DE202009010904U1 - Hydrofoils for watercraft - Google Patents

Abstract

Wing (100), in particular rudder, for watercraft, in particular ships, with an end strip (20), characterized in that at least one projection body (30) for reducing the vortex formation on the end strip (20) is arranged.

Description

The Invention relates to a wing, in particular a rudder, for Watercraft, in particular ships, with an end strip.

Wings are used in the present context in watercraft or built-in body, in fluid mechanics Create visibility lift. Examples of hydrofoils are rudders, keels, hydrofoils in hydrofoils, Stabilizer fins or other fin-like body of Watercraft. The wing according to the invention is in particular used suitable as a rudder, whereby the use as one of the aforementioned body or another wing-like body readily possible is.

Known Hydrofoil normally have one associated with a flow direction or in Nautical direction aligned noseband and one of these opposite End bar on. Between the leading edge and the end strip are side surfaces resp. Side walls of the wing arranged. The upper end of the wing is usually solid rotatable in the case of a rudder, connected to the vessel body, whereas the opposite lower end is normally formed as a free end. With oars However, it is also known that these are also stored at the bottom could be (for example, with rudders stored in the sole).

The wing body is flowed around in use in a watercraft by the water in the direction of the leading edge of the leading edge. Depending on the Reynolds number, the flow or the flow velocity and the geometric shape of the wing or the end bar of the wing may come behind the wing or at the end bar to vortex shedding in the flow direction, whose frequency is characterized by the Strouhal number. The vortexes often arise on either side of the body around which they are flowing, their directions of rotation being opposite to one another. The flow between them runs in the direction of the body around which flows in the opposite direction to the outer flow. This drag-like vortex system, consisting of opposing vortices that form on the body around which it flows, is driven away by the flow and finally dissipated, is also known as the Kármán vortex street. This phenomenon is particularly noticeable in oars, as they are exposed to the relatively fast propeller flow of a marine propeller. Furthermore, such rudders in particular tend to form Karmann vortex streets which have a relatively wide end bar. These are in particular rudder with a fishtail or Schilling ^® profile in which the end portion of the rudder blade in the flow direction viewed towards the trailing edge, in particular dovetail-like, broadened. In such geometries, the Strouhal number and thus the separation frequency of the individual vortices is particularly high, whereby Kármán-vortex streets can arise or are particularly pronounced.

4 shows the formation of a Kármán vortex street in a known from the prior art wing 200 , The wing 200 from the 4 is a fishtail rudder, where the cross-sectional profile to the end bar 201 widened again. For the sake of clarity, only the end of the wing 200 shown. The end bar 201 runs concave between the two end regions 2021a . 2021b the side surfaces 202a . 202b , The course of the (propeller) flow is represented by a multitude of arrows. It can be seen that the flow is essentially laminar on the side surfaces 202a . 202b runs along. Does the flow pass the end regions? 2021a . 2021b the side surfaces 202a . 202b , dissolve in both the top of the end bar 201 as well as in its lower part vortex 210 from the flow. At the top of the end bar 201 or directly behind the side surface end point 2021a has a counterclockwise rotating vortex 210 educated. In the flow direction obliquely below is another, counter-clockwise, namely rotating clockwise vortex 210b present, located on the lower side surface 202b or directly behind it. Downstream is another counter-clockwise rotating, slowly dissipating vortex 210c present, also from the upper side surface 202a comes. The vortex 210a . 210b . 210c together form the vortex system of the so-called Kármán vortex street. In the area of the vortexes or between the vertebrae, the pressure drops significantly in relation to the flow surrounding the Kármánsche vortex street.

By the training of the Kármán vortex streets becomes on the one hand reduces the efficiency of a wing or in the case from rowing reduces the rudder power. Also increases the wing or Rudder drag. On the other hand, the lateral force of a rudder is reduced and it can cause vibrations on the wing. The latter is particular the case when the detachment frequency the vortex corresponds substantially to the natural frequency of the wing body.

Therefore It is an object of the present invention to provide a wing, in which the negative effects of vortex formation in the flow direction behind the wing or the Kármán vortex streets reduced become.

The solution This object is achieved with a wing with the features of the claim 1.

core idea the invention is to provide a projection body on the end strip, by which the vortex formation is reduced. A protrusion body is in the present context a basically arbitrarily designed Body, that of the end rail of the wing protrudes or protrudes. Because the end bar is usually in one Cross-sectional view essentially transversely to the wing longitudinal direction runs, is the protrusion body in general, at least roughly, in the downstream direction.

