SHIELDED VERTICAL AXIS TURBINE
Field of the Invention
This invention relates to turbines and, more specifically, to a vertical axis wind turbine that is capable of more efficiently converting wind energy into rotational energy than the designs known from the prior art.
Background to the Invention
Horizontal axis wind turbines and vertical axis wind turbines are both used to generate power using wind energy. Horizontal axis wind turbines with rotors typically having three blades are commonly arranged as fields for the generation of electricity.
Vertical axis wind turbines such as, for example, the Savonius and Darrieus designs are used to a lesser extent as they do not convert wind energy to power efficiently enough to be commercially useful, although they are more reliable than horizontal axis turbines.
The inventor has developed a new vertical axis turbine that he believes converts energy from a linear fluid flow to rotational energy efficiently enough to be commercially useful. The term "vertical axis turbine" is to be understood a describing a turbine in which the fluid flow is perpendicular to the rotational axis of the turbine.
Summary of the Invention
According to the invention there is provided a vertical axis turbine including:- a rotational axis defined by a shaft; a plurality of vanes of substantially equal shape and angular orientation, the vanes being arranged in a circular configuration in a spaced apart, fixed relationship relative to the centrally located shaft; and - a fluid flow directing means arranged along the side of the turbine which in use is exposed to fluid flow resulting in no or an undesired rotational force being imparted to the shaft and which fluid flow directing means redirects at least a portion of said fluid flow so as to aid rotation of the shaft.
The vanes may extend between mounting formations arranged along the shaft. The 5 mounting formations may be configured to retain free ends of the vanes. The mounting formations may be in the form of plates which may be circular or may be any other suitable shape when viewed in plan.
The shaft may extend beyond one or both mounting formations so as to define a drive shaft 0 for transmitting rotational energy to a conventional means for utilizing rotational energy to generate electricity such as, for example, a generator.
The vanes may be located equidistant from the shaft. The spacing between successive vanes may be equidistant or may be varied to achieve a reduction of noise and/ or vibration 15 created during rotation of the shaft.
The turbine may be provided with two or more vanes. The number of vanes provided may vary in accordance with the dimensions of the turbine, wherein a larger number of vanes is required as the diameter of the turbine increases. .0
The number of vanes may furthermore be selected in accordance with the distance that the vanes are spaced apart from the shaft to achieve optimum performance of the turbine.
The shape of each vane may be curved in cross-section, it may be linear, or it may bent at !5 intervals to approximate a curve. The thickness of the vanes may be uniform along its cross- section. Alternatively, the vanes may be in the form of conventional turbine blades which are not of uniform thickness or cross-section.
The angular orientation of the vanes may be chosen in accordance with the shape and iO spacing of the vanes to achieve optimum performance of the turbine. The vanes, shaft, and mounting formations may define a rotor of the turbine.
The vanes may be reinforced by one or more stiffening means located along the length of the shaft. The stiffening means may be in the form of a retaining formation having openings or 5 receiving formations through which the vanes pass and which retaining formation inhibits excessive flexing of the vanes in use. Alternatively, the stiffening means may be in the form of struts extending from the shaft to the vanes.
The vanes, shaft, mounting formations and stiffening means may be manufactured from any 0 suitable material such as a metal or metal alloy or a synthetic plastics material and may form an integral unit.
In the preferred embodiment shown in Figure 10, the diameter of the rotor is 600mm, the length of each vane is 2000mm and the rotor includes 28 vanes. 5
The fluid flow directing means may be in the form of one or more stators extending circumferentially around some vanes of the rotor with the longitudinal axes of the stators arranged parallel to the shaft. The stators typically extend around about half of the circumference of the rotor. !0
Surfaces of the stators located proximate the rotor may be curved complementally to the curvature of the rotor.
Surfaces of the stators exposed to the fluid flow (exterior surfaces) may be curved so as to »5 redirect the fluid flow towards fluid flow passages which channel a portion of the flow towards the vanes of the turbine to achieve the desired rotation of the shaft and to direct a portion of the flow through the center of the rotor so that it does not act on the vanes.
The cross-sectional shape of each stator is determined by its orientation relative to the !0 direction of fluid flow. The cross-sectional shape of each stator may be unique. The fluid flow passages may be defined by surfaces of adjacent stators. The fluid flow passages may narrow towards the vanes so as to increase the velocity of fluid when it flows through the passages towards the vanes.
The stators may furthermore define one or more fluid flow passages for aiding in expulsion of fluid from the turbine. These passages may be located at the leeward side of the turbine.
The stators may both serve to redirect a portion of the fluid flow towards the vanes as well as to shield the vanes from fluid flow that would otherwise result in no or an undesired rotational force being imparted to the shaft.
The shape of the stators in combination with the arrangement of the vanes and shaft may selected to inhibit static pools of fluid forming in the turbine in use. The fluid flow into as well as out of the turbine may be aided by the specific arrangement of the stators, vanes and shaft of the present invention.
