KR101494107B1 - A hydrofoil for water-borne vessels - Google Patents

Abstract

In order to provide a hydrofoil 100 for a waterborne marine vessel 100, in particular a rudder, which has an adverse effect of vortex formation from the rear of the hydrofoil in the flow direction and / or a detrimental effect of the Kaman vorticity street, (20) to reduce the amount of heat.

Description

{A HYDROFOIL FOR WATER-BORNE VESSELS}

The present invention relates to a hydrofoil and relates to a marine vessel having a trailing edge, in particular marine rudders.

Current hydrofoils are bodies that are used and / or installed in marine vessels that generate lifts from a hydrodynamic perspective. Examples of hydrofoils include a rudder, a keel, a hydrofoil skid on a hydrofoil boat, a pinned form of a stabilizer fin or other marine vessel. The hydrofoil according to the present invention is particularly stable for use in a rudder and may be used as one of the bodies of the above-described bodies and / or other hydrofoil-shaped bodies.

The hydrofoil of the prior art typically has a leading edge assigned to the direction of flow and / or aligned in the direction of movement of the watercraft, and a trailing edge that confronts the leading edge. The side or side wall of the hydrofoil is disposed between the leading edge and the trailing edge. The upper end region of the hydrofoil is typically rigidly connected to the hull of the watercraft, i. E. In the case of a rudder, so that the lower end of the hydrofoil is normally designed as a free end. However, in the case of a rudder, they are known to be supported at the lower end (for example, in the case of a rudder supported by a single member).

When used in watercraft, water flows from the leading edge to the trailing edge around the body of the hydrofoil. Depending on the flow rate and geometry of the Reynolds number and the hydrofoil or hydrofoil trailing edge, vortex separation occurs at the rear of the hydrofoil, in the trailing direction, in the flow direction, and the frequency is characterized by the Strouhal number. Vortices are typically generated on both sides of the body in which the fluid flows around and whose directions of rotation are opposite to each other. The flow between them flows in a direction toward the body where the fluid flows around and is opposite to the outer flow. This vortex system in the form of a wake of vortices in the opposite rotational direction forming a body that flows around and is driven far and finally diffused by the flow is known to be called the Karman vortex street. This phenomenon occurs especially in the case of rudders, because they are exposed to the very fast flow of ship propellers. Moreover, a rudder with a particularly large trailing edge has a tendency to generate a Kamman swirl stream. These are rudders with a fish tail shape or a Schilling® shape, especially when viewed in the direction of flow, in which the end area of the rudder blade widens towards the trailing edge, especially in the dovetail form. In this kind of geometry, the stolen number and the separation frequency of each vortex are very high, and consequently, especially the Kaman vortex street can be generated and / or present in a unique form.

Figure 4 illustrates the formation of the Kamandrau streets of the hydrofoil 200 of the prior art. 4, the hydrofoil 200 is a fish tail-like rudder, and its cross-sectional shape is widened toward the trailing edge 201. For the sake of clarity, only the end region of the hydrofoil 200 is shown. The trailing edge 201 is formed in a concave manner between the two end regions 2021a, 2021b of the side surfaces 202a, 202b. The pattern of the propeller flow is shown by numerous arrows. It can be seen that the flow basically flows along the side surfaces 202a and 202b in a laminar flow manner. As the flow passes through the end regions 2021a and 2021b of the sides 202a and 202b, the vortex 210 separates from the flow into the upper and lower regions of the trailing edge 201. A vortex 210a is formed which is rotating counterclockwise in the upper region of the trailing edge 201, that is, just below the side end point 2021a. There is another vortex 210b that is apparently under the direction of flow, rotating in the opposite sense, i.e. clockwise, which is formed on and / or beneath the lower side 202b. Downstream there is another vortex 210c that is rotating counterclockwise and slowly diffusing, which is also generated from the upper side 202a. The vortices 210a, 210b, 210c form a vortex system of so-called Cahmanwari streets. In the region of the vortices, i.e. between vortices, the pressure is considerably lower than the flow around the vortex vortex street.

