CA2532734A1 - Economic low-head hydro and tidal power turbine - Google Patents
Economic low-head hydro and tidal power turbine Download PDFInfo
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- CA2532734A1 CA2532734A1 CA002532734A CA2532734A CA2532734A1 CA 2532734 A1 CA2532734 A1 CA 2532734A1 CA 002532734 A CA002532734 A CA 002532734A CA 2532734 A CA2532734 A CA 2532734A CA 2532734 A1 CA2532734 A1 CA 2532734A1
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F03—MACHINES OR ENGINES FOR LIQUIDS; WIND, SPRING, OR WEIGHT MOTORS; PRODUCING MECHANICAL POWER OR A REACTIVE PROPULSIVE THRUST, NOT OTHERWISE PROVIDED FOR
- F03B—MACHINES OR ENGINES FOR LIQUIDS
- F03B17/00—Other machines or engines
- F03B17/06—Other machines or engines using liquid flow with predominantly kinetic energy conversion, e.g. of swinging-flap type, "run-of-river", "ultra-low head"
- F03B17/062—Other machines or engines using liquid flow with predominantly kinetic energy conversion, e.g. of swinging-flap type, "run-of-river", "ultra-low head" with rotation axis substantially at right angle to flow direction
- F03B17/063—Other machines or engines using liquid flow with predominantly kinetic energy conversion, e.g. of swinging-flap type, "run-of-river", "ultra-low head" with rotation axis substantially at right angle to flow direction the flow engaging parts having no movement relative to the rotor during its rotation
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F03—MACHINES OR ENGINES FOR LIQUIDS; WIND, SPRING, OR WEIGHT MOTORS; PRODUCING MECHANICAL POWER OR A REACTIVE PROPULSIVE THRUST, NOT OTHERWISE PROVIDED FOR
- F03B—MACHINES OR ENGINES FOR LIQUIDS
- F03B13/00—Adaptations of machines or engines for special use; Combinations of machines or engines with driving or driven apparatus; Power stations or aggregates
- F03B13/12—Adaptations of machines or engines for special use; Combinations of machines or engines with driving or driven apparatus; Power stations or aggregates characterised by using wave or tide energy
- F03B13/26—Adaptations of machines or engines for special use; Combinations of machines or engines with driving or driven apparatus; Power stations or aggregates characterised by using wave or tide energy using tide energy
- F03B13/264—Adaptations of machines or engines for special use; Combinations of machines or engines with driving or driven apparatus; Power stations or aggregates characterised by using wave or tide energy using tide energy using the horizontal flow of water resulting from tide movement
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E10/00—Energy generation through renewable energy sources
- Y02E10/30—Energy from the sea, e.g. using wave energy or salinity gradient
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- Combustion & Propulsion (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Life Sciences & Earth Sciences (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Oceanography (AREA)
- Hydraulic Turbines (AREA)
- Other Liquid Machine Or Engine Such As Wave Power Use (AREA)
Abstract
A reaction turbine system for low-head hydro and tidal power is disclosed. The system consists of multiple Darrieus type turbine sections attached in series along a single horizontal rotating shaft. The Darrieus blades are long, rectangular, perpendicular to fluid flow and have an airfoil shaped cross-section. The blades in each Darrieus section are offset from the blades in the other sections. This greatly reduces the torque pulsation typical of a Darrieus turbine while keeping the simplicity of straight airfoil blades, the ability to generate power from multiple fluid flow directions and a high rotational speed. Such a system can be used in open bi-directional flowing water found in tidal areas or enclosed in one or more fluid flow ducts to efficiently generate low-cost power from a low-head hydro site.
Description
ECONOMIC LOW-HEAD HYDRO AND TIDAL POWER TURBINE
FIELD OF INVENTION:
This invention relates to reaction turbines for low-head hydro and tidal power applications.
BACKGROUND OF THE INVENTION:
Devices which take advantage of the energy in falling water have existed for several centuries. The earliest example is the water wheel. It is an impulse device which uses a multitude of buckets or paddles to catch falling or moving water, depositing it at a downstream point. The movement of the buckets or paddles spins a central supporting shaft which can do work or be used to generate power.
In the late 1800's and early 1900's hydro power innovators discovered the advantages of reaction turbines, which mainly generate power from pressure and energy differences in stream flow.
These turbines extract more power from streams than water wheels, rotate at higher speeds and accept much larger water flow volumes. Reaction turbines, such as the Francis or Kaplan, are therefore almost exclusively used at high flow hydroelectric sites. Both of these designs utilize a rotating disc of blades oriented in a plane perpendicular to the direction of exit flow. Impulse hydro power generating devices are still used in high-head (over 20m) low-flow applications (the Pelton design) and low-head (3m to lOm) low-flow applications (Cross-flow design).
