FR2821647A1 - OMNIDIRECTIONAL SUBMERSIBLE HYDRAULIC TURBINE WITH PERPENDICULAR AXIS - Google Patents

Abstract

The invention concerns a squirrel-cage type turbine whereof the bars are linked to profiled blades (2), each of which being arranged, when the turbine is not operating above the water surface, such that it remains perpendicular to the radius (R) with which it is associated. Said turbine is immersed in a water current perpendicular to its shaft (3), by being mounted either on a floating craft (7) or on a heavy base (8) anchored on the floor of the water expanse. Its omnidirectional character enables it to operate in so-called rotary tidal currents. Said turbine, even if there is a large number of them beneath the water surface, can be entirely invisible and not obstruct navigation, thereby preserving the integrity of natural sites. The blades, or their linkage with their associated bar, are flexible and elastic so as to be better adapted to the angles of attack of the relative flow on each blade, for energy gain and very easy starting.

Description

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 This patent application is presented under the title: submerged omnidirectional hydraulic turbine with axis perpendicular to the water current and applications.

 Modern devices for producing energy from a natural flow of water are generally impressive achievements. They most often require the construction of large dams, whether for freshwater reservoirs or the exploitation of tidal energy. The natural sites are then considerably upset, which is not without drawbacks, especially from an ecological point of view.

 However, there are still some small and old installations using small watercourses, such as mills, whose yield is extremely low. There is a demand, however, for these small installations in isolated sites, for local energy production.

 No realization seems to exploit the movement of water "in the raw state", that is to say by taking energy directly from its natural movement of flow. The hydraulic turbine proposed here, which can fill this gap, is characterized in particular by a very great simplicity.

 It takes the form of a rotor representing a "squirrel cage" (Figure 3) conventionally consisting of two parallel discs (1) and (1 '), the bars of which are here replaced by blades (2) profiled in airplane wings (or thin planes taking the place of rudimentary realizations).

chacune des extrémités de leur"allongement" (terme utilisé pour les ailes d'avion) à la périphérie de ces They are fixed at equal spacings, by

each end of their "elongation" (term used for airplane wings) at the periphery of these

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 discs, being arranged so that the perpendiculars (R) to the strings of their profile pass through the axis (0) of the rotor (Figure 4).

 One of the discs (1) comprises a shaft (3) of rotation being perpendicular to it at its center, and the other (1 ') a simple pivot (4) placed in the same way, aligned with the shaft (3). Each of these two elements (3) and (4) pivots in a bearing (5) and (5 ') carried by the frame (6) which holds the whole of the rotor (as does a "carcass" of an electric motor for its armature). This armature can have the most diverse shapes, but minimally impeding the passage of water through the blades. In certain embodiments, the number of blades can be limited to only one (FIG. 2). The discs can be replaced by structures of various shapes (arms, beams, etc., FIGS. 1 and 2) performing the same function of holding the blades (2).

 The blades are immersed in a stream of water perpendicular to the shaft () and, when the rotor turns, the thrusts (F) on each of them generate a motor torque acting on the shaft (3). The latter is most often vertical, and it should be noted that the current can come from any direction without affecting the operation (omnidirectional character).

In some embodiments, as will be seen below, the tree (3) can be horizontal (Figure 10).

 Figure 4 shows the circular path of the centers of thrust (A) of the blades in a plane perpendicular to the axis (0) of the shaft (3) (this center being located about a quarter of the length of the profile rope blade counted from its leading edge).

This profile is generally symmetrical with respect to this rope, but it is not excluded that a slight curvature does not prove beneficial to the performance of the turbine.

 The line (NS) passes through the axis (0), being perpendicular to the water current. Points (A) and (A ')

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 represent two locations of center of thrust, on their circular path, which are symmetrical with respect to the right (NS).

 It will be considered in what follows that the water here is a "perfect fluid", which means that the thrust (F) on each blade is perpendicular to the relative speed (Vr) of the water molecules with respect to the blade .

 The hydrodynamic "drag" being then considered null, only the "lift" is taken into account, and therefore constitutes the force (F).

 The vector (Vr) being the sum of the vector (Va) (speed of the water current) and the vector (v) (linear speed of circular drive of the center of thrust (A) of the blade due to the only rotation of the rotor).

(Vr), puisque les cotés de ces triangles sont perpendiculaires deux à deux. (c'est la seule vitesse (Vr) qui génère la poussée F). Let (B) be the point where the line carrying the vector (F) intersects this line (NS). The triangle (AOB) is similar to that formed by the vectors (Va), (v), and

(Vr), since the sides of these triangles are perpendicular two by two. (it is the only speed (Vr) which generates the thrust F).