As a result of the formation of Kamandu Street, the efficiency of the hydrofoil is reduced on the one hand, that is, on the rudder the rudder force is lowered. In addition, the hydrofoil, i.e., the drag of the direction bar, is also increased. On the other hand, the lateral force of the rudder is reduced, and vibrations may occur on the hydrofoil. The latter is a special case when the separation frequency of the vortex basically corresponds to the natural frequency of the hydrofoil body.

It is an object of the present invention to provide a hydrofoil wherein the vortex formation from the back to the flow direction of the hydrofoil, i.e. the adverse effects of the caman vortex street, is reduced.

This object is achieved by a hydrofoil having the features of claim 1.

A point of the present invention is to provide a protruding body on a posterior surface so that vortex formation is reduced. At present, the protruding body in the vortex is a body having a shape protruding from the trailing edge of the hydrofoil. Since the trailing edge generally crosses the longitudinal direction of the hydrofoil when viewed in cross-section, the projecting body generally protrudes at least in the downstream direction. This means that at least one protrusion protrudes from the trailing edge in the longitudinal direction of the hydrofoil and / or in the longitudinal direction of the hydrofoil-attached ship.

Said trailing edge being a surface terminating hydrofoil; Linear, concave, convex, or any other design. Therefore, the area of the trailing edge is generally designed as a plane or a ball. In particular, the trailing edge is not sloping and is not sharply designed. Also, the trailing edge is generally designed continuously from top to bottom and / or from side to side, thus constituting a single continuous area. The protrusions protrude from the surface, leading to the possibility that the separation of vortices is reduced. Thereby, the likelihood of occurrence of the Kahanwurst streets can be reduced. The effect of at least one protrusion depends not only on the exact placement, but also on various factors, such as the number of protrusions, the geometry, etc.

In the case of at least one protrusion, the inventors have dealt with the body, which is not inherently part of the trailing surface but is disposed in the latter and projects from the latter. Thus, in this sense, the protrusions are independent bodies that are preferred not to be finely convex from the trailing edge surface, for example, convex trailing edge or the like but to be firmly connected to the trailing edge, i.e., trailing edge surface. For this reason, at least one protrusion is not formed from the hydrofoil (hydrofoil material), and does not constitute a concave portion or the like. The protrusions can therefore be made, for example, of metal, in particular of steel, and can be connected to the trailing edge by welding or other suitable means and / or attachments. By virtue of the extrusion of the body from the trailing surface, it is possible to avoid the formation of a vortex pair rotating in opposite directions on both sides of the hydrofoil, which is indispensable for the formation of the Kaman vortex street. The at least one protrusion is preferably designed as a rigid non-flexible and inelastic body. According to this method, the flow behavior of hydrofoils, especially with respect to vortex formation, remains constant.

By providing at least one overhang, the likelihood of occurrence of caman vortex streams on the hydrofoil is reduced, which means that not only fuel efficiency but also hydrofoil drag is improved. In addition, the risk of damage to the hydrofoil and / or the watercraft of the watercraft is reduced by vibration. Because at least one protrusion is disposed posteriorly, this reduces the effective flow surface area of the hydrofoil; In addition, it is located outside the flow surface area and can not trigger cavitation due to flow separation, because it does not fall within the main flow field. Thus, by providing the flow body, a small amount of structural effort can be achieved, and also a good effect of reducing the formation of vortex in the area of the trailing edge, without weakening the cross section of the actual hydrofoil in terms of hydrodynamics. By means of at least one protrusion according to the invention, the process of vortex formation is reduced or prevented, so that a very stable and / or laminar flow pattern is produced when viewed from the rear of the hydrofoil in the direction of flow. The at least one protrusion is provided exclusively in the trailing edge rather than in another area of the hydrofoil.

With reference to the width of the trailing edge, at least one protrusion is preferably designed so as not to cover the entire width. This is preferably projected from the sub-area with reference to the trailing edge width. This ensures that blocking of the vortex flow is achieved. If at least one protrusion covers the entire width of the trailing edge, from a hydrodynamic point of view the protrusion can be operated as a pure extension of the trailing edge, and vortices rotating in the undesired opposite direction are separated from both sides of the protrusion .

