WO2005090155A1

WO2005090155A1 - Transport means comprising improved streamlined characteristics

Info

Publication number: WO2005090155A1
Application number: PCT/EP2005/002793
Authority: WO
Inventors: Iraklievich Gennady Kiknadze; Ivan Alexandrovich Gachechiladze
Original assignee: Vida, Nikolaus
Priority date: 2004-03-16
Filing date: 2005-03-16
Publication date: 2005-09-29
Also published as: EP1725449A1; DE102004013035A1

Abstract

The aim of the invention is to improve the streamlined characteristics of transport means (10), which move in relation to a surrounding medium and to reduce specific detrimental flow effects, such as the formation of trailing vortices and lee-side circulation. To achieve this, the invention provides transport means comprising at least one structured surface (101), containing a plurality of depressions and/or protuberances and relates to the use of a surface that contains a plurality of depressions and/or protuberances as the surface of transport means. The invention also relates to a layer that can be applied to a surface or part of a surface of transport means, said layer having a structured exterior comprising a plurality of depressions and/or protuberances.

Description

Means of transportation with improved flow properties

description

The invention relates generally to means of transportation and in particular to means of transportation along whose surface a medium flows, the medium being able to comprise a gas, a liquid or a mixture of gas and liquid.

It is known that the flow properties of a

Means of transport that move in a medium depend on a number of parameters. This includes, among other things, the properties of the medium, the shape of the means of transportation, and the relative speed of the means of transportation and the medium.

In order to reduce the flow resistance and to avoid other negative flow properties as much as possible, vehicle manufacturers are continually optimizing the geometry of vehicles with great expenditure of time and money. This affects land, water and air vehicles to varying degrees. However, there are limits to the suppression of certain negative flow effects by adapting the vehicle geometry.

The pressure compensation at the rear end of a moving object creates so-called drag vortices, for example. Even in the transition phase between laminar and turbulent flows, it can happen that large drag vortices are formed when the laminar flow is torn off. The generation of such uncontrolled large Trailing vortices require energy and therefore lead to a considerable braking effect.

This is particularly a problem in aviation, since such large eddies remain stable for a longer period of time and can thereby affect subsequent aircraft. Trailing vortices can also be observed in land and water vehicles.

Another problem is the formation of leeward rollers

Crosswinds. These are large eddies that form on the side of an object facing away from the wind. Due to the resulting pressure difference, this leads to an increased risk of the train tipping over, especially in high-speed trains.

Furthermore, the formation of turbulent eddies is usually associated with a high level of noise and vibration.

The invention has for its object to show a new way how the flow properties of a means of transportation that moves relative to a surrounding medium can be improved and the disadvantageous effects described above can be reduced.

The object is achieved in a surprisingly simple manner by an object according to one of the attached independent claims. Advantageous embodiments and further developments are described in the subclaims. The inventors have surprisingly found that in the case of means of transportation whose surface at least partially has a special three-dimensional surface structure, as described in EP 92 911 873.5, PCT RU92 / 00106 and in EP 96 927 047.9, PCT / EP96 / 03200, not only is the flow resistance reduced, but also other negative flow effects are reduced. The disclosure content of EP 92 911 873.5, PCT RU92 / 00106 and EP 96 927 047.9, PCT / EP96 / 03200 is therefore hereby expressly incorporated by reference.

Accordingly, a means of locomotion according to the invention comprises at least one surface which is structured with a plurality of depressions and / or elevations, a surrounding medium flowing along this surface when the means of locomotion moves.

The at least one surface is advantageously designed such that vortices form in the surrounding medium in the vicinity of the surface when the medium flows along the surface.

The formation of vortices near the surface in the surrounding medium by an inventive

Deepening can be described as follows. A vortex roll is initially formed on the depression essentially transversely to the direction of flow. Because this vortex roll typically has non-zero helicity, the medium is drawn into the vortex at one end and ejected at the other end. As a result, the latter end of the vortex detaches from the surface and is carried away by the main flow. In this way, vortices are formed which, starting from the depressions, lead away from the surface in the direction of the main flow. Since the pressure inside the vortices is lower than in their surroundings, the boundary layer of the medium near the surface is drawn off and directed into the main flow. Each vortex acts as a kind of boundary layer controller, which in the surrounding medium in all directions of the environment, also against the governing flow direction. As a result, disorderly turbulence present in the medium is reduced in the vicinity of the surface.