OA / v = AB / Vr = OB / Va therefore:
OB = OA x Va / v = R x Va / v (R) being the radius (OA) of the circle traversed by the center of thrust (A) of the blade considered.

 As the Va / v ratio has a constant value, it follows that the point (B) is the same for all the points of the circular path of the blades (the segment OB being a constant). Each force (F), whose representative vector is said here "sliding", can be considered as applied at any point of the line which carries it. The choice of point (B) logically imposes itself for the point of application of the resultant of all these forces (F), because it is common and fixed to them (in perfect fluid).

 When passing through (A) and (A ') (points symmetrical with respect to the straight line NS) of the centers of thrust of the blades, the forces (F) and (F') are scalar equal. They

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are added vectorially to form (F "'), which is always perpendicular to the line (NS). This last force creates a couple C on the shaft (3) being worth:
C = F "'x OB = F"' x Va / vx R
Each point (A) of the semicircle located on the left of the line (NS) has its symmetrical counterpart on the right
The forces (F) and (F ') acting on each of the "pairs" of blades thus determined have their resultant (F "') applied to point (B), which always has the same direction (that of the current of It follows that all the forces (F "') of each of these" couples "never oppose each other (at most, these forces cancel each other out when the blades (N) and (S) pass ).

 The angle (OAB) represents the incidence (i) of the relative current (Vr), which is the only flux to take into account for the creation of the force (F). For the flow to be everywhere laminar it is known that (i) must not exceed approximately 18.

importante que l'incidence maximum (i ) atteinte au cours d'un tour se situe aux environs des points W et E, qui sont les passages frontaux et postérieurs du parcours des pales (en réalité, l'examen attentif de la figure 4 indique que cette incidence maximum se produit un peu au dessous de ces deux points. We can move forward without making mistakes

important that the maximum incidence (i) reached during a revolution is around the points W and E, which are the front and rear passages of the blade path (in reality, the careful examination of figure 4 indicates that this maximum incidence occurs a little below these two points.

pour éviter les"décrochements"et assurer l'"écoulement laminaire"nécessaire aux bons rendements. It is also approximately at these points (E) and (W) that the torque exerted is the greatest, due to the greater incidence (i) combined with an important speed (Vr) of the relative current (which intervenes by its square )
Figure 4 shows that at points E and W tg io = OB / R
If the value of 1/3 is given to the ratio (OB / R), the incidence (i) is worth 18.4; which is very suitable as a limit incidence value not to be exceeded

to avoid "setbacks" and ensure the "laminar flow" necessary for good yields.

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It is therefore possible to conclude that the maximum power that this turbine can collect will be when the order of magnitude of the ratio (v / Va) (circular speed of the blades relative to that of the current) is approximately three.

 It should be noted that the blades thus moving at this relatively modest speed (three times the speed (Va) of the current) probably do not present a danger for the majority of fish (which can swim generally much faster).

"décrochement"progressif, et limitation de la force (F) s'exerçant sur les pales. Les avaries dues à de trop grands efforts s'exerçant sur la turbine peuvent alors être évitées de ce fait.

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Il est possible de simplifier la construction du rotor en supprimant le pivot (4). Les deux paliers (5) et (5') maintenant le rotor sur son armature (6) sont alors disposés sur le seul arbre (3). Le disque (1') lui-même (ou la structure (1") en tenant lieu) peut être également supprimé ; ce qui a cependant alors l'inconvénient de diminuer la cohésion des pales entre elles. If the speed of rotation is imposed (for example, as will be seen below, by the period of the connected alternating electrical network), and the current (Va) exceeds the optimum value provided, there is

progressive "drop", and limitation of the force (F) exerted on the blades. Damage due to excessive forces exerted on the turbine can then be avoided because of this.

1
It is possible to simplify the construction of the rotor by removing the pivot (4). The two bearings (5) and (5 ') holding the rotor on its frame (6) are then placed on the single shaft (3). The disc (1 ') itself (or the structure (1 ") taking the place of it) can also be omitted; which however has the disadvantage of reducing the cohesion of the blades between them.

 It is interesting that these discs have a lenticular section for better penetration into the water stream. It can be expected that their face facing the blades is sufficiently curved so that the flow is accelerated by the narrowing of its passage between them, which can only increase the energy collected.

