WO2017134325A1

WO2017134325A1 - Wind flow concentrator

Info

Publication number: WO2017134325A1
Application number: PCT/ES2017/070060
Authority: WO
Inventors: Francisco Javier Ferrandez Pastor; Juan Manuel GARCÍA CHAMIZO; Sergio GÓMEZ TRILLO
Original assignee: Universidad De Alicante
Priority date: 2016-02-04
Filing date: 2017-02-03
Publication date: 2017-08-10
Also published as: ES2595481A1; ES2595481B1

Abstract

The invention relates to a wind flow concentrator (202) that has vanes (215) in the manner of a guide ring circumscribed about a rotor (212, 213) of a wind turbine (201) having a vertical shaft (210).

Description

WIND FLOW CONCENTRATOR Object of the invention

The present invention relates to the use of circulating wind breezes on the earth's surface for the generation of electricity for domestic and industrial use.

It is the object of the present invention to formalize the method for the characterization of a wind flow concentrator incorporated on a vertical axis wind turbine. Its purpose is to supply the low energy density of the circulating breezes on the earth's surface through its capture and concentration, achieving a significant increase in speed before being injected efficiently on the turbine's sweeping surface. The wind flow concentrator is configured to optimize the use of currents regardless of their direction.

The contexts of application of the invention are numerous, such as isolated dwellings, agricultural buildings, industrial facilities, service constructions, auxiliaries, technical control, maintenance, etc. thus any architectural volume located in a similar environment and that requires electricity for its correct operation.

Prior art

In recent years, systems that use renewable resources as a source have positioned themselves as an interesting alternative for energy production.

Among the available sources, wind energy has been configured as one of the fastest growing renewable energy sources in recent years.

The wind concentration system has great potential thanks to the improvement that occurs in the performance of the turbine on which it is incorporated. This potential is based on the cubic function that governs the wind speed in relation to when determining the available wind power.

^1one

P = P ^Sv ( ^a )

Being, P: Available wind power

p: Density

S: Turbine pickup surface

v: Wind breeze speed

Energy microgeneration systems provide energy accessibility to regions lacking this basic service, while in territories with consolidated electricity networks, these types of systems are useful when it comes to self-supplying buildings of all kinds. The incorporation of the wind concentration system increases the potential performance and operating time compared to the free exercise of small wind turbines. This result expands the scope of geographic implementation of these energy production systems.

The closest state of the art is made up of designs of concentrators for vertical axis wind turbines with several sections of circulation described in US 1595578 A and WO / 2013/038215.

US 1595578 refers to an annular housing wind concentrating device having radial ducts with side, upper and lower walls converging towards the central axis of the housing. In the center of the housing is the rotor provided with blades.

WO / 2013/038215 refers to a double turbine wind power plant arranged on a vertical axis, which has a machine housing built on a solid base, a roof structure suitable for its height, an internal rotor and a rotor external composed of a series of blades. The wind power plant is characterized in that the external rotor, which rotates in a direction opposite to that of the internal rotor, is arranged in a vertical axis that shares with the internal rotor. The ends of the lower shaft of the two rotors are connected to first and second electric machines producing electricity, either directly, or with the help of first and second transmission devices.

Description of the invention

The characterization method of the invention allows a wind flow concentrator to be realized from certain characteristics of the vertical axis wind turbine, the structural conditions and the energy requirements of the architectural volume on which the implementation is carried out.

The result of the method is the generation of the geometry of the wind flow concentrator and the blades that make up said concentrator. The advantages of the method translate into optimizing the design and manufacturing process of the concentrator, by reducing the manufacturing time of prototypes, models and tests with different models until reaching the satisfactory concentrator structure. As can be seen, the application of the method has an immediate industrial application.

The result is a wind flow concentrator characterized by an architecture capable of sectorizing the entry of wind in different sections by injecting the wind flow strategically. The incorporation of the wind flow concentrator on the rotor increases the wind uptake surface (S), facilitating its entry through the different openings and carrying out its concentration as it progresses through the circulation sections. The result of the sectorized injection is the development of a vortex interior circulation that permanently affects the characteristic lift range of the aerodynamic profile that defines the geometry of the rotation blade. This causes the nominal operation of the turbine to be achieved with low speed breezes.