Due to the formation of vortices described, the stall is shifted backwards along the flow direction compared to a smooth surface, and the negative flow effects described above, such as the formation of drag vortices or leeward rolls, are reduced. The

Reducing the formation of drag vortices also leads to a reduction in the total resistance.

The depressions and / or elevations advantageously have a two-dimensionally delimited edge and are particularly advantageously rounded off in the region of the edge toward the rest of the surface with a predetermined radius of curvature. The radius of curvature can have a different value in different directions within the plane of the surface.

The depressions preferably essentially have the shape of a section of a sphere or an ellipsoid, since this shape is the easiest to implement in terms of production technology.

The shape, size and arrangement of the depressions and / or elevations can advantageously be matched to different flow conditions which are predetermined by the intended use of the means of transportation. In order to achieve a flexible adaptation of the surface structure of the means of transportation to different states of motion during use, the means of transportation advantageously comprises a device for varying the shape and / or the number of depressions and / or surveys. For example, this can be done using flexible membranes, as described in EP 96 927 047.9. EP 96 927 047.9 is therefore hereby expressly incorporated by reference.

In a preferred embodiment, the depressions and / or elevations are arranged at least in sections essentially periodically on the surface of the means of transportation.

In order to achieve the most complete possible surface coverage with the structuring, the surface of the means of transportation, which has the depressions and / or elevations, expediently comprises at least a first, essentially flat region and at least a second, essentially curved region. In this way, the structured surface can be adapted to any geometry of the means of transportation.

Since different flow conditions typically prevail in the flat and the curved region of the surface of the means of transportation, the depressions and / or elevations in these regions advantageously differ in shape and / or size and / or arrangement.

In a particularly preferred arrangement of the depressions and / or elevations in a substantially flat area of the surface of the means of transportation, the centers of three directly adjacent depressions and / or elevations form an equilateral triangle, the distance between the centers of two adjacent depressions and / or elevations being one substantially constant first value and the distance between two successive rows of depressions and / or elevations essentially one have a constant second value. In a curved area, the surface preferably has a similar arrangement that takes the surface curvature into account.

A preferred embodiment of a means of transportation according to the invention comprises a land vehicle, in particular a rail vehicle or a truck or passenger car, with at least one outer shell, at least parts of the surface of the outer shell having a plurality of depressions and / or elevations.

The surface of the means of transportation particularly preferably has a multiplicity of depressions and / or elevations in such a way that the formation of leeward rollers is reduced compared to an otherwise identical one

Means of transportation whose surface has a smooth structure. This is particularly advantageous if the means of transportation is designed as a rail vehicle, in particular as a high-speed train.

A further preferred embodiment of a means of transportation according to the invention comprises an aircraft, in particular an aircraft or helicopter, with at least one of the components outer shell, propeller, rotor, turbine, aerofoil, steering surface or tail unit, at least parts of the surface of one of these components having a plurality of depressions and / or have surveys.

A preferred embodiment of a means of transportation according to the invention is also a watercraft, comprising at least one hull and / or a drive screw, at least parts of the surfaces of the hull and / or the drive screw having a plurality of depressions and / or elevations. In addition, any other types of means of transportation, such as surfboards, bobsleighs or rockets, with a surface which has a multiplicity of depressions and / or elevations are also within the scope of the invention.

Particularly preferred is the surface of the means of transportation, which has a multiplicity of depressions and / or elevations, over an otherwise identical means of transportation, the surface of which has a smooth structure,

- The drag vortex formation is reduced and / or

- The formation of leeward rollers is reduced and / or - the flow resistance is reduced and / or

- The position of the stall relative to the direction of movement of the means of transportation moved back and / or

- The noise development is reduced and / or - The vibration development is reduced and / or

- The deposition of particles on the surface is reduced and / or

- reduces the formation of ice on the surface.

Accordingly, the invention also includes the use of a surface, which has a plurality of depressions and / or elevations, as the surface or part of a surface of a means of transportation for one or more of these purposes.

Furthermore, the invention comprises a layer, in particular in the form of a film, for application to a surface or parts of a surface of a means of transportation, the outside of the layer having a structure which has a plurality of depressions and / or Surveys. By applying such a layer, the advantages according to the invention can also be achieved by retrofitting conventional means of transportation.

The invention is explained in more detail below on the basis of preferred exemplary embodiments and with reference to the accompanying drawings, in which the same reference numerals refer to the same or similar components in the individual drawings.