 The armature (6) of the rotor can be fixed under the hull of a floating machine (7), either directly, or by means of more or less long spacers to arrange it at the desired depth. This machine can

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être une bouées, un corps-mort, une bare, ou tout autre structure flottante, qui est amarré à une berge, ou au mouillage (plusieurs lignes de mouillage sont alors conseillées)
L'arbre (3) en pénétre ses fonds par un presse- étoupe ou joint-spi pour être connecté aux appareils récepteurs de l'énergie recueillie par la turbine, qui sont alors situés en milieu sec.

be a buoy, a mooring, a bare, or any other floating structure, which is moored to a bank, or at anchor (several mooring lines are then recommended)
The shaft (3) penetrates its bottoms by a cable gland or gasket to be connected to the devices receiving the energy collected by the turbine, which are then located in a dry environment.

 It can also lead into a well, or pass between two hulls of a multihull floating machine, saving the stuffing box or oil seal. The two bearings (5) and (5 ') can thus not be submerged to avoid corrosion; but they must then, like the tree (3), be very robust because of the very large overhang that they support.

 It is even interesting in this case to slightly protrude the blades out of the water to reduce the viscous friction of the disc (1) or of the structure which takes place (the blades are then the only rotating elements which are immersed when the lower disc (1 ') is deleted).

 In a watercourse, such floating devices can be integrated into the landscape without distorting it, especially if they are "camouflaged" in fishing boats or in traditional barges.

 At sea, a single mooring line may possibly suffice, but it would be advisable to have several to better immobilize the floating object, and thus prevent twisting of the electric cables which transport the energy supplied by the turbine.

 Contrary to the above, the frame (6) of the turbine can be fixed on a massive base anchored to the bottom of the water, the structure of which is studied to arrange it at the desired height (shaft (3) always kept vertical) .

 This tree can exceed the surface of the water to be coupled to energy receiving devices

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 produced (Figure 7). On the contrary, it can lead to a sealed enclosure, where these devices are housed (in this case, they are electrical generators), passing through a cable gland or joint spy. This sealed enclosure can be located above the turbine but it will most often be below (Figures 5 and 6), being attached to the base or housed therein. The cables carrying electrical energy are buried under the water bottom or simply rest on it.

 As has already been said, the omnidirectional nature of the turbine makes it possible to ignore the direction of the current, which are often "turning" during the tides.

 The operation of the turbine differs depending on whether the generator is coupled to a large alternative electricity network whose period is well established, or whether it is a question of supplying energy to an isolated place, in quantity, modest.

 In the first case, the shaft (3) is connected to an alternator, in general by means of a speed multiplier (direct coupling is possible, in particular by recent techniques). Therefore the rotational speed of the rotor is then constant.

 In the second case, the shaft (3) is connected to a direct current generator or to an apparatus directly using the mechanical energy it provides (grinding wheels, saws, etc.). The speed of rotation can be this time a function of that of the current.

 The mechanical and electrical characteristics of the installation should be carefully chosen according to the variations in the speeds of the water currents to be expected (it has been seen above that the order of magnitude of the ratio between peripheral speed (v) of blades and speed (Va) of the current is three, but this figure must be refined by effective tests).

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It should be noted that at sea the speeds of tidal currents are well determined in advance without fear of possible devastating floods.

 Whether offshore or in watercourses, a choice will have to be made between turbines installed on floating machines (anchored, or moored on banks or dolphins), and those secured to bases placed on the bottom . The first alternative allows easy access to the generators, but subjects the installation to the vagaries of the weather; the second requires a tight compartment for a difficult approach.

 The option “large alternative network-constant speed of rotation” also makes it possible to solve the starting difficulties which this turbine can present. The alternator then behaves temporarily as a synchronous motor (a well-known conventional assembly in electricity allowing the starting of such a motor).

 It is also possible in this option to replace the alternator with a generator constructed as an asynchronous motor. It has indeed been observed (with astonishment the first time, because it was not provided for, on mine wagons) that such a motor behaves as an auxiliary AC generator when it is connected to a general network. important which is already under AC voltage for a given period. However, it is quite possible that the yield will not be excellent. This arrangement has the interesting feature of allowing various rotational speeds which can better adapt to fluctuations in the water current.

 These rotational speeds are also variable when direct current generators are used.

The latter can be used as is, for example

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 for small specific direct current installations in an isolated place, or transformed into alternating current by an inverter.

 This turbine can also be used to supply energy to devices intended to raise the temperature of a water circuit for space heating (by FOUCAUD currents for example), or to actuate grinding wheels, or various mechanisms.

 The shaft (3) of this turbine can also be arranged horizontally. This is the case when it completely or partially bars a channel (Figure 10) which channels the current between two approximately or exactly vertical walls (which then play together, with the ground, the role of the armature (6) of the rotor. ). One of the walls carrying the bearing (5 ') of the pivot (4), and the other the bearing (5) of the shaft (3). The latter also passing through a cable gland or joint spy to lead into a dry compartment where it is connected to devices collecting the energy captured by the turbine.

