Increased - efficiency rotor on a vertical axis of rotation

Abstract

Increased - efficiency rotor on a vertical axis of Rotation consists of two coaxial discs (1) permanently connected by rotor blades (2) and an axial profile (3) with the number of side walls equal to the number of blades (2). The blades (2) form vertical, narrowing flow gaps (4) with the edge of the axial profile (3).

Description

[0001] Increased - Efficiency Rotor on a

[0002] Vertical Axis of Rotation

[0003] The subject of the invention is an increased-efficiency rotor on a vertical Axis of Rotation for use in wind power plants with a vertical axis of rotation. This rotor, either alone or in combination with a system of guide vanes, is used to convert the kinetic energy of the wind into the rotational energy of the rotor, which allows it to be used with devices for generating electrical energy.

[0004] Wind power plants with a vertical axis of rotation generally have lower efficiency in converting wind energy into electrical energy compared to the commonly used horizontal axis power plants. Nevertheless, they also have numerous advantages, such as simple construction, ability to start at low wind speeds regardless of wind direction, and quiet and safe operation.

[0005] The limitation of these solutions is that one half of the horizontal cross-section operates by rotating in the direction of the wind, while the other half, rotating against the wind direction, acts as a drag. Wind turbines with vertical axis rotors are known from patent descriptions PL233605B1 , PL235275B1 , PL236244B1 , PL217317B1 , as well as US20100308597A1 , EP2514964A1 , and many others.

[0006] Vertical axis wind turbines equipped with flexible or variable geometry or surface blade systems are also known. These systems increase the surface area of the half of the horizontal cross-section of the rotor rotating in the direction of the wind while simultaneously reducing the wind's impact on the half rotating against the wind direction, thereby improving the efficiency of these rotors. Such and similar solutions are known from patent descriptions PL241530B1 , PL242967B1 , PL389245A1 , PL442363A1 , EP2321529B1 , and many others.

[0007] A proposal for a rotor with variable blade geometry is known from the Japanese application JP2008175176 A, where the inner ends of the blades are movable and adjusted depending on the rotational speed. The described aim was to improve the startup characteristics and limit the rotational speed during operation in strong winds. The current state of knowledge describes solutions with low efficiency and performance of vertical axis wind turbines compared to horizontal axis turbines. The objective of the invention is to improve the parameters of the vertical axis wind turbine. Additionally, it is desirable to use low and medium wind speeds for efficient electricity production. There is a need for greater utilization of the kinetic energy of the airflow acting on vertical axis wind turbines compared to previously disclosed solutions.

[0008] The increased-efficiency vertical axis rotor features two coaxial discs connected by vertical blades. Centrally mounted between the blades is an axial profile with a cross-section in the shape of a regular polygon, with the center of the polygon coinciding with the center of the discs and forming the rotor's axis of rotation. The number of blades and the number of sides of the centrally mounted axial profile are equal. The blades are attached to the discs in such a way that the edge of the arc of each blade is close to the edge of the discs, while the edge of the straight part is close to the side of the axial profile, creating a flow gap with it. It is evident to a skilled person that the function of the discs can also be provided by domes that are segments of a sphere or cones, facing each other with their apexes.

[0009] By narrowing this gap, the airflow is further accelerated, causing the air to hit the subsequent rotor blades at increased speeds. This significantly enhances the conversion of the wind's kinetic energy compared to other known designs.

[0010] Preferably, the number of blades and the number of sides of the centrally mounted axial profile range from three to six.

[0011] Preferably, the blades and the axial profile are placed in cutouts in the discs that match the shape.

[0012] Preferably, the cross-sectional shape of the blade is a rectangle with rounded edges, transitioning on one side into an arc that is a segment equal to 1 / 4 of a circle with a diameter equal to 1 / 5 of the disc's diameter.

[0013] The ratio between the diameter of the discs and the diameter of the circle circumscribed around the regular polygon forming the cross-section of the axial profile is preferably between 4:1 and 5:1 . Preferably, the ratio between the diameter of the discs and the width of the gaps formed by the blades and the sides of the axial profile at their narrowest point is between 10:1 and 12:1 .

[0014] The mounting angle of the straight part of the blade in cross-section relative to the profile's side is preferably between 12° and 15°.

[0015] The increased-efficiency rotor allows the airflow to pass between the working blade and the axial profile, directing the flow in a desired manner, which enhances the efficiency of converting the wind's kinetic energy into the rotor's rotational energy. The centrally mounted axial profile narrows the wind stream hitting the subsequent rotor blades vertically, and when domes or cones are used, also horizontally. This increases the wind speed impacting the subsequent rotor blades compared to the wind speed outside the rotor due to the narrowing gap between the profile and the rotor blade. As a result, the invention achieves increased efficiency and energy output.