Show it

FIG. 1: a schematic representation of a first embodiment of a means of transportation according to the invention, FIG. 2: a schematic illustration of a second embodiment of a means of transportation according to the invention, FIG. 3: a schematic illustration of a third embodiment of a means of transportation according to the invention,

FIG. 4: a schematic illustration of a drive screw of a means of transportation according to the invention, FIG. 5: a schematic illustration of a rotor of a means of transportation according to the invention,

Figure 6: schematically the cross sections of two wings, Figure 7: schematically a central cross section of a first embodiment of a depression or elevation perpendicular to the surface, Figure 8: a schematic representation of a first distribution of depressions or elevations, Figure 9: schematically a central cross section a second embodiment of a depression or elevation perpendicular to the surface, FIG. 10: a schematic representation of a second distribution of depressions or elevations,

FIG. 11: schematically a central cross section perpendicular to the surface of a third embodiment of depressions or elevations with the corresponding top view,

Figure 12 is a schematic representation of an embodiment of a surface with depressions or elevations, which has flat and curved areas.

1 shows a high-speed train 10, the outer surface 101 of which has a large number of depressions. When the train moves, the mechanism described above generates secondary vortices in the air flowing along the surface from these depressions. These self-organizing vortex structures suck off the boundary layer near the surface and direct it into the main flow, reducing the flow resistance and reducing various negative flow effects. Of particular importance here is the reduced formation of leeward rollers in cross winds, which is a major problem with conventional high-speed trains.

A conventional jet jet 20 is shown in FIG. 2. In this exemplary embodiment, the surfaces 201 of the wings 22 have a structuring with a multiplicity of depressions and / or elevations. This structuring can be provided during the production of the wings or can also be generated by a subsequently applied layer, for example by applying a film which has the structuring. The structured surface can of course also advantageously be used Further surfaces of such an aircraft are provided, such as the fuselage 21, the rear tail units 23 and 24 or the outside of the drive units 25. The turbine blades of the drive units 25 could also have a surface structured according to the invention. Advantageous effects of an aircraft according to the invention are, for example, a reduction in the formation of drag vortices and an improvement in the stall properties. The invention also reduces in particular

Problem of supersonic aircraft of heating the outer shell by a significant reduction in surface resistance. At the same time, the heat transfer between surface and medium is improved by the surface structuring according to the invention, which also contributes to a reduction of this problem.

FIG. 3 shows a ship 30 in which the surface 301 of the hull 31 lying below the water line 40 has a structure with a large number of depressions. A surface 331 structured according to the invention can also be provided on the leaves 34 of the drive screw 33. This is shown again in detail in FIG. 4.

FIG. 5 shows a rotor 50 of a helicopter according to the invention with two rotor blades 51, the surface 501 of which has a large number of depressions and / or elevations. In this embodiment, too

Flow properties can be positively influenced in this way. In the case of helicopters, this affects in particular through improved lift, improved stall properties and a reduction in noise. On the stall properties of a propeller can be improved in the same way.

Figure 6 shows the cross-section of a profile of a conventional wing 26. The elongated profile is necessary to avoid an early stall which would result in loss of lift. However, if the surface of an aerofoil has a large number of depressions and / or elevations, the point of the stall shifts along the

Direction of flow to the rear, which enables completely new wing profiles. Such a profile 27 is shown in FIG. 6 by way of example, placed over the conventional profile 26 for comparison. Such new wing profiles can significantly increase the lift or, with the same lift, the dimensions of the wing can be significantly reduced.

FIG. 7 shows a central cross section of a preferred shape of a depression 602 perpendicular to a flat surface. The depression 602 in this exemplary embodiment has the shape of a section of a ball or a spherical cap with radius Ri, height h and diameter d, and is rounded off with a rounding radius R ₂ . In this example, a depression is rotationally symmetrical to an axis of rotation through the center of the depression perpendicular to the surface.

8 shows a preferred distribution of the depressions 602 on a flat surface. The depressions 602 are arranged periodically, the centers of three directly adjacent depressions 602 forming an equilateral triangle. The angle α is therefore 60 °. The distance between the centers of two neighboring ones Indentations 602 and thus the side length of the triangle mentioned is t ₂ . The distance between two successive rows of depressions 602 and thus the height of the triangle mentioned is t _x . ti and t ₂ can have different values depending on the application.

FIG. 9 shows a central cross section of a further preferred form of a depression 702 perpendicular to a flat surface. The depression 702 in this exemplary embodiment has the shape of a section of an ellipsoid with the diameters Ei, E ₂ and E ₃ , where E _{3 is} perpendicular to the plane of the drawing and is therefore not shown. The depression has a height h and a diameter d and is rounded off with a radius of curvature R ₃ .