The Endleiste is usually a wing final surface, the be rectilinear, concave, convex or otherwise running can. The protrusion body is now from this area before, which leads to that reduces the likelihood of detachment of a vertebra becomes. As a result, the probability of the occurrence of a Kármán vortex street reduced become. The effectiveness of the at least one projection body depends on various factors, such as the number of projection body, the geometric Design, as well as the exact arrangement.

at the at least one projection body is it a body which in itself does not belong to Endleistenfläche, but arranged at this is and projects from this. A projection body is in this sense so no slight bulge out of the end bar surface z. B. convex Endleiste o. The like., But a substantially independent body, the however expediently is firmly connected to the end bar or the Endleistenfläche. Accordingly the protrusion body For example, be made of metal, especially steel and by welding or other suitable attachment methods or means with be connected to the end bar. By projecting a body out of the Endleistenfläche In particular, it is avoided that on both sides of the Wing opposing vortex pairs form the requirement for are the training of a Kármán vortex street.

By the providence of the at least one projection body becomes the probability the occurrence of a Kármán vortex street at a Hydrofoil reduces and thereby the wing resistance and thus also improves fuel efficiency. Furthermore there is a risk of damage of the wing or the vessel body reduced by vibrations. Since the at least one projection body to the end bar is arranged, this also does not reduce the effective inflow of the wing and, being outside himself the inflow surface and thus outside the mainstream is located, do not trigger cavitations by a separation of the flow. Accordingly through the providence of a flow body through a relatively small construction effort and without a weakening of the Cross-section of the actual wing in fluidic terms the beneficial effect of reducing vortex formation in the area the end bar can be reached. By the invention at least a projection body the process of vortex formation is disturbed or impeded, whereby a much more stable or laminar flow pattern in the flow direction behind the wing considered arises.

In With respect to the width of the end bar, the at least one projection body is expediently designed so that it does not cover the entire width. Much more he jumps advantageously only from a section in relation to the end bar width. This will ensure that a blockage of the vortex flow is achieved. Would the at least one projection body covering the entire width of the end bar, the protrusion body could fluidically as a pure extension of the wing act and the unwanted, opposing Detach the vertebrae on both sides of the projection body.

preferred embodiments The invention are characterized in the subclaims.

Around one possible To achieve substantial reduction of vortex formation, it is in a preferred embodiment the invention provides that the at least one projection body over at least 50% of the length the end strip, preferably at least 75%, more preferably substantially above the overall length the end bar runs. By the term "length of the Endleiste "is in the present context, the distance between upper and lower End of the wing Understand the end bar. The end bar usually runs over the entire height of the wing. Therefore, it is appropriate that the at least one projection body over a the largest possible area the end bar runs, so in terms of height of the wing preferably widely the Vortex formation is reduced or disturbed. Especially useful the course of the at least one projection body from a Endleistenende to other, because thus a disturbance the vortex formation over the entire height of the wing is ensured. The at least one projection body can expediently from a single body exist, whose length the length of the End bar corresponds and is attached to the end bar. Basically, it would be also possible, in that the at least one projection body is composed of a plurality of partial bodies.

Basically the at least one projection body designed to run arbitrarily with respect to a cross-sectional view be. Often it will, however, be appropriate in a cross-sectional view of the wing, the at least one projection body in the Substantially parallel to a centerline of the wing or runs along the midline. In this respect runs the at least one projection body preferably straight in cross-section. In appropriate tests It has been shown that by such an orientation of at least a boss body a particularly good disorder the vortex formation or a particularly favorable flow pattern can be achieved. In particular, at least arranged along the center line a projection body will be a particularly even disorder of the Vortex formation on both sides of the wing achieved. If several projection body are provided, preferably all projection bodies are parallel designed to run to the center line. However, it is also possible that individual projection bodies differ from this orientation. This can in particular with arcuate or be displayed with concave or convex end bar. at the present embodiment refers to the flow of the at least one projection body in the cross-sectional view on the course between endleistenseitigem and free end of the at least one projection body.

