each section, is chosen so that the section is able to undergo a complete twist. The height of the section is therefore large enough to allow this twisting. However, this height is also chosen, as above, so as to prevent the formation of a complete aerial torsion on said fairing section when the fairing, or the elongated element faired by means of the fairing, is towed under towing conditions. predetermined nominal fairings, the fairing section being partially submerged. In other words, the height of the section is low enough so that, when the fairing (or the cable is faired) is towed, partially submerged and is subjected to a maximum torque, it cannot be subjected to aerial torsion. On the other hand, it can undergo a complete torsion if it is subjected to a torque greater than the maximum torque.

The height of the section is defined as a function of the angular stiffness in torsion k of said fairing section, as a function of the length of rope LC of said hulls of said section and as a function of nominal towing conditions.

Où k est la raideur angulaire en torsion du tronçon de carénage 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 longitudinal du bord d'attaque.A fairing section T undergoing a twist by an angle θ around the x axis of a cable (or of channel 16) is subjected to a torque C applied around the x axis of the cable 1. The torque C allowing to get this twist angle is given by the following formula: $$\mathrm{VS}=\frac{\mathit{k\theta }}{h}$$

Where k is the angular stiffness in torsion of the fairing section around the cable (or channel) axis expressed in Nm ² / radians, h is the height of the fairing section, i.e. the length of the fairing section along the cable axis 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. The greater the fairing sections have a stiffness around the axis of the cable, the more they can have a significant height. The greater the length of the fairing cord, the more the fairing section will be disturbed by the stresses of the sea and the towing conditions and the lower the maximum height of the fairing sections. The torsional disturbances caused by the stresses of the sea and the towing conditions are proportional to the surface of the hulls of the section (therefore to the length of the rope) and to the arm lever (therefore the length of the fairing rope). The maximum height hmax is therefore given by the following formula: $$\mathit{hmax}\le \frac{\pi \ast \mathrm{<figure-callout\; id="2"\; label="k\; F\; LC"\; filenames="imgf0001.png,imgf0007.png"\; state="\{\{state\}\}">k\; </figure-callout>}}{F{\mathit{LC}}^{}}$$

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

The constant F is between 250 and 500. F depends on the maximum speed at which one wishes to tow the cable. If one wishes 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 fairings having an angular stiffness in torsion k of the order of 4 to 5 Nm ² / rad, and a length of LC cord 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. In fact, the fact that the fairing according to the invention minimizes the risks of the formation of double twists makes it possible to limit the risks of deterioration of the fairing linked to the aging of the submerged twists without them entering a guide device. The fairing according to the invention therefore limits the needs in terms of cable maintenance.

Advantageously, the device for guiding the towing assembly according to the invention is configured so as to make it possible to modify the orientation of a fairing of the fairing relative to the device for guiding by rotation of the hull around the axis of the cable, under the effect of the traction of the cable relative to the guide device (along the cable axis), when the hull has an orientation in which it is in abutment on the guide device and in which the line of force action 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 guide 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 faces tail up. The upward and downward orientations are defined with respect to a vertical axis linked to the winch.

These configurations make it easier to wind the shrouded cable on the winch. When the cable is wound around the winch reel, the first hull of each section to come out of the water goes up towards the guide device and, not being linked to the hulls of the previous section, it will turn down the trailing edge under the effect of gravity, bringing with it the following hulls of the same fairing section. If the guide device does not allow such a reversal, the hulls will arrive badly oriented on the winch reel (we prefer to wind the hulls trailing edge upwards to avoid damage to the fairing because the leading edge is more resistant ).

To this end, the guide device comprises a guide or a set of guides allowing the orientation or tilting of the hull to be changed. This guide or guide assembly can for example comprise a pulley and / or a deflector or any other device making it possible to modify the orientation of the hulls around the axis of the cable. A nonlimiting 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 of the grooved type, so as to define a housing intended to receive the hull to ensure its tilting. These guides may be able to follow the cable in the event of lateral movement of the cable parallel to the axis of the pulley (or of the winch), by being for example pivotally mounted about a substantially vertical axis.