The Francis, Kaplan, Pelton and Cross-flow hydro power designs are mature technologies and very well understood. None of these designs, however, is recommended for high-flow applications of less then 3 meters of head. The impulse designs cannot accept very large water flows while the Francis and Kaplan turbines are not practical. To utilize these large reaction turbines at low-head sites they must be partially elevated resulting in very low water pressures. Cavitation can result damaging the turbines and water transport surfaces. Variations on the Kaplan, such as the Starflow, inclined Kaplan and Bulb turbines, all of which are similar to water flowing through a propeller, have been recommended for low-head situations, however, they are not economical for heads of less than 3m and many rivers with higher heads and lesser flows.
One solution for economically generating power from ultra-low-head hydro sites (less than 3m of head) is adoption of the Darrieus turbine design. The Darrieus turbine was developed in France by Georges Darrieus in the 1920's to generate power from wind. It consists of a set of long, rectangular airfoils connected to a central rotating shaft. The airfoils may be curved to directly connect to the shaft or be straight and held parallel to the shaft by struts, arms or discs. Significant testing in the 1980's and 1990's demonstrated the utility of this turbine design. Darrieus turbines were, however, not widely adopted for wind power as pinwheel type wind turbines were more economical.
In the early 1980's a Canadian innovator, Barry V. Davis, applied the vertical-axis Darrieus design to water. Several different models were successfully tested in the laboratory and various waterways. Government funding ended in the late 1980's, however, several organizations are presently attempting to utilize the Davis turbine design in ultra-low-head hydro and tidal applications.
While the Davis turbine demonstrates the applicability of the Darrieus design in water, there are two key drawbacks. The first is rotation about the vertical axis. To extract the power from a wide ultra-low-head river many Davis turbines located side by side would be required. This increases the quantity of moving parts, gears and generators, resulting in increased complexity and cost. The second problem is torque pulsation. Unlike a propeller type turbine which receives fluid flow energy uniformly over time, Darrieus type turbines have spikes and troughs in energy imparted by the fluid. Torque on the rotating shaft peaks when a blade spins directly perpendicular to the direction of fluid flow and drops until the following blade approaches the point of peak torque.
Power generators cannot be easily connected to turbines with pulsating torque.
A solution to the torque pulsation problem is disclosed by Alexander M. Gorlov in U.S.
Patent 6,036,443 and Canadian Patent 2222115. The Gorlov turbine is similar to the Darrieus turbine, however the airfoil blades are curved into a helix at a constant diameter from the central rotating shaft, resulting in constant torque over time. While the Gorlov turbine is an innovative solution, it requires the construction helix type blades which are costly and complex relative to flat rectangular Darrieus airfoil blades. In addition, the complexity of helix blade construction makes the turbine much more susceptible to fabrication errors which can result in premature failure.
OBJECTS OF THE INVENTION:
It is an object of this invention to provide a simple, reliable and low-cost reaction turbine system for generating smooth non-pulsating power from ultra-low-head hydro or tidal flow sites.
SUMMARY OF THE INVENTION:
The present invention, which satisfies the foregoing objects, is a reaction turbine system consisting of several Darrieus type turbines connected in series along a single rotating shaft. In the invention's simplest form a long shaft is elevated at its ends by two supports. The supports permit rotation of the shaft and orient the longitudinal axis of the shaft horizontally and perpendicular to the direction of fluid flow. Three blade support discs are connected at their rotational centres to the shaft. The face of each disc is perpendicular to the longitudinal axis of the shaft. The leftmost Darrieus turbine module consists of four wing-like turbine blades extended between the leftmost and centre discs. Each blade is parallel to the shaft and has a constant tear-drop airfoil profile along its longitudinal axis. The four blades are all equidistant from the shaft and dispersed at 90 degree intervals around the shaft. A similar set of four blades extends between the centre and rightmost discs, making a second Darrieus turbine module. The only difference is that the blades are offset 45 degrees from the blades in the leftmost Darrieus turbine module. The quantity of Darrieus turbine modules and number of blades can be varied to meet the economics, energy conversion efficiency and shaft rotational speed requirements for a particular site.
The offsetting of blades between adjacent Darrieus turbine modules greatly reduces or eliminates the torque pulsation effect. While a simple horizontally oriented Darrieus turbine with four blades pulsates four times per rotation, a turbine system with two offset Darrieus turbine modules of four blades each pulsates eight times per rotation, smoothing out the pulsation effect and reducing the magnitude of each pulsation. Utilizing three sections would create 12 even smaller pulsations per rotation. With enough blades and / or modules the blades would cover the turbine system's circle of rotation, providing smooth torque and rotation. The complex and more expensive helical blades of the Gorlov turbine would not be required.