Further it is preferred that the at least one projection body in Essentially parallel to the longitudinal axis of the wing runs. The longitudinal axis is the axis that from the upper wing end to the lower wing end runs. Rowing becomes the longitudinal axis often also be the rudder axis. Also, the at least one projection body in Essentially parallel to the outer edges the end bar run. The outer edges of the End bar will be common also parallel to the longitudinal axis of the wing be aligned. This results in a uniform flow pattern. In particular, it is preferable for the at least one projection body to be parallel to the longitudinal axis and over the entire length the end bar runs. This results in a particularly even flow pattern.

In a further preferred embodiment the invention jumps the at least one projection body in Essentially perpendicular or orthogonal to the surface of the End bar in front. The right angle is between the end bar and the axis along the width of the wing (transverse axis) is formed. Is the end bar surface also, in the case of a plurality of protrusion bodies, the protrusion bodies are corresponding arranged parallel to each other. This will be the evenness the flow in the flow direction behind the wing further improved.

preferably, corresponds to the width of the projection body, d. H. his distance between end bar and its free end, at least half the width of the end bar. Tests have shown that at such dimensions of at least a boss body particularly good results the reduction of vortex formation can be achieved.

are at least two projection bodies provided it is appropriate, the two projection bodies spaced from one another and / or parallel to each other to arrange. By the spaced arrangement of the at least two projection body is the vortex formation difficult more difficult, since now two independently projecting Objects the vortex flow To block. Improves the parallel alignment of the two projection body again the regularity of the flow pattern.

In a further preferred embodiment the formula: number of protrusion bodies = 2n + 1, where "n" is a natural number, including 0, is. Particularly preferred is n = 2, d. H. the number of protrusion bodies is 5. Further, in a cross-sectional view, one of the protrusion bodies is substantially centered on the end bar and an even number of protrusion bodies arranged on each side of the centrally arranged projection body. Particularly preferred results in a symmetrical arrangement, wherein the center line of the wing in the cross-sectional view expediently the symmetry line forms. Advantageously, the individual projection bodies are spaced apart arranged mutually and / or parallel to each other. Testing have revealed that by such, evenly distributed and in particular symmetrical design, in particular with 5 projection bodies, a particularly good effect in terms of reducing vortex formation established. Further, in this embodiment, it is preferable that the centrally arranged projection body the largest width, d. h., the largest distance has between end bar and free end. If necessary, too two of the same size Ribs can be arranged in a central region. Furthermore can the width of the other projection body advantageously after Outside steadily decrease, leaving the outermost projection body have the smallest width. Appropriately, this is also here the training provided symmetrically, d. h., the mirror image have arranged protruding body pairs each have a same width. This is from the outside to inside a gradual blocking of the vortex flow achieved.

If several projection bodies are provided the distances fundamentally different between the individual projection bodies be the same. Which arrangement aerodynamically most favorable is, hangs in each case from the circumstances the individual case, in particular the geometry and width of the end bar, the flow velocity, the exact formation of the projection body, etc., from.

Especially Preferably, the at least one projection body is plate-shaped or as projecting from the end rib, trained. The rib is expediently from a plate, for example a steel plate o. The like., The attached to the end bar with one end face. Is the plate elongated, especially about a large part or over the entirety of the length the end strip running formed, is the rib or plate preferably with a longitudinal end face to arrange or attach to the end bar. In such a training results in a strip-shaped Arrangement of the rib. If several ribs are provided, it is appropriate, this parallel to each other and to arrange parallel to the longitudinal axis of the wing. Instead of as a plate could the ribs also slightly rounded in their free end area or be rejuvenating to its free end o. The like. Be formed.

Particularly useful at least one projection body is provided formed wings in a ^® as a fishtail or Schilling rudders, in which the profile in a cross-sectional view of one of the trailing edge towards oppositely disposed leading edge toward the trailing edge to a central region, wherein the widest Site of the airfoil profile, widened, from the central region to a rear area, which forms the narrowest point of the airfoil, tapered and widened from the rear to the end bar, in particular dovetailed again, the end bar preferably rectilinear, convex or concave is trained. Due to the relative width of the end bar in comparison to other airfoil profiles, vortex formation is particularly frequent in the airfoil profiles described above. In this respect, the provision of the at least one projection body in such profiles is particularly expedient.

below The invention is explained in detail in the drawing with reference to various embodiments. It show schematically:

1 a perspective view of a wing with end bar and projection bodies,

1A a detailed view of the upper end portion of the end bar of the wing from the 1 .