Up to now, all the towing pulleys have been configured so as to pass the hulls nose towards the bottom of the groove and tail towards the outside of the groove. This arrangement is logical since the towing cable, seat of the efforts, 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 arrangement is made necessary because of the links between all of the hulls. Leaving the sea and arriving at the towing pulley, the hulls which, during their aerial journey, tend to orient themselves on the trailing edge downwards (upside down therefore) are thus straightened step by step thanks to the links inter-hulls. When a hull is well positioned in the groove of the pulley, during hoisting (but also unwinding) all the following will gradually straighten and pass the pulley as well as possible.

Furthermore, the devices allowing the fairing to be turned over (or rectifiers) are ineffective when installed downstream of the pulley, seen from the free end of the cable because the position of the cable has at this point at least two degrees of freedom: longitudinal and lateral and current rectifier devices are not able to correctly follow the cable in these two directions or they are complex devices.

In the case of a pulley with a narrow V-groove, if the guide device does not have a turning device downstream of the pulley seen from the free end of the cable or if this device does not perform hulls entering the tail down in the pulley will be able to get stuck in the groove and, if they are not dimensioned to withstand the force exerted by the cable in this orientation, they will deform and cause the following hulls to deform. This situation is represented on the figures 5 and 6a to 6b . On the figure 5 , there is shown a portion of a faired cable 1 penetrating a pulley P with groove 50. In this figure, the cable 1 is wound which then enters the pulley in the direction of the arrow. In this figure, the xp axis 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 towards the outside of the groove and leading edge towards the groove. The remarkable hull 13a is the hull at the head 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 submerged 6. The hull 13a is present 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 lateral edge 18 connecting the trailing edge BF and the leading edge BA of the hull of head is 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 situated to the right of the plane M on the figure 5 because the cable 1 has been hoisted, that is to say pulled along the arrow shown in the figure 5 enter here figure 5 and the figure 6b , advancing the remarkable hull 13a in the throat. The groove of the pulley has a V-shaped section with 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 pulley leading edge upwards, the following hulls linked to this hull will also take this orientation during winding of the cable. On the other hand, if a head hull 13a arrives at 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 upward trailing edge under the effect of the traction of the cable relative to the groove of the pulley along its axis. The tension of the cable forces the head hull 13a to descend towards the bottom of the groove. Indeed, when pulling the cable along its axis in the pulley, it develops a force, on the hull, oriented according to the force action line indicated by the arrow on the figure 6a . However, if the hull is not dimensioned to resist this constraint, it deforms and breaks (or deteriorates) as shown in the figure 6b .

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

To this end, the invention consists in providing a towing assembly comprising a cable guide device disposed downstream of the winch seen from the end of the cable intended to be submerged, the guide device comprising a first groove the bottom of which is formed by the bottom of the groove of a pulley, the first groove being configured so as to allow a hull of the fairing to be tilted, 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) towards the bottom of the first groove, that is to say the trailing edge towards the outside of the groove. The dimensions and 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 of the fairings of the fairing, of the x axis of the elongated element 1, of the length of rope LC des hulls and the maximum thickness E of the hulls so as to allow the hull to be tilted 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 thin end of the tail) is located at a shorter distance 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 the pulley pivots relative to the winch, that is to say relative 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 in a calm sea state when the towing device is fixed to a naval vessel or ship. . The bottom 26 of the groove of the pulley forms a circle of radius R, the center of which is on the axis of the pulley.

On the figure 7 , 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 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 has also been 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 the 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 Iv, taken along a straight line d parallel to the axis of the pulley, is at least equal to one threshold width Is given by: $$\mathit{ls}=0.7\ast \mathit{lid}$$

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

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

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 of the hulls of the fairing of the cable axis, taken parallel to the CO cord of the hulls, where LC is the length of the hull cord 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. Turning 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 limit 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 external part of the tail of the hull and the material forming the surface delimiting 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 is merged 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 apart by the width Iv 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 extremes 33, 34 and the bottom 26, combined 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 cutting plane BB.

Consequently, to ensure the desired reversal, the first concave curve 25 delimiting the first groove 24 may have the profile visible on the figure 7 or else 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 of the pulley axis pulley (Radius R of the pulley). In other words, the first concave curve is located at all points, in the space delimited by 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 of the passing pulley by points 33 and 34.