10 shows a preferred distribution of the depressions 702 on a flat surface. This corresponds essentially to the arrangement shown in FIG. 8 for the depressions 602.

Further advantageous shapes and arrangements of the depressions and / or elevations can be found in the applications EP 92 911 873.5, PCT RU92 / 00106 and EP 96 927 047.9, PCT / EP96 / 03200. Accordingly, the

Surface advantageously has a three-dimensional structure, as is shown schematically by way of example in FIG. 11, with depressions or elevations 802, curved areas and transition areas. In the cross section of the surface shown in the upper area of FIG. 11, the depressions or elevations extend along their diameter d, the curved areas along the distance l _c and the transition areas along the distance l _t r. The distance between two depressions is again included denotes t ₂ . Any portion of the indentations or bumps 802 along the surface is in the form of a smooth and continuous line that can be described by the following relationship: φ 1. 4πφ * (φ _t z): * Y {h, θ) - - + Ar -sin- + h 180 ° 4π 180 °. πφ 1. 3πφ. 2πφ 1. Aπφ + -4 _j Δr sin— ^L sin—— + A ₂ Ar \ sin— sin—— (1) 180 ° 3 180 ° J 180 ° 2 180 °

wherein:

- r (φ, z) is the section radius in the direction of the angle φ (in angular dimension), from the distance connecting the centers of adjacent depressions and / or elevations or from any distance lying in the marked section to count;

- z is the section height above the lowest point of the depressions or the section distance from the highest point of the elevations;

- r (?, θ) is the radius of the recess or elevation section in the direction of the angle φ = 0 °;

- Δr = r (b, 180 °) - r (7th, 0 °) is the difference between the radii of the depression or elevation section in the direction of the angles <ρ = 180 ° and φ = 0 °;

- l _{c is} the dimension of the curved area projected onto a plane parallel to the plane of the surface;

- k is a coefficient with 0.3 <k <0.7;

- Ai is a coefficient with -1 <Ai <1;

- A _{2 is} a coefficient with -1 <A ₂ <1; and - h is the depth or height of the depressions or elevations. In the curved areas, the depressions or elevations are advantageously rounded off with a radius of curvature of R> 3 - h towards the transition areas.

The value of h is advantageously between 0.005 and 0.3 times the thickness of the boundary layer. With d the diameter of the depressions or elevations, the following relationships also preferably apply:

2 - h <d <40 - h, in particular 2 - h <d <\ 0 - h, 0.3 • d <l _c <0.5 • d and 0.05 - d <l _tr <3 - d.

The parameters contained in equation (1) can be selected differently depending on the type of medium, the shape and dimensions of the surface, the flow rate, the temperature of the medium and the surface, and other factors influencing the flow.

FIG. 12 shows a surface that has at least one flat region 601 and one curved region 901. If a medium flows around such a surface, it is advantageous, due to different flow conditions in the different areas, if the

Distinguish depressions or elevations 602 in the flat region 601 in shape and / or size and / or arrangement from the depressions or elevations 902 in the curved region 901. This may also be necessary solely for geometric reasons, since if the surface is strongly curved, for example, a meaningful size of the depressions or elevations is limited. FIGS. 13 a and 13 b show the model of a train with a surface which has a large number of depressions. The shape of the depressions used in this model essentially corresponds to that shown in FIG. 7, adapted to the curvature of the surface. A variation in the size and distribution of the depressions between differently curved areas of the surface can also be seen.

The flow properties of this model were analyzed in one

Wind tunnel measured. This resulted in a 16% reduction in surface resistance and a significantly reduced formation of leeward rollers. Furthermore, measurements in a medium with turbulent flows showed a significant reduction in the development of vibrations.

Claims

claims

1. means of transportation (10, 20, 30) with at least one surface (101, 201, 301) along which a medium flows when the means of transportation (10, 20, 30) moves, the at least one surface (101, 201, 301) has a structure which comprises a multiplicity of depressions and / or elevations (602, 702, 802, 902).

2. Means of transportation (10, 20, 30) according to claim 1, wherein the at least one surface (101, 201, 301) is designed such that in the vicinity of the at least one surface (101, 201, 301) vortices in the surrounding Form medium when the medium flows along the at least one surface (101, 201, 301).