2A - 2E Top views of end portions of airfoils with differently shaped end strips and differently arranged or formed projection body (s),

3 a plan view of the end portion of a wing with protruding from the end bar projection bodies with drawn flow path, and

4 an end portion of a wing from the prior art with marked flow path.

at the various embodiments described below the invention are the same components provided with the same reference numerals.

1 shows a perspective view of an airfoil 100 , In the present case, the wing 100 formed by a rudder with Fishtail or Schilling ^® profile. The rudder includes a leading edge 10 as well as an end bar 20 , Between the leading edge 10 and end bar 20 the side surface runs 11 , At the upper end 12 as well as at the bottom 13 of the wing 100 is each a graduation sheet 14 intended. As it is the present wing 100 is a rudder with fishtail profile, widens the end 15 of the rudder of a rear area forming the narrowest point of the rudder 16 to the end bar 20 ,

At the end bar 20 are a total of five formed as a plate-shaped ribs protrusion body 30 provided, each from an upper end 12 to the bottom 13 run and are arranged parallel to each other.

As seen from the detail view 1A recognizable, the middle rib points 30a the largest width. On both sides of the middle rib 30a There are two more ribs each 30b . 30c arranged, wherein the width of these ribs decreases towards the outside. The plate-shaped ribs 30a . 30b . 30c are with their longitudinal end faces on the end bar 20 , which is rectilinear or formed as a flat surface attached. Likewise, the ribs lie 30a . 30b . 30c with their transverse faces on the end plates 14 and are attached to this as well. The outer ribs 30c have the shortest width and are opposite the outer edge 21 the end bar 20 only slightly offset inwards. The plate-shaped ribs 30a . 30b . 30c are each substantially perpendicular from the Endleistenfläche and parallel to the outer edge 21 the end bar 20 or to the longitudinal axis of the wing 100 ,

2A shows a plan view of the Endbe rich 15 of the wing from the 1 , It can be seen that the middle of the rib 30a the largest width b1 and the outer ribs 30c have the smallest width b3, whereas those between the ribs 30a and 30c arranged ribs 30b have a mean width b2. Further, the distances between the ribs 30c and 30b (a2) and the ribs 30b and 30a (a1) different, wherein the distance a1 is greater than a2. The exact dimensioning of the widths and distances can each have an optimal vortex reduction effect with respect to the respective geometry of the end bar or the ribs 30 be matched. The rib 30a runs along the midline 17 whereas the ribs 30b and 30c parallel to the midline 17 run. The midline 17 also forms the symmetry axis for the rib arrangement.

The 2 B to 2E show further examples of embodiments of the end 15 of hydrofoils according to the invention 100 , So is the case 2 B a central, along the midline 17 arranged rib 30a intended. Furthermore, two further, each arranged on the outside and the same width ribs 30c intended. Ribs 30c are in relation to the midline 17 arranged symmetrically. In the three-rib training from the 2 B is the end bar 20 formed concave in a plan view and cross-sectional view. In the 2C is the end bar 20 however rectilinearly formed, or the end bar 20 forms a flat surface. Furthermore, there is only a single rib 30a provided along the midline 17 is arranged. In the 2D is the end bar 20 in a plan view and cross-sectional view, similar to the 2 B , concave running formed. Also are a middle rib 30a that go along the midline 17 runs, as well as two outer ribs 30c intended. Unlike the 2 B in which all three ribs are aligned in parallel, as well as in the 2A , are the two outer ribs 30c not parallel to the midline 17 or to the middle rib 30a trained, but run at an angle to it. In particular, they run away from the inside in the direction of the end bar. In the 2E Also, five ribs are provided, with the end bar 20 is formed convex in a plan view and cross-sectional view. The middle rib 30a , which again has the largest width, runs along the center line 17 , The two outer ribs 30c have the smallest width. The right and left of the center line 17 arranged ribs 30b . 30c are along the center line 17 arranged symmetrically to each other. In contrast to the representation from the 2A are the ribs 30b and 30c not parallel to the midline 17 or to the rib 30a arranged, but each stand at an angle of about 90 ° from the convex shaped end bar 20 off, leaving from the end bar 20 to the free end of the ribs 30a . 30b . 30c considered outwardly forming an arrangement of the ribs.

All in the 2A to 2E shown ribs 30a . 30b . 30c are formed as plates.

