Device and method for conversion of continuous medium flow energy

Description

CROSS-REFERENCES TO RELATED APPLICATIONS

The present application is claiming priority of European Patent Application No. 03006432.3, filed on Mar. 21, 2003 and PCT International Application No. PCT/EP2004/003015, filed on Mar. 22, 2004, the content of which is herein incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to power engineering and, in particular, to the methods and devices for conversion of the continuous medium flow energy using vortex streams.

This invention may be used in wind and hydraulic driven power engineering in various hydraulic and gas dynamic systems, for instance, when the motion of liquids, gas, two-phase or multicomponent media is used for mechanical energy generation or conversion.

The invention can be most successfully used in wind-driven electric power plants, in hydroelectric power plants, arranged in river beds (without dams), in tide-driven hydroelectric power plants, as well as when the energy of thermoinduced flows is utilised including sun-heated thermoinduced flows.

2. Description of Related Art

Wind energy is commonly converted using horizontal-axis wind turbines. However, this concept requires the axis to be rotatable around a second vertical axis in order to set the rotating axis parallel to the wind stream, resulting in an expensive arrangement.

Yet, the concept of horizontal-axis wind turbines is generally preferred, as the vanes of a horizontal wind-turbine in upper position extend vertically beyond the supporting tower. This is advantageously, as the wind velocity, which is crucial for effective wind energy conversion increases with increasing height.

Low fluid stream velocities are a general problem encountered with wind power plants. In consequence thereof, wind power-plants require large vanes and, coming along therewith, large and heavy moving parts.

To overcome this disadvantages, several methods of concentration of the wind flow power have been considered.

A known method of wind flow power concentration contemplates to place devices in the form of a convergent-divergent reflector into the wind, which are arranged coaxially with the direction of flow of the wind to increase its velocity and hence the power of the flow directed onto the power generating units of the above indicated electric plants.

What is common for such methods is that the profitability of their utilisation in wind-driven power generating systems of different type depends on the average velocity V of the flow.

Further prior art methods for the conversion of the continuous medium flow energy into mechanical energy are known whereby a rotational moment is imparted to the flow, and this moment is directed into an inlet chamber and into a system of channels; a reduced pressure is created in the flow and this ensures an inflow of the medium from the external space and a concentration of the power in the formed flow; then the flow energy accumulated in this way is converted by means of the rotary-action mechanism (Ragwalla A. A., Hsu C. T. “Power Coefficient of Tornado-Type Wind Turbines”. Journal Energy, 1983, V. 7, No. 66, p. 735-737; Hsu Ñ. Ò., H. Ide. “Performance of Tornado-Type Wind Turbines with Radial Supply”. Journal Energy, V. 7, No. 6, 1983, p.452-453).

The devices which realise this method are called TWES (Tornado Wind Energy Systems) and they essentially are towers inside of which a tornado-like vortex flow is generated. As it was already mentioned, this flow originates due to the inflow of air inside the tower through one or a multiplicity of slots forming an arbitrary, but permanent for the given structure, angle with the local radius of the tower.

The slots in the tower are open on the windward side and closed on the leeward side. Upon passing through these slots the wind acquires a tangential velocity component, and this involves the origination of a vortex flow inside the tower. A reduced pressure zone is formed in the core of such flow, and this results in the suction of additional masses of air inside the tower through the tower bottom, installed on a special device designed for creating a draught.

One disadvantage of known TWES is that the means for vortex generation and the inlet are generally arranged at the lower part of the tower in order to generate a tornado-like flow which is rotating around a vertical axis and having an upwardly directed mean flow direction. Naturally, the flow velocity in this part of the tower is considerably lower compare to the upper end, resulting in a reduced effectiveness of power conversion.

BRIEF SUMMARY OF THE INVENTION

The problem to be solved by the invention therefore is to provide a method and device for conversion of the energy of medium flows having an increased efficiency for continuous medium flow conversion. This problem is solved in a surprisingly simple manner by a device and a method according to the present invention.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 schematically depicts a first exemplary embodiment of a fluid guiding structure according to the present invention; and

FIG. 2 schematically depicts a second exemplary embodiment of a fluid guiding structure according the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Accordingly, an inventive device for conversion of the energy of medium flows comprises a fluid guiding structure having a lower and an upper opening, a turbine arranged inside said fluid guiding structure and means for generating a vortex flow inside and along said fluid guiding structure, and a flow inlet chamber arranged on the upper opening of said fluid guiding structure.

The inventive method for conversion of the energy of medium flows, which may particularly carried out employing an inventive device, comprising the steps of

generating a vortex flow along a fluid guiding structure with a lower and an upper opening, whereby the vortex flow having a main flow direction directed from one of the openings to the other,

generating at least one vortex in an inlet chamber arranged on top of said fluid generating structure, and

converting flow energy from the vortex flow inside said fluid guiding structure.