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

On the figure 14 , there is shown in dotted lines, in a radial plane a portion 250 of a first concave curve respecting an advantageous characteristic of the invention. 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 is in abutment on the first concave curve and the cable 1 exerts on the hull 13, in the radial plane, an effort of plating 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 n is not in contact with the first concave curve or is in contact with part 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 at the trailing edge of the hull, an angle γ at least equal to a sliding angle αt. The sliding angle is given by the following formula: $$\mathit{\alpha t}=\mathit{Arctan}\left(\mathit{Cf}\right)$$

This characteristic makes it possible to prevent 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, the hull is slid in the event of lateral cable thrust. In other words, a pulley having a profile as defined with reference to the figure 14 allows the hull to be turned over from an inverted position to an acceptable position.

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

In practice, for an angle αt of the order of 10 °, a first curve forming a curved line having at all points a radius of curvature at least equal to half the length of the hull cord LC makes it possible to ensure the sliding of the hull in case of lateral thrust of the cable. A curved line is a line without a sharp or protruding 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 αt with the line dp, the radius RA of this circle is approximately equal at 55% of the length of the hull LC cord, which is greater than the value of 50% retained above.

Advantageously, the dimensions and the shape of the first groove profile 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 of the hulls of the fairing, a length of LC chord of the hulls and a maximum thickness E and possibly as a function of 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 an inverted position to an acceptable position without deforming this reference hull.

On the realization of the figure 7 , the width of the first groove Igb is equal to the width of the V Iv. Alternatively, the first groove extends beyond the end points. It can include the groove of the pulley only or include the groove of the pulley and be delimited on either side of the pulley by deflectors or vertical flanges (i.e. perpendicular to the axis of the pulley) or substantially vertical. The first groove may also be the groove of the pulley which comprises, beyond the V or above the V of the 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 movement.

On the realization of the figure 7 , the first groove is the groove 24 of the pulley. As a variant, the first groove comprises the groove of the pulley. The bottom of the first groove is the bottom of the pulley groove. In contrast, the first groove extends beyond the groove of the pulley. It is for example delimited 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 can be fixed relative to the pulley or movable in rotation relative to the pulley around the axis of the pulley. Advantageously, the first groove comprises lateral edges making it possible to limit the lateral clearance of the cable. The lateral edges may extend completely within the part situated between the two extreme points or else partially and also extend 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 according to all the 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 the pulley profile according to the invention is obtained as shown in the figure 7 . The plaintiff started from the observation that the V of the figure 6a so that the tail can clear on the side when winding 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 lateral face 18 of the head hull 13a of the segment 12b coming into contact with the pulley. The side face includes the point of the hull that first comes into contact with the pulley. The pulley has an open V-shaped profile for turning. In this figure, the pulley 40 comprises a groove 44 in V. The remarkable hull 13a is supported on a first tab of the V 45 leading edge towards the bottom 46 of the groove 44. The opening of the groove αg is such that the angle formed between the line of force action (represented by the arrow represented in the hull) and the second leg 47 αf is greater than 90 °. In this case, the tail is given an escape route which allows it to turn around according to the arrows shown on the figure 8a to adopt the position represented on the figure 8c passing 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 line of force 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 leg 45. This is why the opening of the V αg in the plane M, which is at least equal to twice the limit angle αi is substantially equal to αf. Consequently, the opening of V αg is greater than 90 °. To take account of the friction between the tail of the hull and the surface of the groove, the limit opening αg = 2 ^∗ αi is at least equal to 95 ° and preferably at least equal to 100 °.

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

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

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

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

However, 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 hulls of the fairing of the axis of the cable taken parallel to the cord CO of the hull 13a. It is defined as follows: $$\mathit{BECAUSE}=R-\mathit{Rcos\beta }$$

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

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

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

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

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

It can have at least from the first extremal point 33 to the second extreme point 34 a V shape or have several sharp or projecting angles AS as shown in the Figures 9a and 9b . In other words, the curve substantially forms a broken line. In these figures, the curves have a sharp or projecting 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 in ensuring the reversal of the hulls than the V-shaped 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. As a variant, the first curve has 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 in the figure 7 , the first curve 25 is, between the extreme points 33, 34, a curved line. In other words, it is a concave curve devoid of a sharp or salient angle (in the mathematical sense of the term). We speak of a U-shaped profile. In other words, the curve never includes 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 curve), it must have a width at least equal to lid so that the inversion is guaranteed. When the first groove (or first curve) has a section such that the first curve is U-shaped, then it can have a width less than up to 0.7 ^∗ lid because it does not have d sharp angles in which the bottom of the hull may get caught. In this case, the opening of the V can also be less 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 over 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 will take place.