The invention is easily scalable and therefore more simple and economic than the Davis turbine. For example, to utilize the invention in a wide river the only adjustment is longer blade sections and / or a greater number of Darrieus turbine modules. As always, a single shaft, power generator and gearing system (if necessary) are required. In contrast, an equivalent Davis turbine system requires a multitude of vertical shafts, gears, generators and electrical systems, resulting in increased cost and complexity. Additional support structures are also necessary, increasing flow turbulence and decreasing energy conversion efficiency.
The invention is also more economic and practical than a horizontally oriented Darrieus turbine with a large number of blades. The Darrieus turbine has a higher number of blades per unit width than the invention and is therefore more costly. The greater blade density also reduces rotational speed, increasing the cost of gearing between the shaft and generator. This is a significant factor in megawatt installations. Besides the cost disadvantages, a Darrieus turbine with a large number of blades still experiences torque pulsation. To minimize the effect a very large blade density is required, but water flow through the turbine will become choked and overly turbulent.
Turbine efficiency is greatly reduced. A Darrieus turbine with 100% blade coverage is a cylinder, will not function and is not an option.
The invention can be placed in any area of unidirectional or bi-directional flow, such as a river, channel, duct or tidal zone. In low-head hydro applications best results are obtained by placing the Darrieus turbine modules in a fluid flow duct. The duct forces all the flow through the bladed area allowing the system to exceed the Betz limit of energy conversion efficiency (59.3%) for turbines in open fluid flow. Efficiencies approaching that of traditional reaction turbines are theoretically possible. The invention is also useful in tidal zones as the Darrieus turbine modules generate power from any flow perpendicular to the longitudinal axis of the shaft, such as tidal inflows and outflows. Power is generated by connecting a generator or gearing system and generator to either end of the shaft or any portion of the shaft not within any of the Darrieus turbine modules.
BRIEF DESCRIPTION OF THE DRAWINGS:
The invention can be better understood by reference to the accompanying drawings in which:
Figure 1 is a frontal view of the reaction turbine system down the direction of fluid flow, according to the present invention;
Figure 2 is a frontal view of a Darrieus turbine module down the direction of fluid flow, according to the present invention;
Figure 3 is a cross-sectional view of the Darrieus turbine module in Figure 2;
Figure 4 is a cross-sectional view of the two Darrieus turbine modules in series in Figure 1;
Figure 5 is a frontal view down the direction of flow of the reaction turbine system with an additional shaft support separating the Darrieus turbine modules, according to another embodiment of the present invention;
Figure 6 is a frontal view down the direction of flow of a Darrieus turbine module with a discontinuity in the shaft, according to another embodiment of the present invention;
Figure 7 is a cross-sectional view of the Darrieus turbine module in Figure 6;
Figure 8 is a frontal view of the reaction turbine system wherein the Darrieus turbine modules are enclosed by fluid flow duct, according to another embodiment of the present invention; and Figure 9 is cross-sectional view of the reaction turbine system in Figure 8 at the leftmost Darrieus turbine section.
DETAILED DESCRIPTION OF THE DRAWINGS:
Figure 1 is a frontal view down the direction of fluid flow for one embodiment of the invention. Shaft supports 1 elevate a shaft 2 and permit its rotation. The longitudinal axis of the shaft 2 is horizontal and perpendicular to the direction of fluid flow. In this embodiment two Darrieus turbine modules 9, further described in Figure 2, are connected to the shaft 2. Fluid flow through the reaction turbine system rotates the Darrieus turbine modules 9 which in turn rotate the shaft 2. A generator, gearing system and generator, or belt system and generator (none of which are shown) can be connected to either end of the rotating shaft to generate electric power.
Figure 2 is a frontal view down the direction of fluid flow of a Darrieus turbine module 9.
The Darrieus turbine module 9 consists of two blade support members 4 and a set of wing-like airfoil blades 3. A blade support member 4 can be a disc, radial spokes or any other blade support mechanism known in the art. Each blade 3 has a long rectangular profile between the two blade support members 4 and a constant teardrop airfoil cross-section along its longitudinal axis, as shown in Figure 3. A blade 3 can be constructed from a solid and non-flexible material such as metal, aluminum or reinforced polymer. The fluid flowing past each blade 3 creates lift and some drag, rotating the Darrieus turbine module 9. The shaft 2, which passes through the centre of each blade support member 4, is thereby rotated.