Most preferably, the vortex generating means comprises at least one fixed component, such as a fixed guiding vane to impart turbulent or vortex flow to the continuous medium flow inside of the device. Thereby, large scale devices may be readily constructed without using expensive large and heavy movable components.

By arranging the inlet chamber on top of the fluid guiding structure, the fluid inlet is subjected to higher flow velocities compared to the flow velocities at the lower opening of the fluid guiding structure, thus increasing the efficiency of the inventive device and method.

The setup of the inlet chamber and the fluid guiding structure may be similar to the devices as disclosed in EP 92 911 873.5 being the European regional phase of PCT/RU92/00106 and in EP 96 927 047.9 being the European regional phase of PCT/EP96/03200, which are are apt to generate contributing vortices without a generation of essentially any harmful or negative vortices. Both documents EP 92 911 873.5 being the European regional phase of PCT/RU92/00106 and EP 96 927 047.9 being the European regional phase of PCT/EP96/03200 are incorporated herein by reference.

The means for generating a vortex flow may advatageously comprise at least one vortex generating surface arranged inside said inlet chamber.

The main flow direction inside the fluid guiding structure may be from the upper towards the lower end or vice versa, depending on the geometry and shape of the fluid guiding structure and the means for generating the vortex flow.

According to one embodiment of the invention, the means for generating a vortex flow further comprises a system of channels wherein a surface or part of a surface of said chambers and systems of channels generates vortices.

Specifically, the continuous medium flow to be converted may be influenced by a field of forces at least in its wall region of the surface or part of a surface within a range of distances yn along the normal from the surface or part of a surface. A turn of the velocity vectors of the continuous medium particles is caused repeatedly in space and/or in time by said influence of said forces, whereby the influence is causing the turn in a range of angles α alternately towards the surface or part of a surface and from it away and in a range of angles β alternately to the left and to the right with regard to the direction of the velocity vectors of the continuous medium particles of the near-wall flow. Further, the range yn may advantageously amount to 0.005 to 0.3 times the boundary layer thickness δ, or the equivalent hydraulic diameter of the pressure channel, or the characteristic hydraulic dimension of the near-wall flow. Favorably, the angle α is between α=0.02 to 0.5 radian and the angle β is between β=0.02 to 0.3 radian.

The intensity of the influence or the strength of the forces may further be such that the minimum curvature radius R_min, of the trajectory of the flow of said particles is from 2 to 30 average distances S along the normal from the streamlined wall to the curved trajectory of the particle, whereas one or both of the belowstanding features a) and/or b) is/are valid

• • a) the spatial repetition of said influence being λ∥=(3 to 30) yn along the direction of the wall flow and λ⊥=(1 to 10) yn perpendicular to the direction of the wall flow,
  • b) the time repetition T being from 3 to 30 times the distances yn divided by the average velocity v in the boundary or wall layers. Harmful secondary vortices may be favorably minimized as disclosed in RU 20 59 881. Further, according to yet a further embodiment the flow to be converted is directed into the internal axissymmetric volume along two systems of trajectories converging towards the axis of symmetry of the volume; the first system forms a vortex flow just in front of the zone of conversion of the rotational moment and mechanical energy, it concentrates the mechanical energy and rotational moment in the axissymmetric volume and ensures further conversion of the mechanical energy and rotational moment in the same volume, whereas the second system of trajectories forms a flow with a reduced pressure thus ensuring evacuation of the continuous medium flowing out of the mechanical energy and rotational moment conversion zone. The first system of trajectories will at first fill that space area, which is limited by two surfaces of revolution of the fluid guiding structure and/or the inlet chamber, and then it will assume the form of helices; in the second system of trajectories the flow is swirled up along the main flow direction inside the fluid guiding structure, depending, whereas the first system trajectories adjoining the surfaces of revolution are first rendered a shape in accordance with the dependencies given below: Z 1 ⁡ ( r ) = C 1 ⁡ [ r - R 0 NR 0 - R 0 - 1 2 ⁢ π ⁢ sin ⁢ 2 ⁢ π ⁡ ( r - R 0 ) NR 0 - R 0 ] , Z 2 ⁡ ( r ) = C 2 / r 2 + C 3 ⁡ [ r - R NR 0 - R - 1 2 ⁢ π ⁢ sin ⁢ 2 ⁢ π ⁡ ( r - R ) NR 0 - R 0 ] , } ⁢ R 0 ≤ r ≤ N ⁢   ⁢ R 0 C 1 ≈ - C 2 2 ⁢ R 2 , C 3 ≈ C 2 R 2 ,
    and then the trajectories of the first system of trajectories are rendered a shape of helices in accordance with the dependencies: Z 1 ⁢ i ⁡ ( r ) = C 4 ⁢ i / r 2 + C 5 ⁢ i ⁡ [ r - R N ⁢   ⁢ R 0 - R - 1 2 ⁢ π ⁢ sin ⁢ 2 ⁢ π ⁡ ( r - R ) N ⁢   ⁢ R 0 - R 0 ] , φ 1 ⁢ i ⁡ ( r ) = φ 10 ⁢ i + v φ1 ⁡ ( R ) 2 ⁢ v r1 ⁡ ( R ) ⁢ R 2 R 0 2 ⁡ [ R 0 2 r 2 - 1 + ( r - R ) 2 2 ⁢ R 0 ⁡ ( R 0 - R ) - 1 2 + R 2 ⁢ R 0 ] , } ⁢ R ≤ r ≤ N ⁢   ⁢ R 0 0 < C 4 ⁢ i < C 2 , C 5 ⁢ i = C 3 ⁢ • ⁢   ⁢ C 4 ⁢ i / C 2 ,