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

• 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 area, this central area 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 merged 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 hatched zone) 10:

• an upper curve SUP having a first radius of curvature R1 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 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, lateral portions LAT1 and LAT2 connecting the central portion at the extreme points 133, 134 and having a second radius of curvature R2 equal to 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 each other 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 parts extending substantially perpendicularly above the extreme points of the V so as to prevent the cable from leaving the first groove during a vertical movement of the cable. These flanges are integral with the pulley or belong to the pulley or are fixed relative to the axis of the pulley.

The first curves between the upper curve and the lower curve have the advantage of verifying the angular condition making it possible to prevent the hull from preventing lateral movement of the cable.

On the Figures 11a to 11c there has been shown, in successive planes parallel to the plane M, orientations successively adopted by the lateral face of the reference hull comprising the first point to come into contact with the pulley, when the cable is wound. The hull 13a arrives at the trailing edge downwards ( figure 11a in plane M) and when the cable is pulled, it pivots around the axis of the cable (see figure 11b ), under the effect of the cable tension, 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 groove (( figure 11c ). This profile facilitates and simplifies the tilting of a hull because the flattened central portion of the groove of the pulley implies a significant distance between the axis of the reaction of the groove of the pulley on the hull (axis going from the edge trailing towards the center of the circle portion 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) due to the large distance between the axis of the cable and the center of the circle portion formed by the central portion. This profile also allows the cable and its fairing which are placed substantially flat to come to rest safely on the sides of the pulley when the cable is biased laterally (that is to say parallel to the axis pulley) in the event of a turn of the vessel, for example. If the cable and the leading edge of the fairing are positioned on the correct side, they remain there. If they are on the wrong side, the profile of the pulley allows an almost smooth reversal which allows the cable (where the forces 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 straightening of a hull coming to bear on the pulley with a trailing edge orientation towards the bottom of the groove pulley and leading edge vertical to the trailing edge. The hull carries with it the hulls to which it is linked to rotate about 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 linked together to rotate about the cable in the event of a break in 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 head 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 submerged. It also makes it possible to straighten the hulls of a faired cable comprising hulls which are all free to rotate about the cable relative to each other. It also makes it possible, by virtue of its width, to ensure the guiding of a cable organized in a single section having a residual twist (very tight submerged twist not absorbed when the pulley passes) without deforming the hulls which is not not possible with a narrow V-pulley.

The guide device according to the invention is effective 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 relative 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 until a situation in which the trailing edge is located vertically leading edge. For example, in the case of the pulley at the bottom of the bathtub, the hull is returned to a position in which it is substantially flat (trailing edge slightly raised upwards). It must therefore pivot about ¼ turn against ½ turn (if it were to adopt the trailing edge position above and vertically from the leading edge) which facilitates the operation of straightening the hull by the pulley .

Advantageously, the guide device comprises, between the winch and the pulley, a straightening device making it possible to orient the hulls which come out of the pulley in the direction of the winch around 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 vertical to the leading edge. These devices are only really effective when the position of the cable is perfectly known (and this is the case at the output 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 to the axis of the channel xc. By constant section is meant a section having substantially the same shape and the same dimensions in all the transverse planes, whatever their positions along the leading edge between the lateral faces 17, 18. In other words, the trailing edge BF is substantially parallel to the leading edge BA over the entire width I of the hull. The width I 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 bevelled hull. A bevelled hull is a hull which comprises a bearing edge BAPa comprising a first bearing edge in bevel Bza relative to the leading edge BAa, the bevel being produced so that the distance between the leading edge BAa and the first bevel bearing edge Bza, taken along an axis perpendicular to the leading edge BAa and to the axis xc of the channel 16 varies linearly along the axis xc. By first bevel bearing edge Bza is meant a first bearing edge Bza which extends longitudinally substantially along a straight line which is at an angle or inclined relative to the leading edge BAa. The first bearing edge Bza extending longitudinally in a first plane containing a plane or parallel to the plane defined by the leading edge BAa and the chord CO of the hull. In other words, the first bearing edge Bza is biased relative to the leading edge BAa in this first plane.