In the presence of speeds of relative importance, the wind flow concentrator adapts its architecture in order to regulate the flow input, delaying the activation of the wind turbine's own regulatory devices. In the presence of significant winds, the wind flow concentrator has the necessary mechanisms to proceed to the closing of the openings proceeding to stop the rotor.

Throughout the description and claims the word "comprises" and its variants are not intended to exclude other technical characteristics, components or steps.

The following examples and drawings are provided by way of illustration, and are not intended to be limiting of the present invention. In addition, the present invention covers all possible combinations of particular and preferred embodiments indicated herein. Brief description of the figures

Figure 1A: shows an aerodynamic profile with null lift, where the angle of attack has a null value (β ₀ ).

Figure 1 B: shows an aerodynamic profile with maximum lift, where the angle of attack has maximum value ^ _max ).

Figure 1C: shows an aerodynamic profile where the boundary layer has been detached and the lift force generated when the value of the angle of attack exceeds the maximum lift value ^ _max ).

Figures 2A, 2B, 2C: show different longitudinal sections of type sections where you can see three values of the parameter ε that defines the angular range of the type section from the distance between injection and collection sections.

Figure 3: Descriptive flowchart of the wind flow concentrator characterization method.

Figure 4A: Plan section of the interior architecture of the wind flow concentrator with a vertical axis wind turbine along line A-A 'of Figure 5.

Figure 4B: Figure 4A depicting the direction of the surrounding wind breezes and the channeling of said breezes through the concentrator.

Figure 5: Elevation of the wind flow concentrator. Detailed description of the invention

The method of calculating a wind-flow concentrator (202) for vertical axis wind turbine (201) is detailed in Figure 1. The structure of the wind flow concentrator (202) is given by the resolution of a plurality of fundamental objectives, providing the assembly (201, 202) comprising a concentrator (202) and a wind turbine (201), with particular benefits in relation to to its architecture and operability. These objectives are as follows:

- Operation before any wind direction adopted (1);

- Increase in efficiency (2) of the vertical axis wind turbine (201);

- Minimize the development of turbulent effects (3) around the whole (201, 202);

- Resolution capacity in the presence of strong winds (4);

- Structural stability (5);

- Compatibility before installations of the architectural volume where the set (201, 202) can be installed (6);

- Global performance control (7) of the set (201, 202). The following features are responsible for responding to such objects, modeling the architecture of the hub (202) from the resolution of different specific actions included in the flowchart illustrated in the figure "!:

Independent structural design against the wind direction (101): The turbulent nature of the breezes on the earth's surface derives in the absence of a predominant sense. Given the purpose of its capture and energy use, a geometry of the concentrator (202) is provided that gives identical relevance to any direction adopted by the current. This criterion is translated into a circumscribed perimeter structure (102) on the wind turbine (201), achieving a valid design against any wind course adopted.

- Acceleration of wind circulation (103): The interior architecture modeling is based on the continuity equation for ideal fluids. The expression relates the speed of a given flow to the passage section in its circulation through a section of impermeable walls. In the case that the entrance section has a greater surface compared to the exit section, the section converges, gradually reducing the passage section, which results in an increase in its speed, in a subsonic regime. Taking this equation into account, a structure composed of a certain number of convergent sections (104) is modeled, in which the wind current progressively increases its speed until its injection into the wind turbine (201).

Efficient injection (105) on the blades of the wind turbine (201): The incorporation of the concentrator (202) on the wind turbine (201) produces two differentiated behaviors in relation to the flow course: the first is determined by the complete passage of the flow through of the concentrator (202), while the second covers from the injection of the flow to its incidence in the wind turbine rotation blades (201). o In the first case, an efficient design is considered to be one that minimizes the formation of the boundary layer, facilitating as uniform an advance as possible towards the wind turbine (201).

o In the second case, an efficient design is considered to be the one that injects the flow into the range of the most characteristic lift of the blade, minimizing the formation of possible turbulent effects and boundary layer detachments. Taking these considerations into account, a homogeneous interior architecture consisting of a certain number of convergent sections responsible for the capture of wind flow, concentration and multiple injection is sought within the terms of the lift range. The geometry of these sections is identical in order to materialize a homogeneous architecture and independent of the course of the breezes.