To achieve as broad a reduction in vortex formation as possible, in a preferred embodiment of the present invention at least one protrusion is formed over at least 50%, preferably 75% of the trailing edge length, in the preferred embodiment over the entire length of the trailing edge . The term "trailing edge length" is to be understood as the deviation between the upper and lower ends of the hydrofoil in the region of the trailing edge in the present invention. The trailing edge is typically formed above the full height of the hydrofoil. Therefore, at least one protrusion is formed to be larger than the area of the trailing edge as far as possible, so that vortex formation is reduced (or damaged) as widely as possible by referring to the height of the hydrofoil. It is even more desirable if at least one protrusion is formed from one end of the trailing edge to the other end because damage to the vortex formation is guaranteed above the full height of the hydrofoil. Here, the at least one protrusion may preferably be constituted by a single body whose length corresponds to the length of the trailing edge and is attached to the trailing edge. However, in principle, at least one protrusion may be composed of a plurality of sub-bodies.

In principle, the at least one protrusion may be designed in any form when viewed in cross-sectional form. However, it is preferable that the cross section of the hydrofoil is formed such that at least one protrusion is basically parallel to the center line of the hydrofoil or along the center line. In this regard, at least one protrusion has a linear section. In a corresponding test, by means of the alignment of at least one protrusion of this kind, particularly good damage of the vortex formation, i. E. A particularly good flow pattern, can be produced. Particularly when the at least one cotter is disposed along the centerline, particularly regular damage of vortex formation on both sides of the hydrofoil is achieved. If a plurality of cooperators are provided, it is desirable that all of the projections are designed to be formed parallel to the centerline. However, each of the projections may be separated from this arrangement. In particular, this may be desirable in the case of a curved trailing edge, i. E. Having a concave or convex design. In this embodiment, the flow line of at least one protrusion when viewed in cross-section is associated with the shape of at least one protrusion between the trailing edge and its free end.

It is further preferred if at least one protrusion is formed essentially parallel to the longitudinal axis of the hydrofoil. Here, the longitudinal axis is an axis formed from the upper end of the hydrofoil to the lower end of the hydrofoil. For a rudder, the longitudinal axis will be the rudder rotation axis. The at least one protrusion may basically be formed parallel to the outer edge of the trailing edge. Here, the outer edge of the trailing edge is disposed parallel to the longitudinal axis of the hydrofoil. In this way, regular flow patterns continue to occur. In particular, this is preferred if at least one protrusion is formed parallel to the longitudinal axis and is formed over the entire length of the hydrofoil. Thereby, particularly regular flow patterns continue to be generated.

In another preferred embodiment of the present invention, at least one protrusion is protruded at a right angle, i.e., orthogonally, from the surface of the trailing edge. Here, the right angle is formed between the trailing edge and the axis (transverse axis) along the width of the hydrofoil. If the trailing edge surface is flat, in the case of a plurality of projections, the projecting bodies are arranged parallel to each other correspondingly. Thereby, the regularity of the flow from the back of the hydrofoil to the flow direction is further improved. In the case of an arcuate non-linear trailing edge, at least one protrusion may be disposed orthogonal to the section of the trailing edge adjacent to the at least one protrusion.

The width of the protrusion, that is, the distance between the trailing edge and the free end thereof, preferably corresponds to at least half of the trailing edge width. Experiments have shown that if at least one protrusion has a dimension in this manner, good results can be obtained for the reduction of vortex formation.

If at least two protrusions are provided, it is preferable to dispose the two protrusions apart from each other and / or arranged in parallel with each other. As a result of arranging the at least two protrusions apart, the vortex formation is more disturbed, because the two protrusions, which protrude independently of each other, block the vortex flow, Improves regularity.

In another embodiment, the following formula applies.