Figure 3, the cross-sectional view of Figure 2, helps explain rotation of a Darrieus turbine module 9. Each blade 3 is mounted parallel to the shaft 2 and equidistant from the shaft 2, resulting in a circle of rotation 6 about the shaft. The chord of each airfoil generally forms a chord on an arc of the circle of rotation 6. In this embodiment the blades 3 are spaced equally around the circle of rotation 6. This provides for the smoothest production of power. Any number of blades may be provided, depending on energy conversion efficiency and shaft 2 rotation speed requirements.
Adding blades 3 increases energy conversion efficiency but reduces shaft 2 rotational speed.
Conversely, eliminating blades 3 reduces energy conversion efficiency but increases shaft 2 rotational speed. Adding too many blades 3 can choke fluid flow, create excess turbulence and reduce energy conversion efficiency.
Fluid flow in the direction of arrows 5 causes the Darrieus turbine module 9 in Figure 3 to rotate clockwise. Fluid flow from the opposite direction will also cause clockwise rotation. In general, rotation of a Darrieus turbine module 9 will be from the tails of the airfoils 3 towards their noses. Maximum energy is imparted from the fluid flow when the chord of the leading blade 3 is perpendicular to the direction of flow 5. As one blade 3 leaves the maximum energy position and the next blade 3 moves towards it, energy imparted to the system decreases and increases. This creates the torque pulsation common to simple Darrieus turbines.
To eliminate or significantly reduce this pulsation effect the invention utilizes multiple Darrieus turbine modules 9 connected in series along a single shaft 2. The blades 3 in each Darrieus turbine module 9 are offset from the blades 3 in adjacent Darrieus turbine modules 9. This effectively multiplies the number of blades 3 which pass through the maximum energy zone during each rotation of the system. Figure 4, a cross-section of the Darrieus turbine modules 9 in Figure 1, demonstrates this effect. Where a single Darrieus turbine module 9 presents only four blades 3 per rotation, as in Figure 3, two Darrieus turbine modules 9 present eight blades 3 per rotation as in Figure 4. If required, additional blades 3 and / or Darrieus turbine sections 9 may be added to fully cover the circle of rotation 6 with blades. Such an arrangement would produce perfectly smooth rotation, torque and power. This is essential for connection to a power generator.
Figure 5 is an embodiment of the invention wherein a central shaft support 7 located between Darrieus turbine modules 9 helps elevate the shaft 2. Such a central shaft support 7 might be necessary when the span between shaft supports 1 is too wide for the shaft 2 to support its weight.
If more than two Darrieus turbine modules 3 are used, multiple central shaft supports 7 are an option.
A central shaft support 7 can also be used to connect the shaft 2 to a generator or gearing system and generator.
In a further embodiment of the invention, the central shaft 2 is discontinued within the span of one or more Darrieus turbine modules 9. Figure 6 is a frontal view down the direction of fluid flow of such a Darrieus turbine module 9. Figure 7 is the cross-sectional view of Figure 6 at the inside face of the rightmost blade support member 4. The Darrieus turbine module is exactly the same as in Figures 2 and 3 except that the shaft 2 is removed from the fluid flow area between blade support members 4. Less turbulence and higher energy conversion efficiency results. The Darrieus turbine module 9 imparts rotation to the shaft 2 by either being directly connected to the shaft 2 at one or both outside faces of its blade support members 4, or by being indirectly connected to the shaft 2 through other Darrieus turbine modules 9.
FIELD OF INVENTION:
This invention relates to reaction turbines for low-head hydro and tidal power applications.
BACKGROUND OF THE INVENTION:
Devices which take advantage of the energy in falling water have existed for several centuries. The earliest example is the water wheel. It is an impulse device which uses a multitude of buckets or paddles to catch falling or moving water, depositing it at a downstream point. The movement of the buckets or paddles spins a central supporting shaft which can do work or be used to generate power.
In the late 1800's and early 1900's hydro power innovators discovered the advantages of reaction turbines, which mainly generate power from pressure and energy differences in stream flow.
These turbines extract more power from streams than water wheels, rotate at higher speeds and accept much larger water flow volumes. Reaction turbines, such as the Francis or Kaplan, are therefore almost exclusively used at high flow hydroelectric sites. Both of these designs utilize a rotating disc of blades oriented in a plane perpendicular to the direction of exit flow. Impulse hydro power generating devices are still used in high-head (over 20m) low-flow applications (the Pelton design) and low-head (3m to lOm) low-flow applications (Cross-flow design).