The stators may be supported by and extend between a base and a ceiling. The mounting formations of the vanes may be spaced apart from the base and ceiling and may be connected thereto via bearings that permit rotation of the rotor relative to said base and ceiling.
The fluid flow acting on the turbine in use may be a gas or a vapour, i.e. the turbine may be a wind turbine.
In an alternative embodiment of the invention the rotation of the rotor, as opposed to the rotation of the shaft, may be converted into electrical energy. This may be achieved by attaching magnets to the vanes and/or to the mounting formations of the rotor. The spacing between the magnets may be substantially even.
Induction coils may be provided around the rotor so that rotation of the rotor and thereby the magnets, induces an electrical current in the coils. The distance between the coils and the magnets may be variable by moving the coils towards or away from the rotor, thereby enabling a user to select the magnitude of the induced current. The coils may be located in the stators.
In use, the shaft of the turbine may preferably be orientated in a substantially vertical relationship to the ground although it may in particular cases be desirable for it to be orientated substantially horizontal to the ground.
In use, when a strong fluid flow is acting on the turbine, the turbine may be rotated so that exterior surfaces of the stators face directly into the direction of the fluid flow, thereby shielding the vanes and inhibiting damage to the turbine. In addition, the exterior surfaces of the stators may be used to display advertisements or logos thereon.
Two or more rotors may be stacked and share a common shaft or axis of rotation. In this configuration, individual rotors can readily be removed for maintenance purposes. The rotors may be stacked onto a raised base.
Detailed Description of the Invention
The invention will now be described by way of the following non-limiting example with reference to the accompanying drawings.
In the drawings:-
5 Figure 1 shows a perspective view of a portion of a turbine in accordance with the present invention;
Figure 2 shows an elevated view of Figure 1 ;
) Figure 3 shows a cross-sectional view of Figure 1 along lines B-B indicated in Figure 2; Figure 4 shows a perspective view of a single vane of the turbine;
Figure 5 shows a cross-sectional view of a turbine in accordance with the present invention;
Figure 6 shows a cross-sectional view of a portion of a turbine in accordance with the present invention wherein the fluid flow through the turbine is indicated during rotation of the shaft;
Figure 7 shows a perspective view of a portion of a turbine in accordance with the present invention including a stiffening means;
Figure 8 shows a cross-sectional view of a portion of a turbine in accordance with the present invention wherein the fluid flow through the turbine is indicated whilst the shaft is stationary;
Figure 9 shows an elevated view of a tower and a support base on which a plurality of are mounted in a stacked configuration;
Figure 10 shows a cross-sectional view of a portion of a preferred embodiment of a turbine in accordance with the present invention wherein the fluid flow through the turbine is indicated during rotation of the shaft; and )
Figure 11 shows a cross-sectional view of the turbine of Figure 5 wherein magnets are provided on the vanes and induction coils are provided in the stators of the turbine.
In the drawings, reference numeral 10 generally indicates a vertical axis turbine in: accordance with the present invention.
The vertical axis turbine 10 includes a rotational axis defined by a shaft 12 and a plurality of vanes 14 of substantially equal shape and angular orientation, the vanes 14 being arranged in a circular configuration in a spaced apart, fixed relationship relative to the centrally located shaft 12. A fluid flow directing means 16 is arranged along the side of the turbine 20 which in use is exposed to fluid flow resulting in no or an undesired rotational force being imparted to the shaft 12 and which fluid flow directing means 16 redirects at least a portion of said fluid flow so as to aid rotation of the shaft 12 as can be seen in Figures 6, 8, and 10.
The vanes 14 extend between mounting formations arranged along the shaft 12. The mounting formations are configured to retain free ends of the vanes 14 and are in the form of circular plates 18.1 and 18.2.
In one embodiment, the shaft 12 extend beyond one or both plates 18.1 and 18.2 so as to define a drive shaft for transmitting rotational energy to a conventional means for utilizing rotational energy to generate electricity such as, for example, a generator (not shown).
The vanes 14 are located equidistant from the shaft 12. The spacing between successive vanes 14 is typically equidistant as shown in the Figures. This distance can varied to achieve a reduction of noise and/ or vibration created during rotation of the shaft 12.
The turbine 10 is typically provided with a minimum of twelve vanes 14. The number of vanes provided varies in accordance with the dimensions of the turbine 10, wherein a larger number of vanes 14 is required as the diameter of the turbine 10 increases as shown in Figure 10.
The number of vanes 14 is furthermore selected in accordance with the distance that the vanes 14 are spaced apart from the shaft 12 to achieve optimum performance of the turbine 10.
The shape of each vane 14 can be curved in cross-section, it may be linear, or it may bent at intervals to approximate a curve as shown in the Figures. The thickness of the vanes 14 is typically uniform along its cross-section. It is however to be appreciated, that the vanes 14 can also be in the form of conventional turbine blades which are not of uniform thickness or cross-section. W 2
The angular orientation of the vanes 14 is chosen in accordance with the shape and spacing . of the vanes 14 to achieve optimum performance of the turbine 10.
