WO2012055378A1

WO2012055378A1 - Wind-turbine rotor

Info

Publication number: WO2012055378A1
Application number: PCT/CR2010/000002
Authority: WO
Inventors: Carlos Acosta Nassar
Original assignee: Universidad De Costa Rica
Priority date: 2010-10-28
Filing date: 2010-10-28
Publication date: 2012-05-03

Abstract

A windmill-style wind-turbine rotor, the axis of which is substantially aligned with the wind direction, characterized in that the blades thereof have a truncated conical surface shape with curved edges approximately perpendicular to the generator of said surface.

Description

WIND TURBINE ROTOR

Technology sector

The present invention relates to the sector of rotors for wind turbines whose axis is substantially aligned with the wind direction (International Classification F03D1 / 06), more specifically with the shape of said rotors (International Classification F03D1 / 06B).

Background of the invention

Wind turbines are classified into two main classes: those in which air flows perpendicular to the axis of the turbine and those in which it flows parallel to the axis. Among those of flow perpendicular to the axis, the majority are of vertical axis although they also develop with horizontal axis. Those of parallel flow to the axis are generally of horizontal axis since in that direction the wind flows. However, in some cases, if air arrives through a pipeline, the turbine can be installed with its axis in an upright position.

The field of interest of the present invention is that of wind turbines with air flowing parallel to the axis (except slight deviations that may occur in order to regulate the operation of the turbine). Within this field, the turbines of the propeller type and those of the windmill type are distinguished, among others.

Propeller type turbines operate at relatively high speeds, with low torque and have few blades (typically six or less, mostly only two or three). In addition, these blades typically have an airplane wing-shaped section and leave a significant open area between them facing the wind. In many cases the turbines have devices for pivoting the blades in order to change their angle to the wind direction.

Compared to those of the propeller type, windmill type turbines operate at relatively lower speeds, with lower torque and have a larger number of blades. Although these blades can also have a wing-shaped section, they tend to be thinner and are mostly formed from sheets, either flat, single curvature (mostly) or double curvature. It is also more frequent that the blades remain fixed in the rotor, although there are versions with adjustable position blades.

Propeller type turbines are the most used in electricity generation, because they operate at speeds closer to those of electric generators. In addition, the larger they are, the more important is the reduction of material in relation to the power generated, which is achieved with fewer blades rotating at a higher speed.

In the generation of electricity with small turbines, it is feasible to use both propeller and windmill type turbines. In this range, windmills have the advantage that, by generating greater torque and operating at a lower speed, they are able to take advantage of lower speed winds, in which a propeller type turbine would usually stop. This in turn allows the turbines to be placed at a lower height, with the consequent savings in infrastructure, or in places that are not particularly favorable due to the available wind speed. In addition, by operating at a lower speed, windmills produce less noise. Windmill type turbines date back several centuries. Some of the patents related to improvements in the state of the art of windmill type turbines are reviewed below. In US Patent 237,467 of 1881 the basic form of a windmill is already shown with its central hub in the form of a circular plate, a plurality of blades and a peripheral ring. The rear vane is already incorporated in order to align the shaft with the wind. In this case the transmission is vertical of alternative movement (up and down), which is particularly appropriate in windmills due to its low speed.

U.S. Patent 457,168 of 1891 reflects the use of one or more reinforcing rings and also the implementation of blades formed from thin and curved sheets.

U.S. Patent 1,467,227 of 1921 shows the search for blades that are not only formed from curved surfaces or with variation between their angle of entry and exit, but also have curved edges, so that said blades extend forming a slight spiral. U.S. Patent 2,417,022 of 1945 shows the use of conical gears in order to transmit power in the form of rotary motion, through a vertical transmission bar. This expands the scope of the turbines and would make them suitable, for example, to move an electric generator located near the base of the tower.

U.S. patents 4,086,498 of 1978 and U.S. 4,140,433 of 1979 show a type of turbine, which while retaining traces of the windmill type design, is specifically designed for the generation of electricity. In addition the rotor of this turbine and its static parts show the use of conical, or approximately conical, surfaces to guide the wind towards the blades and to prevent the centrifugal flow escaping from the periphery of the rotor.

U.S. Patent 5,910,688 of 1999 continues to show, in relatively recent dates, the search for curved blades from thin sheets. In this case a helical blade, which not only has a curved surface but also its edges are curved and its angle of entry and exit varies according to the distance to the center of the rotor.

Although in the field of wind turbines of the propeller type, great advances have been made in their aerodynamic form, as can be seen in the cited patents, the same does not happen in windmill type turbines. In this case, greater emphasis has been placed on the constructive aspect and there are also important limitations regarding the geometry of the blades, because the most economical thing is to build them from flat or slightly curved sheets, whose thickness is constant.

It is therefore necessary to develop a windmill type turbine rotor, whose blades can always be manufactured from blades, but with a shape that allows the use of wind energy in the most efficient way possible. Brief description of the drawings

The included drawings show the best way to carry out the invention as well as examples of several other possible embodiments of the invention.