3. Means of transportation (10, 20, 30) according to any one of the preceding claims, wherein the depressions and / or elevations (602, 702, 802, 902) in the region of the edge to the rest of the surface (101, 201, 301) are rounded off ,

4. Means of transportation (10, 20, 30) according to any one of the preceding claims, wherein the depressions and / or elevations (602, 702) substantially in the form of a

Have sections of a sphere or an ellipsoid.

5. Means of transportation (10, 20, 30) according to any one of the preceding claims, comprising means for varying the shape and / or the number of depressions and / or elevations (602, 702).

6. Means of transportation (10, 20, 30) according to any one of the preceding claims, wherein the depressions and / or elevations (602, 702, 802, 902) at least in sections are arranged periodically on the at least one surface (101, 201, 301).

7. Means of transportation (10, 20, 30) according to any one of the preceding claims, wherein the at least one surface (101, 201, 301) at least a first, substantially flat region (601) and at least a second, substantially curved region (901 ) includes.

8. Means of transportation (10, 20, 30) according to claim 7, wherein the depressions and / or elevations (602, 902) in the at least one first area (601) and in the at least one second area (901) in shape and / or distinguish size and / or arrangement.

9. Means of transportation (10, 20, 30) according to claim 7 or 8, wherein at least in the at least one first, substantially flat region (601) of the at least one surface (101, 201, 301) the centers of three directly adjacent depressions and / or elevations (602) form an equilateral triangle and the distance between the centers of two adjacent depressions and / or elevations (602) is a substantially constant first value (t ₂ ) and the distance between two successive rows of depressions and / or elevations (602) is one have a substantially constant second value (ti).

10. Means of transportation (10) according to one of the preceding claims, designed as a land vehicle, in particular as a rail vehicle or 'as a truck or passenger car, comprising at least one outer shell, at least parts of the surface (101) of the outer shell having a plurality of depressions and / or elevations exhibit.

11. Means of transportation (10) according to claim 10, wherein by the at least one surface (101) having a plurality of depressions and / or elevations, the formation of leeward rollers is reduced compared to an otherwise identical means of transportation, in which the at least one surface has a smooth structure having.

12. Means of transportation (20) according to any one of the preceding claims, designed as an aircraft, in particular as an aircraft or helicopter, comprising at least one

Outer shell and / or a propeller and / or a rotor and / or a turbine and / or an aerofoil and / or a steering surface and / or an empennage, wherein at least parts of the surfaces (201) of the outer shell and / or the propeller and / or of the rotor and / or the turbine and / or the airfoil and / or the steering surface and / or the tail unit have a plurality of depressions and / or elevations.

13. Means of transportation (30) according to one of the preceding claims, designed as a watercraft, comprising at least one hull (31) and / or a drive screw (33), at least parts of the surfaces (301) of the hull (31) and / or the drive screw (33) have a multiplicity of depressions and / or elevations.

14. Means of transportation (10, 20, 30) according to one of the 'preceding claims, wherein the at least one surface (101, 201, 301) which has a plurality of depressions and / or elevations (602, 702, 802, 902) , compared to an otherwise identical means of transportation, in which the at least one surface has a smooth structure, - the formation of drag vortices is reduced and / or - the formation of leeward rollers is reduced and / or - The flow resistance is reduced and / or

- The position of the stall is shifted backwards relative to the direction of movement of the means of transportation (10, 20, 30) and / or - the noise is reduced and / or

- The vibration development is reduced.

15. Means of transportation (10, 20, 30) according to any one of the preceding claims, wherein the deposition of particles on the at least one surface (101, 201, 301), which has a plurality of depressions and / or elevations, is reduced compared to a smooth Surface when a medium flows along the surface.

16. Means of transportation (10, 20, 30) according to one of the preceding claims, wherein the ice formation on the at least one surface (101, 201, 301), which has a multiplicity of depressions and / or elevations, is reduced compared to a smooth surface, when a medium flows along the surface and the surface is at a lower temperature than the medium.

17. Use of a surface which has a multiplicity of depressions and / or elevations as surface (101, 201, 301) of a means of transportation (10, 20, 30) for

- Reduce drag vortex formation and / or

- Reduce the formation of leeward rollers and / or

- Reduce the flow resistance and / or

- Moving the position of the stall backwards relative to the direction of movement of the

Means of transportation (10, 20, 30) and / or

- Reduce noise and / or

- Reduce vibration development and / or

- Reduction of particle deposits when a medium flows along the surface, and / or - Reduce ice formation when a medium flows along the surface.

18. Layer, in particular film, for application to a surface or parts of a surface of a means of transportation, the outside of the layer having a structure which comprises a plurality of depressions and / or elevations.