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

On the realization of the figure 12b , this lateral face 180 is the lateral face of the hull 130a furthest from the free end 6 of the cable (visible on the figure 2 ) in the opposite direction of the arrow. The other lateral face 170 is the lateral face of the hull 130a closest to the free end 6 of the cable. This characteristic makes it easier to turn over the hull 130 when it comes to bear on the pulley by its trailing edge, during the winding of the cable, that is to say during the pulling of the cable relative to the pulley axis xp according to arrow f. Indeed, on the figure 12b , the position P 'has been shown 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 pulling of the cable relative 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 cable 1 perpendicular to the axis of cable x. Also shown is the position P, on the pulley 4, of the point where a hull 13 which would have had the shape shown on the Figures 4a and 4b would have come into contact with the pulley P. This point is located at a distance dB from the cable 1 perpendicular to the axis of the cable x. The distance dB 'is less than the distance B, therefore, the inversion of the hull is facilitated and therefore the inversion 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 making it possible to modify the orientation of the hull relative to the guide device by rotation of the hull about the axis of the cable. In particular, the beveled support edge makes it possible to facilitate the reorientation of a hull in any guiding device making it possible to modify the orientation of the hull relative to the guiding device by rotation of the hull around the axis of the cable (or channel) when the hull comes to bear on a bearing surface of the guide device by the bearing edge. In other words, the beveled support edge facilitates in particular the reorientation of the hull by any guide device comprising a surface opposing the traction of the faired cable during the winding or during the unwinding of the cable. The invention works, for example, with guiding devices making it possible to follow the cable in the event of lateral and / or vertical movement of the cable. In general, the presence of a bevelled hull makes it possible to limit the risks of deterioration of the fairing, in particular in the presence of a double twist by facilitating the tilting of a hull at its entry into a guide device, which limits the risk that the fairing gets stuck in the guide device.

This embodiment also has an advantage in the case of a pulley having a constant profile, and more particularly of a pulley according to the invention. Indeed, the contact point P 'is located in a plane M' located at a distance D 'smaller than the distance D at which the plane M is located (including the point P), relative to the axis of the pulley, parallel to the axis of the cable x. Consequently, the groove of the pulley is less deep in the plane M 'than in the plane M. In fact, 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 less deep according to the plane M 'than according to the plane M implies that the pulley is flatter according to the plane M than according to the plane M' at least at the bottom level (that is to say say at the level of the central portion of the curve delimiting the throat). If the hull comes into contact on the central portion of the pulley at the bottom of the bathtub, the central portion is flatter in the plane M 'than in the plane M, in other words, the radius of the contact surface at point P is more important in the plane M 'than 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 bevelled hull comprising the bevel is the hull 130a at the head of the section, that is to say the hull farthest from the end of the cable intended to be immersed. This makes it easier to tilt the hull 130a during the winding of the cable and to facilitate the tilting of the entire section 120 because the hull, being linked in 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 head hull 130a is a hull which is adjacent to a single other hull 130b belonging to the same section 120. The first bearing edge Bza of the head hull 130a is arranged so that the distance between the leading edge BAa and the first bevel bearing edge Bza decreases continuously, along an axis parallel to the leading edge BAa, from a first end E1 of the first support edge Bza to a second end E2 of the first edge d 'support Bza further from the other hull 130b than the first end E1, along the axis parallel to the leading edge BAa.

As a variant, the bevelled hull is the bottom hull of the section, that is to say the hull closest to the end of the cable intended to be submerged. This makes it easier to tilt the hull during the unwinding of the cable (when the hull comes to rest on the pulley on the other side of the pulley relative to the axis of the pulley) and to facilitate the tilting of all section because the hull (by propagation of the rotational movement over the entire section). The tail hull is a hull which is adjacent to only one other hull belonging to the same section. The first support edge is configured so that the distance between the leading edge BAa and the first beveled support edge decreases, along the leading edge BAa, from a first end of the first support edge opposite the other hull to a second end of the first bearing 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, ensures the tilting of all the hulls of the fairing sections, without having to provide only bevelled hulls over the entire fairing, which would have the effect of limiting the performance of the fairing in terms of reducing drag.