Number of protrusions = 2n + 1

Here, n is a natural number including 0. Particularly preferred is when n is 2, that is, when there are 5 protrusions. Also, when viewed in cross section, one protruding body is basically disposed at the center in the trailing edge, and when the number of protruding bodies is an even number, each protruding body is disposed on each side of the protruding body disposed at the center. A symmetrical arrangement is particularly preferred, and the midline of the hydrofoil when viewed in cross-section forms a line of symmetry. Each of the protrusions may be disposed apart from each other and / or arranged parallel to each other. Experiments have shown that this kind of design achieves particularly good effects on the reduction of vortex formation if the five projections are arranged symmetrically, especially when the projections are even. In this type of embodiment, the centrally disposed protrusions preferably have the widest width, i. E. The largest distance between the trailing edge and the free end. Alternatively, two protrusions of the same size may be disposed in the central region. Further, since the width of the other protruding body can be gradually reduced toward the outside, the outermost protruding body has the narrowest width. It is also preferred that the symmetrical design, that is, the pair of protruding elements arranged in the form of a mirror, has the same width in each case. Thereby, progressive blocking of the vortex flow from the inside to the inside is achieved.

If a plurality of protrusions are provided, the distances between the respective protrusions can be designed in principle to be the same or different. The most suitable arrangement from a hydrodynamic point of view depends on the environment in each case, in particular the shape and width of the trailing edge, the flow rate, and the precise design of the protrusion.

At least one protrusion is a rib protruding from the trailing edge and is particularly preferably designed in the form of a plate and / or a cross section of a square. The rib is made of, for example, a steel plate whose one end face is attached to the trailing edge. If the plate has an elongated design, especially if most or all of it is formed beyond the trailing edge length, the ribs or plates are well placed (i.e., adhered) to the trailing edge by one cross section in the longitudinal direction. With this kind of design, the arrangement of the strip-shaped ribs continues. If a plurality of projections are provided, it is preferable to arrange them parallel to each other or parallel to the longitudinal axis of the hydrofoil. Instead of having a plate shape, the ribs can be designed such that their free end regions are finely rounded, tapered toward their free ends, or are free. The ribs are preferably arranged in succession and / or the rectangular cross section of at least one protrusion is constant over the entire protrusion.

At least one protrusion is preferably provided for a hydrofoil designed with a fish tail ridge or a Schilling rudder, and when viewed in cross-section, the shape is widened away from the leading edge disposed in the opposite direction to the trailing edge in the direction of the trailing edge, ; It is formed so as to taper and taper from the central region to the rear region forming the narrowest point of the hydrofoil shape, and in particular to the rear region in the form of dovetail, in which the trailing edge is a linear, To the trailing edge. Due to the phase width of the trailing edge compared to the other hydrofoil shapes, vortex formation occurs particularly frequently in the hydrofoil configuration, as described above. In this regard, provision of at least one protrusion is particularly preferred for this kind of shape.

It is preferable that at least one protrusion is integrally formed as a body. This means that at least one protrusion does not include a through hole, a concave portion, or the like. Further, it is preferable that at least one protrusion has a constant cross-section.

Other objects, features and advantages of the present invention will become more apparent from the following detailed description when read in conjunction with the accompanying drawings.

1 is a perspective view of a hydrofoil having a trailing edge and a protruding body;
FIG. 1A is a detailed view of the upper end region of the trailing edge of FIG. 1; FIG.
Figs. 2A-2E are plan views of an end region of a hydrofoil having variously designed trailing edges and variously arranged or designed protrusions / protrusions. Fig.
Fig. 3 is a plan view on the end region of the hydrofoil with a protrusion protruding from the trailing edge in which the flow pattern is shown. Fig.
Figure 4 shows an end region of a hydrofoil of the prior art in which a flow pattern is shown.

In the description of the various embodiments of the present invention, the same parts have the same reference numerals.