3 shows a plan view of an end region 15 an airfoil according to the invention 100 , The end bar 20 is formed in a straight plan view or cross-sectional view. The five of the final bar 20 protruding ribs 30a . 30b . 30c are essentially made according to the arrangement 2A arranged and formed, wherein in the illustration shown in FIG 3 Unlike 2A the distance between the ribs 30c and 30b is larger than the one between the ribs 30b and 30a , The flow pattern is represented by the plurality of arrows. Thus, with the invention wing formation in the area of the side walls 11 downstream from the wing 100 a substantially laminar flow pattern. Between the upper rib 30b and the middle rib 30a a vortex forms 40 which is formed turning in a counterclockwise direction. In addition, it can be seen how the vortex formation in the spaces between the individual ribs due to the blocking by the ribs 30a . 30b . 30c can not take place. In the direction of flow already short of the vortex 40 turns on the entire width of the wing 100 a laminar flow pattern. Furthermore, only a single vortex 40 thus suppressing the formation of a Kármán vortex street, each formed by pairs of counter-rotating vertebrae.

LIST OF REFERENCE NUMBERS

100

Hydrofoil

10

leading edge

11

side surface

12

upper The End

13

lower The End

14

closing panel

15

end

16

rear Area

17

center line

20

end strip

21

outer edge

200

Wing (Stand of the technique)

201

end strip

202a, 202b

faces

2021a, 2021b

Side face endpoints

210

whirl

30

projection body

40

whirl

Claims (14)

Wing ( 100 ), in particular oars, for watercraft, in particular ships, with an end bar ( 20 ), characterized in that at least one projection body ( 30 ) to reduce vortex formation on the end strip ( 20 ) is arranged. Wing according to claim 1, characterized in that the at least one projection body ( 30 ) over at least 50% of the length of the end bar ( 20 ), preferably over at least 75%, more preferably substantially over the entire length of the end strip ( 20 ), runs. Wing according to claim 1 or 2, characterized in that in a cross-sectional view of the wing ( 100 ) the at least one projection body ( 30 ) substantially parallel to a center line ( 17 ) of the wing ( 100 ) or along the midline ( 17 ) runs. Wing according to one of the preceding claims, characterized in that the at least one projection body ( 30 ) substantially parallel to the longitudinal axis of the wing ( 100 ) runs. Wing according to one of the preceding claims, characterized in that the at least one projection body ( 30 ) substantially orthogonal to the surface of the end strip ( 20 ). Airfoil according to one of the preceding claims, characterized in that the width of the projection body ( 30 ) at least half the width of the end bar ( 20 ) corresponds. Airfoil according to one of the preceding claims, characterized in that at least two projection bodies ( 30 ) are provided, wherein the projection body ( 30 ) are spaced and / or arranged parallel to each other. Wing according to one of the preceding claims, characterized in that the number of projection bodies ( 30 ) 2n + 1, in particular 5, and in a cross-sectional view a projection body ( 30a ) substantially in the middle of the end bar ( 20 ) is arranged and an even number of projection bodies ( 30b . 30c ) to each side of the centrally arranged projection body ( 30a ), in particular symmetrically, are arranged. Wing according to claim 8, characterized in that the centrally arranged projection body ( 30a ) has the greatest width and possibly the width of the other projection body ( 30b . 30c ) continuously decreases towards the outside. Airfoil according to one of the preceding claims, characterized in that a number of projection bodies ( 30 ) is provided, wherein the distances between the individual projection bodies ( 30 ) are the same or different. Wing according to one of the preceding claims, characterized in that the at least one projection body ( 30 ) plate-shaped and / or as from the end bar ( 20 ) projecting rib, is formed. Wing according to one of the preceding claims, characterized in that the profile of the wing ( 100 ) in a cross-sectional view of one of the end bar ( 20 ) arranged opposite nose strip ( 10 ) in the direction of the end bar ( 20 ) to a central area, which forms the widest point of the airfoil profile, widened, from the central area to a rear area ( 16 ), which forms the narrowest point of the airfoil profile, tapers, and from the rear area ( 16 ) to the end bar ( 20 ), in particular dovetailed, widened again. Wing according to claim 12, characterized in that the end strip ( 20 ) is rectilinear, convex or concave. Vessel, in particular a ship, characterized in that it has a wing ( 100 ) according to one of the preceding claims.