Advantageously, each section comprises at least one end hull (head or tail) comprising a beveled edge. The other hulls are not beveled hulls. They do not include a first beveled support edge. The bearing edge is the trailing edge and is substantially parallel to the leading edge over its entire length. In an unclaimed 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 submerged. In this case, the hull at the head of the section is advantageously a hull comprising a beveled bearing edge arranged as for the head hull previously described.

In another variant not claimed, the section extends over the entire length of the cable.

In all the fairing configurations (of the type comprising a section, several sections or comprising hulls all free to rotate with respect to one another around the elongated element), all the hulls could be beveled hulls. This would facilitate the tilting of each hull in the event of an inter-hull connection break downstream of the hull seen from the pulley, when the hulls are initially linked. In the case where the hulls are free to rotate with respect to each other, this makes it easier to tilt each hull on arrival on a guide device. More generally, the bevelled hull avoids having to link the hulls to each other and therefore makes it possible to limit the costs of the fairing and the time for assembling the fairing.

If we want to facilitate the reorientation of the hulls in the event of winding of the cable, the bevel is made so that the distance between the leading edge BA and the first bevel bearing edge decreases, along the axis xc , from the end of the first support edge closest to the end of the cable intended to be immersed to the end of the support edge opposite the end of the cable intended to be immersed and vice versa if wishes facilitates 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 bevel bearing edge Bza and a 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. The first bevel bearing edge is connected to the lateral face 180 and to the second bearing edge Bla, in the direction of the leading edge, by connecting rounds or chamfers. The maximum length of rope LC is the distance between this second bearing edge Bla and the leading edge. As a variant, the bearing edge does not have a second bearing edge Bla extending parallel to the axis x. The bevel extends substantially over the entire width of the hull and is advantageously, but not necessarily, connected to the lateral faces by connection fillets or chamfers.

As seen on figure 12c and 12d representing sections of the hull according to respective planes N and Q, represented the figure 12a , parallel to the leading edge and perpendicular to the lateral 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 e2 less than the first thickness e1 of the thick part. 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 in the thin part. 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 therefore to limit the risks that the hull will get stuck on the guide device. As a variant, the chamfers extend over the entire length of the first bearing edge.

As a variant, the first portion of the leading edge Bza1 is connected to the lateral faces by respective bulged surfaces. By swollen surfaces is meant convex curved surfaces. This embodiment also makes it possible to limit the thickness of the bearing edge. As a variant, the curved surfaces extend over the entire length of the first bearing edge. Chamfers and curved surfaces are two non-limiting technical solutions which make it possible to obtain the characteristic that at least a first portion of the first bearing edge Bza1 has a thickness e1 less than the thickness of the hull in any longitudinal plane parallel to the edge of attack and perpendicular to the lateral faces of the hull crossing the first portion of the first bearing edge Bza1. The thickness of the hull in a cutting plane is the distance separating the first longitudinal face 122 from the second longitudinal face 123 in a direction perpendicular to the cord CO in the cutting plane of the hull. Advantageously, the first portion Bza1 has the same thickness as the second bearing edge Bla which extends parallel to the axis x and is located at a fixed distance from the leading edge along the axis x.