The second system of trajectories results from the interaction between the directed flow and the concave surface of revolution, and in this case the trajectories of the second system of trajectories, which are adjacent to this surface of revolution, are rendered a shape in accordance with the dependencies given below: Z 3 ⁡ ( r ) = C 6 / r 2 + C 7 ⁡ [ r - R NR 0 - R - 1 2 ⁢ π ⁢ sin ⁢ 2 ⁢ π ⁡ ( r - R ) NR 0 - R ] , R 0 ≤ r ≤ NR 0 C 6 ≥ C 2 , C 7 ≥ C 3 ,

The trajectories of the second system of trajectories are rendered in a shape of helices in compliance with the dependencies: Z 2 ⁢ i ⁡ ( r ) = C 8 ⁢ i / r 2 + C 9 ⁢ i ⁡ [ r - R N ⁢   ⁢ R 0 - R - 1 2 ⁢ π ⁢ sin ⁢ 2 ⁢ π ⁡ ( r - R ) N ⁢   ⁢ R 0 - R 0 ] , φ 2 ⁢ i ⁡ ( r ) = φ 20 ⁢ i + v φ2 ⁡ ( R ) 2 ⁢ v r2 ⁡ ( R ) ⁢ R 2 R 0 2 ⁡ [ R 0 2 r 2 - 1 + ( r - R ) 2 2 ⁢ R 0 ⁡ ( R 0 - R ) - 1 2 + R 2 ⁢ R 0 ] , } ⁢ R ≤ r ≤ R 0 C 8 ⁢ i > C 8 , C 9 ⁢ i > C 7 ,
where:

• r, φ, z represent cylindrical coordinates, in which axis Z coincides with the axis of the axissymmetric volume, in which the vortex flow is generated;
• R₀ denotes the distance from the axis of the axissymmetric volume to the beginning of the helical trajectories; R ≈ 1 5 ⁢ R 0
  is the radius of the axissymmetric volume in the zone where the formed vortex flow runs out of the said volume;
• NR₀ denotes the distance from the axis of axissymmetric volume to the beginning of the convergent surface of revolution, N≧2;
• C₂ is a constant value connected with height Z and radius R of the axissymmetric volume: C 2 ≈ ZR 2 2 ;
• C₁, C₃ are constants, expressed through constants C₂;
• C_4i, C_5i are constants, which vary within the above indicated ranges;
• φ_10i, φ_20i are values of angle φ at the beginning of the i-th helical trajectory of the first and second systems accordingly; v ϕ ⁢   ⁢ 1 ⁡ ( R ) v r ⁢   ⁢ 1 ⁡ ( R ) , v ϕ ⁢   ⁢ 2 ⁡ ( R ) v r ⁢   ⁢ 2 ⁡ ( R )
  are relations of rotational and radial velocity components at radius R for the first and second systems of helical trajectories accordingly,
• C₆, C₇ are constants, which vary within the above indicated ranges;
• C_8i<ZR² represents a constant, which does not exceed the product of height Z of the axissymmetric volume, in which the vortex flow is generated, by the square of its radius R; and
• C_9i≦Z is a constant, which is less than the height of the axissymmetric volume, in which the vortex flow is generated or is of the same order with the height.

According to an advantageous development of the invention, the fluid guiding structure may be at least partly embedded into ground. Even more advantageously, the fluid guiding structure may be at least partly embedded into a mountain or hill. It is particular advantageous to embed the fluid guiding structure near or at the ridge of a mountain or hill. In this way, the mountain or hill is used as a supporting structure and heavy free-standing construction may be avoided. Furthermore, the mountain further increases the wind velocity. Accordingly, the continuous medium flow having enhanced flow velocity is collected by the inlet chamber being arranged near or at the ridge of a hill or mountain on top of the ground.