The method includes the following steps for internal modeling: o Determination of the maximum lift range (106): The determination and subsequent reproduction of this range along the rotation allows convergent type sections that inject specifically accelerated wind flow to be modeled. in that region. The angle of attack (β) measures the incidence of wind flow in relation to the aerodynamic profile rope. This maximum lift range comprises from the point corresponding to a null value (β ₀ ), illustrated in Figure 1A, to the point at which the maximum lift occurs ^ _max ) illustrated in Figure 1 B. This last value is associated to the previous instant of the detachment of the boundary layer and the consequent decrease of the generated force, illustrated in Figure 1 C. o Calculation (107) of the wind flow injection section (S¡):

Initially a wind direction is defined for the dimensioning of the type section, object of modeling and subsequent reproduction in the architecture of the concentrator (202). Parameter N _Y defines the number of sections in which the concentrator is divided. The angle γ determines the resulting unit range by the following expression,

This portion comprises enough space for the wind flow injection to be complete in the defined lift range. That is, the angle γ covers the space defined from the aerodynamic profile in position β ₀ until reaching the _max position, including the space necessary to make the injection effective in the entire range included. This action is achieved by iterating the value of the profile string, where the profile is the aerodynamic section (213). The injection section of the type section is given by the straight section to the defined portion and limited by the maximum angle of attack in relation to the aerodynamic profile in position β ™

Calculation (108) of the collection section (S _c ) of the type segment: The collection section is solved by applying the continuity equation, so that the parameters are defined as follows:

Being,

v _t : Average speed of wind breezes

p _t : Air density

S _c : Collection area

v _n : Wind speed in nominal operation of the turbine

p ₂ : Air density

5 _¿ : Injection surface

Modeling (109) of type sections with different section gradients according to their wind flow uptake: The parameter ε defines the angular range of the type section from the distance between sections of injection (S¡) and uptake (S _c ). With the purpose of knowing the most effective geometry, different section gradients are projected according to said parameter ε for later analysis.

Modeling (1 10) of the side walls for each type section: With the help of a rectangular mesh the work space is discretized to define the possible solutions. The different solutions are made up of a concatenation of segments originating at one of the ends of the collection section (S _c ), either point "x" or "y", ending at point "χ '" or " and "'respectively, belonging to the injection section (S¡). In order to have an estimate of the boundary layer to be developed for each possible solution, the calculation of the displacement thickness (5 ^* ) derived from the Falkner-Skan expression is performed, using the following expression:

Being,

x: Material surface length

a: Tilt angle of the surface with respect to the horizontal Re _x : Reynolds number

Being,

y: coordinate

eu ( _X sliding speed

v: Kinematic viscosity

the differential equation of Falkner-Skan,

Being,

/ (O) = Γ (0) = 0, '(∞) =! The expression of Falkner-Skan originates from the Blasius equation that allows to know the development of the boundary layer generated on flat material surfaces. In the case of the expression of Falkner-Skan, it is possible to specify this phenomenon on surfaces with a certain degree of inclination with respect to the direction of the predominant breezes.

The application of the Dijkstra algorithm on the possible solutions defines the concatenation that generates the lowest overall thickness, and on which its curved function can be defined. The result is four possibilities depending on the curvature of its curves.

Analysis (11 1) of the behavior of circulating flow through different type sections: By means of a numerical simulation computer tool, the evaluation of the sections previously modeled (109) and their corresponding curves (1 10) is carried out, solving that configuration that offers better performance in relation to the injection speed achieved and the possibility of assembly with the adjacent face.

First, in the modeling stage (109) of type sections with different section gradients, different type sections are modeled according to ε, complying that all type sections have the same catchment surface (S _c ) and the same injection surface (S¡). Later in the modeling stage (110) of the side walls (χ-χ ', y-y'), the modeling of the lateral faces that proceed to the closure of the type section is carried out, identifying which curves are the most suitable according to their concavity or convexity Hence, the four possible solutions in particular for each section modeled in the modeling stage (109) of type sections with different section gradients: two convex curves, a convex curve-a concave curve, a concave curve-a convex curve, Two concave curves. In step (11 1) we proceed to evaluate which configuration offers better performance.