[0016] Thanks to the symmetrical arrangement of the blades, the increased-efficiency rotor does not require adjustment relative to the wind direction. It is a safe and quiet construction. Due to its specific design, the rotor cannot accelerate to excessive speeds, allowing for continuous operation even during strong and very strong winds. Wind power plants using this described design can utilize low and medium wind speeds to a significantly greater extent than other types of turbines. This is particularly important in areas where wind energy harvesting has not been economically viable until now.

[0017] The subject of the invention is illustrated in the drawings, where Fig. 1 shows an axonometric view of the rotor with three blades and an axial profile with a crosssection in the shape of an equilateral triangle, Fig. 2 shows a top view of the rotor without the upper disc, with three blades and an axial profile with a cross-section in the shape of an equilateral triangle, Fig. 3 shows an axonometric view of the rotor with four blades and an axial profile with a cross-section in the shape of a square, Fig. 4 shows a top view of the rotor without the upper disc, with four blades and an axial profile with a cross-section in the shape of a square, Fig. 5 shows a top view of the rotor without the upper disc, with five blades and an axial profile with a cross-section in the shape of a regular pentagon, Fig. 6 shows a top view of the rotor without the upper disc, with six blades and an axial profile with a cross-section in the shape of a regular hexagon, Fig. 7 shows an axonometric view of a rotor blade, Fig. 8 presents the measurement results obtained in the graph, which are included in the Table.

[0018] Example 1 : An increased-efficiency vertical axis rotor was produced using 3D printing technology. The rotor consisted of two coaxial discs 1 placed parallel to each other with flat surfaces. The diameter of each disc 1 was 16 cm, and the distance between the discs 1 was 10 cm. The height of both the rotor blades 2 and the axial profile 3 was also 10 cm. The discs 1 were connected by four blades 2 and a profile 3 with a crosssection in the shape of a square, sharing a common center 6 with the discs 1 and having external dimensions of 3.2 x 3.2 cm. The blades 2 were shaped like rectangular plates, with one side ending in a curve shaped as a vertical segment of 1 / 4 of the surface of a cylinder with a diameter of 3.2 cm. The straight parts of the blades 2 were mounted along the walls of the axial profile 3 and aligned vertically with the edges connecting its walls, while the curved parts were aligned with the edges of the discs 1. The blades 2 and the profile 3 were perpendicularly attached to the discs 1 in such a way that vertical flow gaps 4 were formed between the blades 2 and the walls of the profile 3.

[0019] The narrowest width of the flow gaps 4 created by the flat parts of the blades 2 and the walls of the profile 3 was 1 cm, and the mounting angle 5 of the straight parts of the blades 2 relative to the walls of the profile 3 was 12°. For the purpose of taking measurements, the rotor axis 7 was stabilized horizontally with magnetic bearings and vertically with needle bearings.

[0020] Example 2: For comparison purposes, an experiment was conducted to measure the parameters of a simple Savonius rotor with the same vertical cross-section dimensions as in Example 1 , featuring two blades attached to flat discs. The rotational speed measurements were taken under identical conditions as in Example 1 .

[0021] The results obtained in the above examples are summarized in the Table. Table:

Claims

Claims1 . An increased - efficiency rotor on a vertical axis of rotation featuring two coaxial discs connected by vertical blades, characterized in that an axial profile (3) with a cross-section in the shape of a regular polygon is centrally mounted between the blades (2), while the center (6) of the regular polygon (3) is common to the discs (1 ) and the profile (3), forming the rotor's (7) axis of rotation, and additionally, the number of blades (2) and the number of sides of the centrally mounted axial profile (3) are equal, while the blades (2) are attached to the discs (1 ) such that the arc edge of each blade is close to the edges of the discs (1 ), while the straight part is close to the wall of the axial profile (3), creating a flow gap (4) with it that narrows in the direction of the regular polygon.

2. The rotor according to claim 1 , characterized in that the number of blades (2) and the number of sides of the centrally mounted axial profile (3) ranges from three to six.

3. The rotor according to claim 1 or 2, characterized in that the blades (2) and the axial profile (3) are placed in cutouts in the discs (1 ) that match the shape and size of the blades (2) and the profile (3), and are then connected to the discs (1 ).

4. The rotor according to any of the preceding claims, characterized in that the cross-sectional shape of the blade (2) is a rectangle with rounded edges, transitioning on one side into an arc that is a segment equal to 1 / 4 of a circle with a diameter equal to 1 / 5 of the disc's (1 ) diameter.

5. The rotor according to any of the preceding claims, characterized in that the ratio between the diameter of the discs (1 ) and the diameter of the circle circumscribed around the regular polygon forming the cross-section of the axial profile (3) is between 4:1 and 5:1.

6. The rotor according to any of the preceding claims, characterized in that the ratio between the diameter of the discs (1 ) and the width of the gaps (4) at their narrowest point is between 10:1 and 12:1.

7. The rotor according to any of the preceding claims, characterized in that the mounting angle (5) of the straight part of the blade (2) in cross-section relative to the wall of the profile (3) is between 12° and 15°.

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