Figure 1 shows an overview of a typical horizontal axis turbine aligned with the wind direction, showing its main components and a possible embodiment of the rotor object of the present invention.

Figure 2 shows another general view of a typical horizontal axis turbine aligned with the wind direction, mainly showing a possible embodiment of the rotor object of the present invention.

Figure 3 shows a possible embodiment of the rotor object of the present invention

Figure 4 shows the generation of a conical surface and how it is trimmed from it the shape of a possible blade for the rotor object of the present invention.

Description

The present invention provides a wind turbine rotor of the type whose axis is substantially aligned with the wind direction. Said rotor includes a central hub connected to said shaft, from which a plurality of blades extend. It also has a peripheral ring surrounding the ends of said blades and optionally a reinforcement ring that crosses all the blades approximately halfway through its radial extension.

The main feature of this rotor is that its blades are shaped like a conical surface, trimmed in such a way that the edge where the wind strikes and the edge where the wind comes out are approximately perpendicular to any straight line that is drawn from the vertex of said conical surface to any point of intersection with said edges.

Detailed description

The area of application of this invention is that of rotors for wind turbines with a shaft substantially alienated with wind direction. In a preferred configuration, a rotor (1) is coupled to a shaft (2) that connects it with the rest of the components in a central body (3). Said central body (3) pivots on a tower (4) in order to keep the shaft (2) aligned with the wind direction. In order to align the axis with the wind direction, the turbine has a tail vane (5) attached to the central body (3) in the opposite location to the rotor (1).

This does not exclude the possibility of locating the rotor in a different turbine configuration, for example, behind the main body. In this case, a vane is not required, but the operation and durability of the rotor can be affected by turbulence generated around the body central (3) and tower (4). Another possibility is to install the rotor in a frame to fix to the roof of a building or to assemble a set of several small turbines forming a wall.

The central body (3) houses a series of components, for example, a gearbox to direct the mechanical energy through a vertical transmission bar to a generator located near the base of the tower, one or several generators that would enter to operate according to the power that captures the rotor, a governor and other control devices typical of wind turbines. It can also accommodate a generator, its corresponding gearbox to adapt the speed of the shaft (2) to the speed of the generator, as well as various types of electrical, electronic or mechanical controllers.

In the preferred configuration of the rotor (1), it is composed of a central hub (6) coupled directly to the shaft (3), a set of blades (7), a peripheral ring (8) and a reinforcement ring (9) , all firmly attached to each other.

The central hub (6) extends radially in the form of a circular plate with a diameter and thickness large enough to provide sufficient area for fixing the blades (7). This does not exclude the possibility of using a different configuration cube as long as said blades can be attached to it.

The blades (7) extend radially from the central hub (6) each forming a slight spiral. These blades have the shape of a conical surface (10) cut out in such a way that its edge where the wind enters (11) and its edge where the wind leaves (12) are approximately perpendicular to the generatrix (13) of said surface conical (10) at the point where said generatrix (13) intersects them when turning around its axis (14). This is the same as saying that any straight line drawn from the vertex (15) of the conical surface (10) will intersect the leading edge (11) and the leading edge (12) of the blade (7) approximately perpendicularly . This form of blade allows the possibility of modulating the angle of attack and the angle of wind output, as well as the flow of wind through the rotor in such a way that a minimum of turbulence is produced and the greatest possible energy is captured.

In a preferred configuration, the peripheral ring (8) is cylindrical with its axis coinciding with the axis (2) of the turbine and surrounds the blades (7) extending axially to cover the axial extent of said blades (7). Said peripheral ring (8) fulfills three functions: providing rigidity to the assembly, eliminating turbulence losses at the tips of the blades (7) and preventing energy leaks in the form of centrifugal flow. The reinforcement ring (9) is fixedly connected with all the blades (7) approximately halfway through its radial extension and provides additional rigidity.

Finally, in the preferred configuration an ogive (16) is fixed approximately conically in front of the central hub (6). The axis of said warhead (16) coincides with the axis of the turbine (2), its vertex (17) points in the opposite direction to the wind and its base (18) covers at least partially the central hub (6). This warhead (16) receives the air flow that would otherwise collide with the central hub (6) and directs it gently towards the blades (7). This description does not exclude the possibility of variants in the design that maintain the basic spirit of the invention, such as a peripheral ring (8) of smaller dimensions, vanes (7) extending beyond the peripheral ring (8), variations in the orientation and curvature of the blades (7), reduction or elimination of the reinforcement ring (9), central hub (6) aerodynamically so that the warhead (16) can be dispensed with.

Claims

1. A rotor for a wind turbine whose axis is substantially aligned with the direction of the wind, which includes a central hub connected to said axis, from which a plurality of blades and a peripheral ring surrounding the ends of said blades extend, characterized in that each of said blades has a conical surface shape, cut out in such a way that the edge where the wind strikes and the edge where the wind comes out are approximately perpendicular to any straight line that is drawn from the vertex of said conical surface to any point of intersection with said edges.

2. The rotor of claim 1, characterized in that it has a reinforcing ring that crosses all the blades approximately halfway through its radial extension.