 It is possible to facilitate starting. and to improve the operation of these turbines by equipping them with blades, part of which is made of flexible and elastic materials; the other remaining rigid.

 The limit between these two adjoining parts, rigid and elastic, is located approximately in a plane perpendicular to the chord of the profiles, being located a short distance from the leading edge and parallel to it.

Only the part including this leading edge is rigid and is fixed by each of its two ends to the two discs (1) and (1 ') of which it ensures mutual cohesion (by playing the role of the bars of the "cage of squirrel "in figure (3) already cited).

 The other part, linked to the first and extending to its trailing edge, consists of

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 flexible and elastic materials. The complete blade regaining its original profile when the water flow is zero; whether the rotor is stopped or rotating.

 We can achieve a fairly close elastic effect while retaining the blades their total rigidity. Each of them must then be provided with a long pivot which crosses it longitudinally, perpendicular to its profile, very close and at a constant distance from its leading edge. These pivots are fixed by their two ends to the discs (1) and (1 '), and thus exactly constitute the bars of the "squirrel cage" previously mentioned).

 Each blade can pivot around its pivot, but various silentblocs or springs (spiral springs or simple elastic blades) are interposed between these two elements by connecting them. They are also reciprocally "set" so that the blade remains perpendicular to the radius (R) which concerns it (like the initial blades not benefiting from this elasticity) when the current is zero (whether the rotor is rotating or not).

 A simple careful examination of FIG. 4 makes it clear that at points (W) and (E) for example, 'these elastic devices determine when the blades are deflected, the orientation of the blades is deflected under the effect of force (F ) due to the current (Va). This deviation determines an inflection of this force (F) which creates starting torques of the same direction in (E) and (W)).

 (when the turbine is not fitted with these elastic devices, and it is stopped, all the forces F exerted on the blades pass approximately through the center (0) of the rotor. The starting torque is therefore practically zero. It is then essential to apply momentarily an external engine torque acting on its shaft (3); as has been seen above for the generators operating momentarily in motors supplied by the network.

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electric outdoor).
In addition to this effect favoring starting, this elasticity determines a lesser increase in the incidence (i) when, in normal operation, the current (Va) accelerates. This delays the moment of the "unhooking" of the water streams, thus contributing to the operating stability of the device.

 It is difficult to predict in advance whether the turbine presented here will have a greater development for the exploitation of watercourses than for that of marine currents.

 It is this second alternative which is chosen as an embodiment in the following. In this perspective, it is possible to envisage supplying electric current to an isolated place, by the sea. One or more turbines can be placed in a pass leading to a body of water; or off a coast where the currents are strong.

 More ambitious is the supplementary supply of a large alternative electrical network by the establishment of a veritable "field of turbines", also placed offshore or in a pass, in a place where the tidal currents are very strong. (BREAST RESET for example).

 These will have their heavy base placed on a flat bottom (so that the shaft (3) is roughly vertical). Concrete elements, or made of metal beams, carrying the two bearings (5) and (5 '), will be fixed on it to keep the turbine at the right height.

 An alternator will be housed in a watertight compartment linked to the base. This tightness, both for the passage of the shaft (3) as for the electric cables and the inspection doors, must be

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 particularly neat.

 The turbine will be started by the general electrical network (by conventional means, as has been said, used for starting synchronous motors). The turbine will continue to rotate always at the same constant speed determined by the period of the network, even during tidal stalls, with a low energy taken from the network.

 To save this energy, it could however be envisaged to let the turbine stop by itself, by isolating it from the network during these periods of stalls. The restart is carried out as described above.

 Such an installation will be entirely sheltered from storms and will not fear excessive current speeds, since these depend only on the tidal coefficients (which also makes it possible to predict production rates well in advance. electricity and start up the auxiliary heat generators in time).

 In addition, on the same coast, the tide times are spread over time, which tends to equalize energy production.