The Francis, Kaplan, Pelton and Cross-flow hydro power designs are mature technologies and very well understood. None of these designs, however, is recommended for high-flow applications of less then 3 meters of head. The impulse designs cannot accept very large water flows while the Francis and Kaplan turbines are not practical. To utilize these large reaction turbines at low-head sites they must be partially elevated resulting in very low water pressures. Cavitation can result damaging the turbines and water transport surfaces. Variations on the Kaplan, such as the Starflow, inclined Kaplan and Bulb turbines, all of which are similar to water flowing through a propeller, have been recommended for low-head situations, however, they are not economical for heads of less than 3m and many rivers with higher heads and lesser flows.
One solution for economically generating power from ultra-low-head hydro sites (less than 3m of head) is adoption of the Darrieus turbine design. The Darrieus turbine was developed in France by Georges Darrieus in the 1920's to generate power from wind. It consists of a set of long, rectangular airfoils connected to a central rotating shaft. The airfoils may be curved to directly connect to the shaft or be straight and held parallel to the shaft by struts, arms or discs. Significant testing in the 1980's and 1990's demonstrated the utility of this turbine design. Darrieus turbines were, however, not widely adopted for wind power as pinwheel type wind turbines were more economical.
In the early 1980's a Canadian innovator, Barry V. Davis, applied the vertical-axis Darrieus design to water. Several different models were successfully tested in the laboratory and various waterways. Government funding ended in the late 1980's, however, several organizations are presently attempting to utilize the Davis turbine design in ultra-low-head hydro and tidal applications.
While the Davis turbine demonstrates the applicability of the Darrieus design in water, there are two key drawbacks. The first is rotation about the vertical axis. To extract the power from a wide ultra-low-head river many Davis turbines located side by side would be required. This increases the quantity of moving parts, gears and generators, resulting in increased complexity and cost. The second problem is torque pulsation. Unlike a propeller type turbine which receives fluid flow energy uniformly over time, Darrieus type turbines have spikes and troughs in energy imparted by the fluid. Torque on the rotating shaft peaks when a blade spins directly perpendicular to the direction of fluid flow and drops until the following blade approaches the point of peak torque.
Power generators cannot be easily connected to turbines with pulsating torque.
A solution to the torque pulsation problem is disclosed by Alexander M. Gorlov in U.S.
Patent 6,036,443 and Canadian Patent 2222115. The Gorlov turbine is similar to the Darrieus turbine, however the airfoil blades are curved into a helix at a constant diameter from the central rotating shaft, resulting in constant torque over time. While the Gorlov turbine is an innovative solution, it requires the construction helix type blades which are costly and complex relative to flat rectangular Darrieus airfoil blades. In addition, the complexity of helix blade construction makes the turbine much more susceptible to fabrication errors which can result in premature failure.
OBJECTS OF THE INVENTION:
It is an object of this invention to provide a simple, reliable and low-cost reaction turbine system for generating smooth non-pulsating power from ultra-low-head hydro or tidal flow sites.
SUMMARY OF THE INVENTION:
The present invention, which satisfies the foregoing objects, is a reaction turbine system consisting of several Darrieus type turbines connected in series along a single rotating shaft. In the invention's simplest form a long shaft is elevated at its ends by two supports. The supports permit rotation of the shaft and orient the longitudinal axis of the shaft horizontally and perpendicular to the direction of fluid flow. Three blade support discs are connected at their rotational centres to the shaft. The face of each disc is perpendicular to the longitudinal axis of the shaft. The leftmost Darrieus turbine module consists of four wing-like turbine blades extended between the leftmost and centre discs. Each blade is parallel to the shaft and has a constant tear-drop airfoil profile along its longitudinal axis. The four blades are all equidistant from the shaft and dispersed at 90 degree intervals around the shaft. A similar set of four blades extends between the centre and rightmost discs, making a second Darrieus turbine module. The only difference is that the blades are offset 45 degrees from the blades in the leftmost Darrieus turbine module. The quantity of Darrieus turbine modules and number of blades can be varied to meet the economics, energy conversion efficiency and shaft rotational speed requirements for a particular site.
The offsetting of blades between adjacent Darrieus turbine modules greatly reduces or eliminates the torque pulsation effect. While a simple horizontally oriented Darrieus turbine with four blades pulsates four times per rotation, a turbine system with two offset Darrieus turbine modules of four blades each pulsates eight times per rotation, smoothing out the pulsation effect and reducing the magnitude of each pulsation. Utilizing three sections would create 12 even smaller pulsations per rotation. With enough blades and / or modules the blades would cover the turbine system's circle of rotation, providing smooth torque and rotation. The complex and more expensive helical blades of the Gorlov turbine would not be required.
The invention is easily scalable and therefore more simple and economic than the Davis turbine. For example, to utilize the invention in a wide river the only adjustment is longer blade sections and / or a greater number of Darrieus turbine modules. As always, a single shaft, power generator and gearing system (if necessary) are required. In contrast, an equivalent Davis turbine system requires a multitude of vertical shafts, gears, generators and electrical systems, resulting in increased cost and complexity. Additional support structures are also necessary, increasing flow turbulence and decreasing energy conversion efficiency.