Once the calculation of the type section has been carried out, it is extrapolated along the circumference of the wind turbine (201), completing the homogeneous structure as can be seen in Figure 4A. The blades (215) are the result of "joining" a side face (χ-χ ', y-y') of a section, with the side face (y-y ', x-x') adjacent or opposite the section adjacent. That is, the sections have two side walls (χ-χ ', y-y'). o Assembly (1 12) of the resulting blade (215): The blade resulting from the assembly of two immediately opposite or adjacent faces participating in two adjacent sections of wind circulation is defined as a blade (215). As noted, the blade assembly is carried out with a wall (χ-χ ', y-y') of a section and with the side face (y-y ', x-x') adjacent or opposite of the adjacent section . The blade (215) is executed respecting the established tolerances in terms of the minimum thickness of the piece, and the space between the rotation of the rotor (212, 213) of the wind turbine (201) and the surface of said blades (215) . The union of the outer end of the blade (215) is carried out by means of a curved turning to favor the wind flow entrance independently of the direction, while the union of the inner end has been modeled with an aerodynamic geometry favoring the encounter between the injected flow through the concentrator (202) and the one that circulates internally. Modeling (1 13) of the architecture of the concentrator (202) that crosses the wind flow through the reproduction of the type section: Defined the blade (215) characteristic of the concentrator (202), it proceeds to its perimeter reproduction to complete the architecture of greater efficiency in relation to the number of traffic sections. o Numerical simulation (1 14) of the modeled prototype: Through numerical simulation (1 14), the evaluation of the base prototype is carried out to carry out its analysis in relation to the benefits achieved, as well as the identification of possible specific improvements to be made in your design

Optimum operability (115): The incorporation of the concentrator (202) achieves a nominal operation of the wind turbine (201) with lower speed breezes than those required by a wind turbine without a concentrator (202). This causes a rapid activation of the power regulation mechanisms and, if necessary, the wind turbine stop mechanism (201). The performance of the structure is related to the rotation frequency of the wind turbine (201). By presetting (1 17) a series of control milestones and monitoring (118) both the speed of the circulating breezes, and the wind turbine behavior (201), the activation of the wind turbine mechanisms (201) can be anticipated ), regulating (1 19-120) the entry of wind flow to the concentrator (202), thus decreasing the internal circulation speed. The stop (123) of the wind turbine (201) will happen in cases of high winds, where even if the mechanisms to regulate (121, 122, 124, 125) the wind speed of the wind turbine (201) are activated, the speed cannot be reduced of rotation of the wind turbine (201). The last three objectives, structural stability (5), compatibility with installations of the architectural volume (6) and overall control of the system performance (7), are directly related to the integration in the architectural volume. The benefits that respond to such precepts are the following

Configuration (126) material based on lightweight materials with high structural resistance and outdoor exposure.

Spaces (128) enabled for technical use.

Devices for monitoring (130) the behavior of the assembly (201, 202).

The possibility of integration between these elements is related to eliminating possible interference and inconvenience caused by the mechanical action on the consolidated architectural structure and the activities carried out inside. To resolve such benefits, the concentrator (202) comprises an upper disk

(301) and a lower disk (216), the blades (215), the upper disk and the lower disk (216) forming the wind flow passage sections.

The lower disk (216) is the element of the concentrator (202) between the wind turbine (201) and the building volume. The modeling (127) of the lower disk (216) has in It has to meet the basic levels in terms of the level of noise originated, transmission of efforts to the structure and compatibility with other types of service facilities. For this, a lower disk (216) has been modeled, which can comprise a double sandwich panel, with an insulating core based on rock wool or similar, and an aluminum, fiberglass or similar finish sheet, and an inner chamber. The inclusion of an air chamber causes an elastic mass-spring-mass device that attenuates the transmission of noise to the adjacent rooms, improving said performance with the inclusion of an acoustic insulator type rock wool or similar. The main function to take into account in the modeling (129) of the upper disk (301), is to serve as a surface for the support of the components of the regulator and closing device of the concentrator (202). The structure of the upper disk (301) is similar to that of the lower disk (216), based on a double sandwich panel with intermediate chamber, with the purpose of inserting inside it the necessary devices and mechanisms for the correct functioning of the concentrator (202 ). The inclusion of a surface as a cover of the concentrator (202) generates a useful space that can be used for installation of solar systems or collection and use of rainwater, for example, for domestic use. The devices for monitoring (130) the behavior of the assembly (201, 202) are configured to measure an operating parameter of the assembly (201, 202) selected from: structural stability parameters (131); habitability parameters (132); generated noise parameters (133); potential performance parameters (134); and combinations thereof.