Claims (10)

 1 / Turbine having the configuration of a rotor forming a "squirrel cage" consisting of two parallel discs (1) and (1 ') and of "bars" which join them, the latter being in reality in the form of blades (2) identical elongates, profiled in airplane wings (FIG. 3), or thin planes taking the place thereof, which are fixed by the ends of their elongation to the periphery of these discs, one (1) of the latter comprising, perpendicularly to it and at its center, a drive shaft (3), the other disc (1 ') being provided with a single pivot (4) oriented in alignment with the shaft (3), these last two elements being maintained each by a bearing (5) and (5 ') allowing their rotation arranged on a support frame (6) of the rotor, characterized in that these blades (2) are immersed in a stream of water perpendicular to the rotor drive shaft (3) being oriented on the discs so that the perpendiculars (R) to the co rdes of their profile lowered approximately from their center of thrust (A) pass through the axis (0) so that the thrusts (F) exerted on the blades (2) by the current of water during the rotation of the rotor generates a motor torque applied to the shaft (3), the discs (1) and (1 ') can be replaced by structures (1 ") of various shapes performing the same functions and the number of blades (2) possibly being limited to one.  2 / Device according to claim 1 for a simplification of construction characterized by the removal of the disc (1 ') or the structure (1 ") by acting, or simply by the removal of its pivot (4), the aligned bearings (5) and (5 ') arranged <Desc / Clms Page number 14>  on the frame (6) then both maintain the shaft (3) remaining.  3 / Device according to claims 1 and 2 characterized in that the discs (1) and (1 ') have a section of lenticular or semi-lenticular shape for better penetration in water, their side facing the blades (2 ) can be sufficiently bnmhées so that the flow is accelerated by the narrowing of its passage between them.  4 / Device according to any one of the preceding claims, characterized in that the armature (6) of the rotor is integral with a floating body (7) moored to a bank or anchored, the shaft (3) kept vertical passing through its bottom by a cable gland or joint-spy to be connected to the apparatuses receivers of the energy taken from the current of water, it can also pass in a well or between two hulls if the floating body is a multihull, in the latter case it can be provided that the upper part of the blades (2) is not immersed in order to remove the viscous friction of the disc (1), or of the structure (! ") 'replacing them, and to reduce the corrosion of the bearings ( 5).  5 /. Device according to claims 1, 2,3, characterized in that the lower part of the frame (6) is secured with a solid base solidly fixed to the bottom of the sea or of a watercourse, which holds the turbine at the desired height above the bottom, the shaft (3) kept vertical which can exceed the surface to be coupled in the open air to the generators provided to collect energy or lead after passage through a cable gland or seal-spy in a submerged sealed enclosure containing these generators, which may be located above the rotor, or below inside the base. <Desc / Clms Page number 15>  6 / Device according to any one of the preceding claims, characterized in that the shaft (3) has a variable speed of rotation depending mainly on the force of the current, by being connected directly or by means of a speed multiplier of rotation to an eddy current heat generator which heats the water of a hydraulic heating circuit, or to a conventional generator of direct electric current, or to a generator constituted as an asynchronous motor to supply energy d '' Addition to an alternative general network vessel of established period.  7 / Device according to any one of claims 1 to 5 characterized in that the shaft (3) is connected directly or via a rotational speed multiplier to an alternator which supplies energy from back-up to a general alternative electricity network with an established period which therefore imposes on it a constant speed of rotation, this network also providing the energy necessary for starting this alternator by one of the conventional electrical arrangements used to start synchronous motors .  8 Device according to any one of claims 1 to 3 and 6 and 7, characterized in that the axis (0) of the rotor is disposed horizontally between two approximately vertical walls channeling the stream of water, the pivot (4) being maintained by its bearing (5 ') fixed on one of the walls, while the shaft (3) has its bearing (5) fixed on the other wall which it passes through by a cable gland or oil seal enter a dry compartment where it is connected to the devices it drives, the entire floor and walls acting as the support frame (6). <Desc / Clms Page number 16>

9 / Device according to any one of the preceding claims to facilitate the start of the rotation of the rotor and improve its operation. characterized in that only the part of the blade (2) close to its leading edge is rigid and fixed by its two ends to the discs (1) and (1 '), its other part which completes it up to its edge of leakage, consists of flexible and elastic materials which are not secured to the discs (1) and (1 '), the blade (2) keeping a classic shape and an orientation perpendicular to the radius (R) which concerns it when the water current is zero but exhibiting a variation in curvature and a deviation of this orientation under the effect of the thrusts (F) when this is no longer the case.  10 / Device according to any one of claims 1 to 8 to facilitate the start of the rotation of the rotor and improve its efficiency, characterized in that each blade (2) is traversed entirely

 longitudinally at a constant constant distance from its leading edge by a pivot parallel to the shaft (3), which maintains it and guides its pivoting on itself, and whose ends are fixed on the periphery of the discs (1) and (1 '); silent blocks, elastic blades or spiral springs are interposed between each pivot and its blade (2) to limit their reciprocal angular displacement which occurs due to their elasticity under the effect of the thrust due to the current of water, these latter elements are in addition arranged and wedged so that the profile chord of the blades (2) remains perpendicular to the radius (R) when the current of water is zero.