1 shows a perspective view of the hydrofoil 100. As shown in Fig. In this case, the hydrofoil 100 is formed by a rudder having a fish-tailed shape or a Schilling® shape. The rudder includes a leading edge 10 and a trailing edge 20. The side surface (11) is formed between the leading edge (10) and the trailing edge (20). The end plate 14 is provided at the upper end 12 and the lower end 13 of the hydrofoil 100. The end region 15 of the rudder extends from the rear region 16 forming the highest point of the rudder towards the trailing edge 20 since the hydrofoil 100 takes the form of a fish tail shape. The trailing edge 20 is provided with all five protrusions 30 designed in the form of ribs in the form of plates and is formed in each case from the upper end 12 to the lower end 13 and arranged parallel to each other.

As can be seen from Fig. 1A, the central rib 30a has the widest width. Two ribs 30b and 30c are disposed on both sides of the center rib 30a, and the widths of the ribs are reduced toward the outside. The plate-shaped ribs 30a, 30b, 30c are attached to the trailing edge 20 with a linear design, i.e., a flat surface, by their longitudinal end faces. Further, the transverse end faces of the ribs 30a, 30b, 30c are in contact with the end plate 14 and are attached to the trailing edge as described above. The outer rib 30c has the narrowest width and is displaced slightly inward with respect to the outer side edge 21 of the trailing edge 20. Plate-shaped ribs 30a, 30b and 30c are each projected at right angles from the trailing edge surface and are formed parallel to the outer edge 21 of the trailing edge 20, that is, the longitudinal axis of the hydrofoil 100.

Figure 2a shows a top view of the hydrofoil end region 15 of Figure 1. The central rib 30a has the widest width b1 and the outer rib 30c has the narrowest width b3 and the rib 30b disposed between the ribs 30a and 30c has the intermediate width b2 . The distance a2 between the ribs 30c and 30b and the distance a1 between the ribs 30b and 30a are different and the distance a1 is longer than a2. The exact dimensions of the width and distance can in each case be associated with the optimum eddy reduction effect with respect to the trailing edge and the specific shape of the ribs. The ribs 30a are formed along the center line 17 and the ribs 30b and 30c are formed parallel to the center line 17. [ The center line 17 also forms a symmetrical axis for rib arrangement.

2B-2E illustrate another embodiment of the shape of the end region 15 of the hydrofoil 100 according to the present invention. Thus, in FIG. 2B, the central ribs 30a are provided arranged along the centerline 17. Two ribs 30c are provided, each of which is arranged at an outer position and designed to have the same width. The ribs 30c are arranged symmetrically with respect to the center line 17. In the design with three ribs of Figure 2b, the trailing edge 20 has a concave design when viewed in plan or cross-section. In FIG. 2C, the trailing edge, on the contrary, has a linear design, that is, the trailing edge forms a flat surface. Only one rib 30a is disposed along the centerline 17. In FIG. 2d, the trailing edge 20 has a concave design in a manner similar to FIG. 2b when viewed in plan or cross-sectional view. Likewise, one central rib 30 is formed along the centerline 17, and the two outer ribs are also identical. 2b, all three ribs are arranged in parallel, and two outer ribs 30c, as in Fig. 2a, are not designed to be parallel to the centerline 17, i.e., the central rib 30a, Respectively. In particular, they are formed in a direction away from the outer edge toward the inner edge. In Figure 2e, five ribs are provided and the trailing edge 20 has a convex design when viewed in plan or section. Again, the central ribs 30a having the widest width are disposed along the centerline 17. The two outer ribs 30c have the narrowest width. In each case, the ribs 30b and 30c disposed on the right and left sides of the center line 17 are symmetrically arranged with respect to the center line 17. [ 2a, the ribs 30b, 30c are disposed parallel to the centerline 17, i. E. Parallel to the ribs 30a, but in each case about 90 degrees from the convex shape of the trailing edge 20 So that when the ribs 30a, 30b, and 30c are observed from the trailing edge toward the free ends thereof, the ribs are outwardly directed to form a fan. All the ribs 30a, 30b, and 30c shown in Figs. 2A to 2E are designed as plates.