These devices measure the operating parameters of the assembly (201, 202); if they are within the acceptable ranges, the calculated concentrator (202) is valid, if not, the calculation process is started again. In the embodiment illustrated in the figures, the architecture of the concentrator (202) has an impeller-like geometry or circumscribed crown crown on the vertical axis wind turbine (201) (210). The concentrator (202) comprises a plurality of blades (215), which can be perpendicular to a lower disk (216) and an upper disk (301). Figure 4A shows a section in plan of a wind microgeneration system for use electricity generation domestic, illustrating: a) a wind turbine (201) responsible for the transformation of wind kinetic energy into electrical energy;

b) a concentrator (202) responsible for the concentration, direction and injection of wind flow over the wind turbine (201).

The wind turbine (201) comprises its own regulation devices (214) of the generated power, a vertical axis (210) supported on a base platform (211), a clamping structure (212) and rotation blades defined by an aerodynamic section (213).

Figures 4A and 4B show an embodiment where the concentrator (202) comprises 13 blades (215), responsible for the concentration and injection of the wind flow to the rotor (212, 213) of the wind turbine (201), regardless of the direction of the circulating breezes

Some of the advantages of the concentrator (202) of the invention can be summarized in:

- Increase of the electric power generated. The incorporation of the concentrator (202) facilitates reaching the nominal power of the wind turbine (201) at lower speeds, resulting in a longer time in nominal operation.

- Increase operating range of performance. The flow regulating devices facilitate that the architecture of the concentrator (202) can be adapted to the current velocity requirements.

- Adaptation to the turbulent nature of the breezes: The design of the blades (215) and the sectorization practiced allows continuous collection and injection in the presence of breezes of a turbulent nature without affecting performance. Compatibility of use with other microgeneration systems and technical equipment: The configuration of the concentrator (202) allows the incorporation of other microgeneration systems such as solar utilization systems, as well as passive solutions, technical equipment, landscaped roofs, etc. Ease of installation: Its incorporation is feasible for the majority of architectural volumes classified as rural, as well as the vast majority of industrial, technical, service, auxiliary, agricultural, military, etc. installations. and any other volume located in environments similar that requires electrical energy for optimum operation.

Its dimensions are adaptable for integration into any type of structure, being also scalable vertically, adding new modules.

Taking into account what has been described, a first aspect of the invention relates to a wind flow concentrator (202) comprising:

1 a) a plurality of blades (215) configured as a circumscribed guidewire on a rotor (212, 213) of a vertical axis wind turbine (201) (210).

According to other characteristics of the concentrator (202) of the invention:

The blades (215) can be:

2. configured to define converging traffic sections towards the rotor (212, 213);

3. configured to concentrate and inject wind flow into the rotor (212, 213), regardless of circulating breeze directions as they are distributed angularly on a regular basis.

The concentrator (202) may comprise:

4. thirteen blades (215);

5. a closing element (216, 301) selected from a lower disk (216), an upper disk (301) and combinations thereof, where the vanes (215) and the closing element (216, 301) form a plurality of circulation sections to concentrate and inject wind flow into the wind turbine;

6. a lower disk (216) configured as a base for a vertical arrangement of the blades (215);

7. a lower disk (216) comprising a plurality of sound insulation panels (216A).

Claims

1. Wind flow concentrator (202) characterized in that it comprises:

1a) a plurality of blades (215) configured as a circumscribed guidewire on a rotor (212, 213) of a vertical axis wind turbine (201)

(210).

2. Wind flow concentrator (202) according to claim 1 characterized in that the vanes (215) are configured to define convergent circulation sections towards the rotor (212, 213).

3. Wind flow concentrator (202) according to claim 1 characterized in that the vanes (215) are configured to concentrate and inject the wind flow into the rotor (212, 213), regardless of circulating breeze directions as they are angularly distributed from regular form

4. Wind flow concentrator (202) according to claim 1 characterized in that it comprises thirteen blades (215).

5. Wind flow concentrator (202) according to claim 1 characterized in that it comprises a closing element (216, 301) selected from a lower disk (216), an upper disk (301) or both, where the blades (215) and the closing element (216, 301) form a plurality of circulation sections to concentrate and inject wind flow into the wind turbine.

6. Wind flow concentrator (202) according to claim 1 characterized in that it comprises a lower disk (216) configured as a base for a vertical arrangement of the blades (215).

7. Wind flow concentrator (202) according to claim 1 characterized in that it comprises a lower disk (216) comprising a plurality of sound insulation panels (216A).