The invention is also more economic and practical than a horizontally oriented Darrieus turbine with a large number of blades. The Darrieus turbine has a higher number of blades per unit width than the invention and is therefore more costly. The greater blade density also reduces rotational speed, increasing the cost of gearing between the shaft and generator. This is a significant factor in megawatt installations. Besides the cost disadvantages, a Darrieus turbine with a large number of blades still experiences torque pulsation. To minimize the effect a very large blade density is required, but water flow through the turbine will become choked and overly turbulent.
Turbine efficiency is greatly reduced. A Darrieus turbine with 100% blade coverage is a cylinder, will not function and is not an option.
The invention can be placed in any area of unidirectional or bi-directional flow, such as a river, channel, duct or tidal zone. In low-head hydro applications best results are obtained by placing the Darrieus turbine modules in a fluid flow duct. The duct forces all the flow through the bladed area allowing the system to exceed the Betz limit of energy conversion efficiency (59.3%) for turbines in open fluid flow. Efficiencies approaching that of traditional reaction turbines are theoretically possible. The invention is also useful in tidal zones as the Darrieus turbine modules generate power from any flow perpendicular to the longitudinal axis of the shaft, such as tidal inflows and outflows. Power is generated by connecting a generator or gearing system and generator to either end of the shaft or any portion of the shaft not within any of the Darrieus turbine modules.
BRIEF DESCRIPTION OF THE DRAWINGS:
The invention can be better understood by reference to the accompanying drawings in which:
Figure 1 is a frontal view of the reaction turbine system down the direction of fluid flow, according to the present invention;
Figure 2 is a frontal view of a Darrieus turbine module down the direction of fluid flow, according to the present invention;
Figure 3 is a cross-sectional view of the Darrieus turbine module in Figure 2;
Figure 4 is a cross-sectional view of the two Darrieus turbine modules in series in Figure 1;
Figure 5 is a frontal view down the direction of flow of the reaction turbine system with an additional shaft support separating the Darrieus turbine modules, according to another embodiment of the present invention;
Figure 6 is a frontal view down the direction of flow of a Darrieus turbine module with a discontinuity in the shaft, according to another embodiment of the present invention;
Figure 7 is a cross-sectional view of the Darrieus turbine module in Figure 6;
Figure 8 is a frontal view of the reaction turbine system wherein the Darrieus turbine modules are enclosed by fluid flow duct, according to another embodiment of the present invention; and Figure 9 is cross-sectional view of the reaction turbine system in Figure 8 at the leftmost Darrieus turbine section.
DETAILED DESCRIPTION OF THE DRAWINGS:
Figure 1 is a frontal view down the direction of fluid flow for one embodiment of the invention. Shaft supports 1 elevate a shaft 2 and permit its rotation. The longitudinal axis of the shaft 2 is horizontal and perpendicular to the direction of fluid flow. In this embodiment two Darrieus turbine modules 9, further described in Figure 2, are connected to the shaft 2. Fluid flow through the reaction turbine system rotates the Darrieus turbine modules 9 which in turn rotate the shaft 2. A generator, gearing system and generator, or belt system and generator (none of which are shown) can be connected to either end of the rotating shaft to generate electric power.
Figure 2 is a frontal view down the direction of fluid flow of a Darrieus turbine module 9.
The Darrieus turbine module 9 consists of two blade support members 4 and a set of wing-like airfoil blades 3. A blade support member 4 can be a disc, radial spokes or any other blade support mechanism known in the art. Each blade 3 has a long rectangular profile between the two blade support members 4 and a constant teardrop airfoil cross-section along its longitudinal axis, as shown in Figure 3. A blade 3 can be constructed from a solid and non-flexible material such as metal, aluminum or reinforced polymer. The fluid flowing past each blade 3 creates lift and some drag, rotating the Darrieus turbine module 9. The shaft 2, which passes through the centre of each blade support member 4, is thereby rotated.
Figure 3, the cross-sectional view of Figure 2, helps explain rotation of a Darrieus turbine module 9. Each blade 3 is mounted parallel to the shaft 2 and equidistant from the shaft 2, resulting in a circle of rotation 6 about the shaft. The chord of each airfoil generally forms a chord on an arc of the circle of rotation 6. In this embodiment the blades 3 are spaced equally around the circle of rotation 6. This provides for the smoothest production of power. Any number of blades may be provided, depending on energy conversion efficiency and shaft 2 rotation speed requirements.