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

On the figure 13 , the support edge BAPb connects the two lateral faces 270, 280. The hull 230 is formed of two parts 231, 232 joined together along the first bevel support edge Bzb. The hull is configured to be kept in a deployed configuration (visible on the figure 13 ), when subjected to the hydrodynamic flow of water, in which the two parts 231, 232 are arranged, one with respect to the other around the first bearing 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 length of the rope is constant. The hull is kept in the deployed position as long as the relative pivoting torque between the two parts around 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 support 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 arrow), when a relative pivoting torque between the two parts 231, 232, applied around the the axis formed by the first support edge Bzb exceeds the threshold so that the end hull changes from the deployed configuration to a configuration folded around the support edge. The axis formed by the first support edge is an axis contained in the first support edge and parallel to the longitudinal axis of the first support 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 bearing edge Bzb. In the deployed position, the hull is unfolded. This embodiment makes it possible to limit or avoid the performance reductions in terms of reduction of the hydrodynamic drag 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 support edge delimited by the first support edge Bzb, the second support edge (if there is one) Blb, the leading edge BA, one face lateral 280 and the portion of the other lateral 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 situated 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 deform substantially when the relative pivoting torque between the two parts around the first bearing edge is less than or equal 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 guide device. The second part can, 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. As a variant, the two parts have a rigidity such that they do not deform under the effect of a torque greater than the threshold but are linked by a pivot link around the first bearing edge and the hull comprises a stabilization device configured to maintain the two parts in the relative deployed position when the relative pivoting torque is less than or equal to the threshold and so as to allow the rotation between the two parts so that they pass in the relative folded position around the first bearing edge when the torque exceeds the threshold. The coupling device is for example a device comprising a fuse or a compression spring.

Advantageously, at least one bevelled hull or each bevelled 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 considered (which are not bevelled). This characteristic makes it possible to limit the risks of deformation and breakage of the hulls when they engage in the guide device, turn around and pass through this guide device. For this purpose, this hull is for example made of a harder material than the other hulls and / or it includes ribs ensuring this additional reinforcement. Advantageously, the fairing comprises at least one reinforced bevelled end hull and cooperating with the immobilization device. This makes it possible to reduce the costs and possibly the weight of the fairing because only the beveled hull or hulls differ (s) from the others, all the others being identical.

The invention also relates to an assembly comprising a vessel, the towing assembly being carried on board the vessel. The ship is intended to move at nominal speed through a nominal sea state. The towing assembly is installed on the vessel so that the towing point is located at a nominal height.

Claims (15)

1. A faired elongated element intended to be at least partially submerged, comprising an elongated object and a fairing, the fairing comprising a plurality of fairing sections (12), each fairing section (12) comprising a plurality of conduits (13), the conduits comprising a channel (16) receiving the elongated object and being streamlined so as to reduce the hydrodynamic drag of the at least partially submerged elongated object, said conduits (13) being pivotally mounted on the elongated object about the longitudinal axis of the channel (16), said conduits (13) being connected together along the axis of the channel and being hinged together, the fairing sections (12) being free to rotate about the channel one relative to the other, wherein the conduits of the same fairing section are connected together by means of a plurality of individual coupling devices (19), each individual coupling device allowing one of the conduits of said section to be connected to another conduit of said section adjacent to said conduit.
2. The faired elongated element as claimed in claim 1, wherein the fairing sections have respective heights along the axis of the channel, defined as a function of the angular stiffnesses k of the respective fairing sections and as a function of the chord length LC of said conduits of said respective sections so as to prevent a full twist from forming on said respective sections.
3. The faired elongated element as claimed in any one of the preceding claims, wherein at least one fairing section has a height along the axis of the channel, defined as a function of the angular stiffness k of said fairing section and as a function of the chord length LC of said conduits of said section, so as to prevent a full aerial twist from forming on said fairing section when the fairing section is exposed to a torsion torque that is less than or equal to a predetermined twist torque.
4. The faired elongated element as claimed in claim 1, wherein at least one section has a height, along the axis of the channel, that is defined as a function of the angular stiffness k of said fairing section, as a function of the chord length LC of said conduits of said section, so that the section is able to undergo a full twist and so as to prevent a full aerial twist from forming on said fairing section when the fairing section is exposed to a twist torque that is less than or equal to a predetermined torsion torque.
5. The faired elongated element as claimed in any one of claims 2 to 4, wherein the fairing sections have respective heights below a maximum height hmax, such that: $$\mathit{hmax}\le \frac{\pi \ast k}{F{\mathit{LC}}^2},$$