The vanes 14, shaft 12, and plates 18.1 and 18.2 define a rotor of the turbine 10.
In one embodiment of the invention, the diameter of the rotor is 620mm, the length of each vane 14 is 2000mm and the rotor includes 28 vanes 14.
The vanes 14 are reinforced by one or more stiffening means located along the length of the shaft 12. The stiffening means is in the form of a retaining formation 22 (see Figure 7) having receiving formations through which the vanes 14 pass and which retaining formation 22 inhibits excessive flexing of the vanes 14 in use.
The vanes 14, shaft 12, plates 18.1 and 18.2 and retaining formation 22 may be manufactured from any suitable material such as a metal or metal alloy or a synthetic plastics material and typically form an integral unit. However, the vanes 14 could also be manufactured from a light, extruded alloy.
The fluid flow directing means 16 is in the form of one or more stators 24 extending ) circumferentially around some vanes 14 of the rotor 20 with the longitudinal axes of the stators 24 arranged parallel to the shaft 12. The stators 24 typically extend around about half of the circumference of the rotor 20 as can be seen in Figures 5,6,8,10, and 11.
Surfaces of the stators 24 located proximate the rotor 20 are curved complementally to the ; curvature of the rotor 20.
Surfaces of the stators exposed to the fluid flow 26 (exterior surfaces) are curved so as to redirect the fluid flow 26 towards fluid flow passages 28 which channel a portion of the flow 26 towards the vanes 14 of the turbine 10 to achieve the desired rotation of the shaft 12 and to direct a portion of the flow 26 through the center of the rotor 20 so that it does not act on the vanes 14. The cross-sectional shape of each stator 24 is determined by its orientation relative to the direction of fluid flow 30. The cross-sectional shape of each stator 24 is unique.
The fluid flow passages 28 are defined by surfaces of adjacent stators 24. The fluid flow 5 passages 28 narrow towards the vanes 14 so as to increase the velocity of fluid when it flows through the passages 28 towards the vanes 14.
In the embodiment shown in Figure 10, the stators 24 furthermore define a fluid flow passage 32 for aiding in expulsion of fluid from the turbine 10. This passage 32 is located at the [0 leeward side of the turbine 10.
The stators 24 serve to redirect a portion of the fluid flow 26 towards the vanes 14 as well as to shield the vanes 14 from fluid flow 26 that would otherwise result in no or an undesired rotational force being imparted to the shaft 12.
.5
The shape of the stators 24 in combination with the arrangement of the vanes 14 and shaft 12 are selected to inhibit static pools of fluid forming in the turbine 10 in use. The fluid flow into as well as out of the turbine 10 is aided by the specific arrangement of the stators 24, vanes 14 and shaft 12 of the present invention.
:0
In addition, when subjected to fluid flow, the pressure exerted on the turbine 10 in the direction of the fluid flow 30 is higher than the pressure on the leeward side of the turbine 10. This pressure differential aids in the expulsion of fluid from the turbine 10.
5 The stators 24 are supported by and extend between a base 25 and a ceiling (not shown). The plates 18.1 and 18.2 are spaced apart from the base 25 and ceiling and are connected thereto via bearings that permit rotation of the rotor 20 relative to said base 25 and ceiling.
The fluid flow acting on the turbine in use may be a gas or a vapour, i.e. the turbine may be a 0 wind turbine. In the embodiment shown in Figure 11 , the rotation of the rotor 20, as opposed to the rotation of the shaft 12, is converted into electrical energy. This is achieved by attaching magnets 34 to the vanes 14 of the rotor 20. The spacing between the magnets 34 is substantially even.
Induction coils 36 are provided around a portion of the rotor 20 so that rotation of the rotor 20 and thereby the magnets 34, induces an electrical current in the coils 36. The distance between the coils 36 and the magnets 34 is variable by moving the coils 36 towards or away from the rotor 20, thereby enabling a user to select the magnitude of the induced current. In the embodiment shown, the coils 36 are located in the stators 24.
In use, the shaft 12 of the turbine 10 is preferably be orientated in a substantially vertical relationship to the ground as shown in Figure 1.
In use, when a strong fluid flow is acting on the turbine 10, the turbine 10 can rotated so that exterior surfaces of the stators 24 face directly into the direction of the fluid flow, thereby shielding the vanes 14 and inhibiting damage to the turbine 10. In addition, the exterior surfaces of the stators 24 can be used to display advertisements or logos thereon.
Referring now to Figure 9, three turbines 10 have been stacked and share a common shaft 12 or axis of rotation. In this configuration, individual rotors 20 can readily be removed for maintenance purposes. The rotors 20 are stacked onto a raised base 38.
It is to be appreciated, that the invention is not limited to any specific embodiment as hereinbefore generally described or illustrated.