Adding blades 3 increases energy conversion efficiency but reduces shaft 2 rotational speed.
Conversely, eliminating blades 3 reduces energy conversion efficiency but increases shaft 2 rotational speed. Adding too many blades 3 can choke fluid flow, create excess turbulence and reduce energy conversion efficiency.
Fluid flow in the direction of arrows 5 causes the Darrieus turbine module 9 in Figure 3 to rotate clockwise. Fluid flow from the opposite direction will also cause clockwise rotation. In general, rotation of a Darrieus turbine module 9 will be from the tails of the airfoils 3 towards their noses. Maximum energy is imparted from the fluid flow when the chord of the leading blade 3 is perpendicular to the direction of flow 5. As one blade 3 leaves the maximum energy position and the next blade 3 moves towards it, energy imparted to the system decreases and increases. This creates the torque pulsation common to simple Darrieus turbines.
To eliminate or significantly reduce this pulsation effect the invention utilizes multiple Darrieus turbine modules 9 connected in series along a single shaft 2. The blades 3 in each Darrieus turbine module 9 are offset from the blades 3 in adjacent Darrieus turbine modules 9. This effectively multiplies the number of blades 3 which pass through the maximum energy zone during each rotation of the system. Figure 4, a cross-section of the Darrieus turbine modules 9 in Figure 1, demonstrates this effect. Where a single Darrieus turbine module 9 presents only four blades 3 per rotation, as in Figure 3, two Darrieus turbine modules 9 present eight blades 3 per rotation as in Figure 4. If required, additional blades 3 and / or Darrieus turbine sections 9 may be added to fully cover the circle of rotation 6 with blades. Such an arrangement would produce perfectly smooth rotation, torque and power. This is essential for connection to a power generator.
Figure 5 is an embodiment of the invention wherein a central shaft support 7 located between Darrieus turbine modules 9 helps elevate the shaft 2. Such a central shaft support 7 might be necessary when the span between shaft supports 1 is too wide for the shaft 2 to support its weight.
If more than two Darrieus turbine modules 3 are used, multiple central shaft supports 7 are an option.
A central shaft support 7 can also be used to connect the shaft 2 to a generator or gearing system and generator.
In a further embodiment of the invention, the central shaft 2 is discontinued within the span of one or more Darrieus turbine modules 9. Figure 6 is a frontal view down the direction of fluid flow of such a Darrieus turbine module 9. Figure 7 is the cross-sectional view of Figure 6 at the inside face of the rightmost blade support member 4. The Darrieus turbine module is exactly the same as in Figures 2 and 3 except that the shaft 2 is removed from the fluid flow area between blade support members 4. Less turbulence and higher energy conversion efficiency results. The Darrieus turbine module 9 imparts rotation to the shaft 2 by either being directly connected to the shaft 2 at one or both outside faces of its blade support members 4, or by being indirectly connected to the shaft 2 through other Darrieus turbine modules 9.
In an open fluid flow area some flow will pass around the reaction turbine system, imparting no energy. Figure 8 is a frontal view down the direction of flow of an embodiment of the invention wherein a duct 8 minimizes this loss of flow. Figure 9 is a cross-section of Figure 8 at the leftmost Darrieus turbine module 9. In this embodiment the Darrieus turbine modules 9 are surrounded by a duct 8 which forces almost all the flow through the blades 3. The smaller the minimum gap between duct 8 walls and the blades 3, the higher the energy conversion efficiency. If Darrieus turbine modules 9 are not adjacent to each other, a separate duct 8 for each non-adjacent Darrieus turbine module 9 is an option.
Claims (11)
1. A reaction turbine system for harnessing energy from fluid flow comprising a shaft, at least two shaft supports which elevate the shaft, permit rotation of the shaft and orient the longitudinal axis of the shaft horizontally and perpendicular to the direction of fluid flow, and a plurality of Darrieus turbine modules arranged in series along the shaft, each Darrieus turbine module comprising:
at least one blade support member fixedly mounted to the shaft for rotation in a plane perpendicular to the longitudinal axis of the shaft; and a plurality of turbine blades mounted to the blade support member(s) in the Darrieus turbine module, each turbine blade being wing shaped, having a constant tear-dropped airfoil cross-section along its longitudinal axis, having its longitudinal-axis parallel to the longitudinal axis of the shaft, mounted equidistant from the shaft as all other turbine blades in the reaction turbine system, having its airfoil cross-section oriented in the same direction around the circle of rotation as all the other turbine blades in the reaction turbine system, and having a longitudinal axis that does not coincide with the longitudinal axis of any blade in any adjacent Darrieus turbine module.
at least one blade support member fixedly mounted to the shaft for rotation in a plane perpendicular to the longitudinal axis of the shaft; and a plurality of turbine blades mounted to the blade support member(s) in the Darrieus turbine module, each turbine blade being wing shaped, having a constant tear-dropped airfoil cross-section along its longitudinal axis, having its longitudinal-axis parallel to the longitudinal axis of the shaft, mounted equidistant from the shaft as all other turbine blades in the reaction turbine system, having its airfoil cross-section oriented in the same direction around the circle of rotation as all the other turbine blades in the reaction turbine system, and having a longitudinal axis that does not coincide with the longitudinal axis of any blade in any adjacent Darrieus turbine module.