3 is a plan view showing an end region 15 of the hydrofoil 100 according to the present invention. The trailing edge 20 has a linear design when viewed in plan or cross-section. The two ribs 30a, 30b and 30c protruding from the trailing edge 20 are basically arranged and designed in accordance with the arrangement of FIG. 2a and are arranged and arranged between the ribs 30c and 30b as shown in FIG. The distance is longer than the distance between the ribs 30b and 30a. The flow pattern is shown with a plurality of arrows. Thus, by the hydrofoil design according to the present invention, a flow pattern which is basically linear is set in the region of the side wall 11 downstream from the hydrofoil 100. [ A vortex 40 is formed between the upper rib 30b and the central rib 30a, which rotates counterclockwise. Also, due to the interruption action caused by the ribs 30a, 30b, 30c, it is possible to recognize how vortex formation can not occur in the intermediate space between the respective ribs. The laminar flow pattern in the flow direction is already set at a short distance behind the vortex 40 over the entire width of the hydrofoil 100. [ In addition, only a single vortex 40 is generated, thereby inhibiting the formation of Caman-vortex streets in each case formed by pairs of vortices rotating in opposite directions.

10: leading edge 11: side
12: upper end portion 13: lower end portion
14: end plate 15: end region
16: rear region 17: center line
20: trailing edge 21: outer edge
30: protrusion 40: vortex
100: hydrofoil 200: hydrofoil (prior art)
201: trailing edge 202a, 202b: side surface
2021a, 2021b: side end point 210: vortex

Claims (14)

In a marine hydrofoil (100) having a trailing edge (20)
At least three protrusions 30 are disposed in the trailing edge 20 to reduce vortex formation,
Each of the at least three protrusions 30 is designed in the form of a plate protruding from the trailing edge 20 or as a rib,
The at least three protrusions (30) are not formed from the hydrofoil and do not form a recess or a recess or groove in the hydrofoil,
The at least three protrusions (30) are spaced apart from each other,
Characterized in that the width of the at least three protrusions gradually decreases toward the outward direction of the hydrofoil so that the protrusion located farthest from the center line of the hydrofoil has the shortest width. The hydrofoil of claim 1 wherein at least one of the at least three protrusions (30) is at least 50% of the length of the trailing edge (20). 3. A hydrofoil (100) as claimed in claim 1 or 2, wherein, in the cross-section of the hydrofoil (100), at least one of the at least three protrusions (30) And extending along the longitudinal axis. The hydrofoil of claim 1 or 2, wherein at least one of the at least three protrusions (30) extends parallel to a longitudinal axis of the hydrofoil (100). 3. The hydrofoil according to claim 1 or 2, wherein at least one of the at least three protrusions (30) projects perpendicularly from the surface of the trailing edge (20). 3. The hydrofoil of claim 1 or 2, wherein at least one width of the at least three protrusions (30) corresponds to at least half of the width of the trailing edge (20). 3. The hydrofoil according to claim 1 or 2, wherein at least two of the protrusions (30) extend parallel to each other. 3. The method according to claim 1 or 2, wherein the number of the protrusions (30) is 2n + 1; One projecting body 30a is disposed at the center on the trailing edge 20 and the even projecting bodies 30b and 30c are disposed on both sides of the projecting body 30a disposed at the center hydrofoil. 9. The hydrofoil according to claim 8, wherein the protruding body (30a) disposed at the center has the widest width. A hydrofoil according to any one of the preceding claims, characterized in that at least three protrusions (30) are provided, the distances between the respective protrusions (30) being the same or different. The hydrofoil (100) of claim 1 or 2, wherein the hydrofoil (100) is widened from the leading edge (10) disposed on the opposite side of the trailing edge (20) , Which forms the widest point of the hydrofoil shape and which tapers from the central region to the rear region 16 forming the narrowest point of the hydrofoil shape from the rear region 16 to the trailing edge 20 Which is once again spread in the form of dovetail. 12. The hydrofoil of claim 11, wherein the trailing edge (20) has a linear, convex, or concave design. A waterborne vessel having the hydrofoil (100) according to any one of the preceding claims. delete

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