   

   where F is a constant between 250 and 500.
6. The faired elongated element as claimed in any one of the preceding claims, wherein at least one section from among said sections comprises at least one end conduit, adjacent to only one other conduit belonging to said section, which conduit is a chamfered conduit such that it has a support edge comprising a first support edge (Bza) that is chamfered relative to the leading edge (BA), the first support edge (Bza) being arranged so that the distance between the leading edge (BA) and the first support edge (Bza), taken perpendicular to the leading edge (BA), continuously decreases along an axis parallel to the leading edge, from a first end (E1) of the first support edge (Bza) up to a second end (E2) of the first support edge (Bza) further away from the other conduit (130b) than the first end (E1), along the axis parallel to the leading edge.
7. The faired elongated element as claimed in claim 6, wherein each chamfered conduit is an end conduit.
8. The faired elongated element as claimed in any one of claims 6 to 7, wherein the end conduit is designed 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 conduits of the section.
9. The faired elongated element as claimed in claim 6, wherein the end conduit comprises two adjacent parts (231, 232) along the first support edge (Bzb), the end conduit being configured so as to be held in a deployed configuration when it is exposed to the hydrodynamic flow of the water, the two parts (231, 232) being disposed one relative to the other around the first support edge (Bzb), so that the end conduit has a trailing edge parallel to the leading edge (BA) and a constant section along the leading edge and is configured so as to allow relative pivoting between the two parts (231, 232) around the first support edge (Bzb) when a relative pivoting torque between the two parts (231, 232), applied around an axis formed by the first support edge (Bzb), exceeds a predetermined threshold, so that the end conduit transitions from the deployed configuration to a stowed configuration folded around the support edge.
10. The faired elongated element as claimed in any one of the claims, wherein the support edge is the trailing edge.
11. The faired elongated element as claimed in any one of the preceding claims, wherein the conduits are translationally immobilised relative to the elongated element along the axis of the elongated element.
12. A towing assembly comprising a faired elongated element as claimed in any one of the preceding claims and a towing and handling device intended to tow the faired elongated element while said element is partially submerged, the towing device comprising a winch (5) for winding and unwinding the faired elongated element (1) through a guide device (4) for guiding the elongated element (1).
13. The towing assembly as claimed in the preceding claim, wherein the guide device (4) is configured so as to allow the orientation of a conduit (13a) of the fairing (12) to be modified relative to the guide device (4) by rotating the conduit (13a) about the axis of the elongated element (1) under the effect of the traction of the elongated element (1) relative to the guide device (4) when the conduit (13a) exhibits an orientation in which it is in abutment on the guide device (4) and in which the line of action established by the elongated element (1) on the pulley (4) substantially extends along the axis extending from the axis of the elongated element up to the trailing edge (BF).
14. The towing assembly as claimed in the preceding claim, wherein 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 demarcated by a first surface (25) 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 allow the conduit to be rocked, by rotating the conduit about the axis of the elongated element x, under the effect of the traction of the elongated element relative to the guide device along its longitudinal axis, from a returned position, in which the conduit is oriented from the trailing edge towards the bottom of the first groove, to an acceptable position, in which it is oriented from the leading edge towards the bottom of the first groove.
15. The towing assembly as claimed in any one of claims 13 to 14, wherein the conduits comprise a conduit comprising a nose (14) receiving the elongated element and comprising a leading edge (BA), a tail (15) having a tapered shape extending from the nose (14) and comprising a trailing edge (BF), the first curved surface forming a first concave curve in the radial plane of the pulley, the first concave curve being defined in a radial plane (BB) of the pulley so that, when the conduit extends from the leading edge (BA) perpendicular to the radial plane (BB), irrespective of the position of a conduit in the first groove (24), when the nose (14) of the conduit (13) is in abutment on the first concave curve and when the elongated element (1) exerts, on the conduit (13) in the radial plane, a force for pressing the nose (14) of the conduit (13) against the pulley, said pressing force Fp comprising a component CP perpendicular to the axis of the pulley and a lateral component CL, with the trailing edge (BF) of the conduit (13) not being in contact with the first concave curve or being in contact with part (251) of the first concave curve, which forms, with a straight line dp of the radial plane perpendicular to the axis xa that extends from the axis of the elongated element x up to the trailing edge of the conduit, an angle γ that is at least equal to a slip angle αt, the slip angle being provided by the following formula: $$\mathrm{\alpha }\mathrm{t}=\mathrm{Arctan}\left(\mathrm{Cf}\right),$$

    

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

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