2. The reaction turbine system of claim 1, wherein at least one blade support member is a circular disc;
3. The reaction turbine system of claim 1, wherein at least one blade support member is a plurality of radial spokes;
4. The reaction turbine system of claim 1, wherein at least one shaft support is located between adjacent Darrieus turbine modules;
5. The reaction turbine system of claim 1, wherein at least one blade support member supports the blades of adjacent Darrieus turbine modules;
6. The reaction turbine system of claim 1, wherein at least one Darrieus turbine module has a discontinuity in the shaft and the blade support members are connected only by turbine blades;
7. The reaction turbine system of claim 1, wherein at least one Darrieus turbine module is enclosed by a fluid flow channel;
8. The reaction turbine system of claim 1, wherein at least one Darrieus turbine module is enclosed by a fluid flow duct;
9. The reaction turbine system of claim 1, wherein the shaft is connected to a power generator;
10. The reaction turbine system of claim 1, wherein the shaft is connected to a gearing system connected to a power generator; and
11. The reaction turbine system of claim 1, wherein at least one Darrieus turbine module has its blades mounted at equal intervals around the blades' circle of rotation.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA002532734A CA2532734A1 (en) | 2006-01-11 | 2006-01-11 | Economic low-head hydro and tidal power turbine |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA002532734A CA2532734A1 (en) | 2006-01-11 | 2006-01-11 | Economic low-head hydro and tidal power turbine |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2532734A1 true CA2532734A1 (en) | 2007-07-11 |
Family
ID=38236286
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002532734A Abandoned CA2532734A1 (en) | 2006-01-11 | 2006-01-11 | Economic low-head hydro and tidal power turbine |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2532734A1 (en) |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| BE1017920A3 (en) * | 2008-01-02 | 2009-11-03 | Rutten S A | Hydroelectric machine e.g. hydraulienne floating hydro-generator, for generating electric power, has rotor provided with horizontal axle that is cooperated with bearings integrated with floating structure to be moored in operation |
| GB2462880A (en) * | 2008-08-28 | 2010-03-03 | Roderick Allister Mcdonald Gal | Horizontal axis cross flow turbine |
| US8002523B2 (en) | 2007-10-26 | 2011-08-23 | Borden Saxon D | Turbine system and method for extracting energy from waves, wind, and other fluid flows |
| BG66163B1 (en) * | 2007-11-05 | 2011-09-30 | Виктор СПАСОВ | Multi-turbine hydropower system |
| WO2015186086A1 (en) * | 2014-06-04 | 2015-12-10 | Cos.B.I. Costruzione Bobine Italia S.R.L. | Hydroelectric turbine with horizontal axis |
-
2006
- 2006-01-11 CA CA002532734A patent/CA2532734A1/en not_active Abandoned
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US8002523B2 (en) | 2007-10-26 | 2011-08-23 | Borden Saxon D | Turbine system and method for extracting energy from waves, wind, and other fluid flows |
| BG66163B1 (en) * | 2007-11-05 | 2011-09-30 | Виктор СПАСОВ | Multi-turbine hydropower system |
| BE1017920A3 (en) * | 2008-01-02 | 2009-11-03 | Rutten S A | Hydroelectric machine e.g. hydraulienne floating hydro-generator, for generating electric power, has rotor provided with horizontal axle that is cooperated with bearings integrated with floating structure to be moored in operation |
| GB2462880A (en) * | 2008-08-28 | 2010-03-03 | Roderick Allister Mcdonald Gal | Horizontal axis cross flow turbine |
| WO2010023437A2 (en) * | 2008-08-28 | 2010-03-04 | Roderick Allister Mcdonald Galbraith | Improvements in and relating to turbines |
| WO2010023437A3 (en) * | 2008-08-28 | 2011-01-13 | Roderick Allister Mcdonald Galbraith | Improvements in and relating to turbines |
| WO2015186086A1 (en) * | 2014-06-04 | 2015-12-10 | Cos.B.I. Costruzione Bobine Italia S.R.L. | Hydroelectric turbine with horizontal axis |
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