ITRM20120529A1 - WIND OR HYDRAULIC TURBINE WITH PERPENDICULAR AXIS WITH THE CURRENT EQUIPPED WITH INDIVIDUALLY ADAPTIVE MOBILE BLADES. - Google Patents

Description

DESCRIPTION of the industrial invention entitled:

"WIND OR HYDRAULIC TURBINE WITH AXIS PERPENDICULAR TO THE CURRENT EQUIPPED WITH INDIVIDUALLY ADAPTABLE MOVING BLADES"

DESCRIPTION

The present invention refers to a system for converting energy from a renewable source, and in particular the energy of a wind flow, into electrical energy. For the exploitation of the so-called renewable energy sources, wind and hydraulic turbines of various types are known.

In the technical-scientific literature (1,2) new methods and systems have been described for improving the efficiency of the turbine with vertical axis. In article (1) a turbine with individual control of moving blades has been described. The disadvantage of this system is that the servomechanisms are installed on the hub, near the rotation axis of the turbine and each servomechanism transfers the control movement to the blade via a long bar. This configuration significantly limits the angles and speeds of operation. In article (1) the position of the blade rotation axis has not been indicated, which is very important for the functioning of the system; furthermore, the dynamic load on the blade and the characteristics necessary for the servomechanism to guarantee the functioning of the system have not been analyzed.

In the patent (2) a turbine with a vertical axis has been described, which has an individual control system for the angles of incidence of each blade and for the angles of each flap. This patent, however, provides a detailed description only for the electrical generator and the electrical matrix converter. In the patent (2) the positioning of the servomechanisms has been indicated incorrectly. According to drawing (2) the position of the axis of the servo mechanism for controlling the angle of attack of the blade is positioned on the leading edge of the blade profile. With this configuration, the torque of the servomechanism will probably not be achievable. In the patent (2) the method and the control system do not include an important parameter: the angular speed of rotation of the turbine. The angle of incidence of the blade depends non-linearly on the rotation angle, the wind speed and the rotation speed. The control optimization method stated in the patent (2) is not based on a proven scientific procedure, and may not provide method convergence. In the patent (2) for the optimization of the angle of incidence of the blade it is proposed to use coefficients of lift and aerodynamic resistance determined by the data measured during the operation of the turbine. This proposal is not feasible because the well-known experimental aerodynamic procedures for determining the above mentioned coefficients require the carrying out of measurements, which cannot be carried out in the operating phase of the above mentioned system.

From the analysis of the literature (1,2) it follows that the turbine under consideration requires significant improvements in the structure, method and control devices.

The present invention proposes the complete solution to the above problems according to claims 1-5. The present invention provides some relevant advantages. One of the main advantages is that the invention makes it possible to increase the efficiency of the conversion of the aforementioned alternative energies into electrical energy, as will be illustrated in detail below. Other advantages, characteristics and methods of use of the present invention will become evident from the following detailed description of some of its embodiments, presented by way of non-limiting example. Reference will be made to the figures of the attached drawings:

Figure 1 shows a side view of a first embodiment of the system;

Figure 2 shows a plan view of a second embodiment of the system; • Figure 3 shows a diagram of the control system;

Figure 4 shows a plan view of the blade with the flap;

• Figure 5 shows a section of the blade with the flap and the relative servomechanism;

• Figure 6 shows a diagram of the resulting velocity, lift and aerodynamic drag vectors of the blade in the first quadrant for K = 1;

• Figure 7 shows the relationship between the angle of incidence a and the angle γ formed between the chord of the blade and the tangential direction τ;

• Figure 8 shows a diagram of the resulting velocity, lift and aerodynamic drag vectors of the blade in the second quadrant for K = 0.5 and K = 1;

• Figure 9 shows a diagram of the resulting velocity, lift and aerodynamic drag vectors of the blade in the second quadrant for K = 1.5 and K = 2;

• Figure 10 shows a diagram of the resulting velocity, lift and aerodynamic drag vectors of the blade in the third quadrant;

• Figure 11 shows a diagram of the resulting velocity, lift and aerodynamic drag vectors of the blade in the fourth quadrant;

With reference to Figures 1 to 5, the system for converting wind or hydraulic energy into electrical energy according to the invention comprises: movable blades (1), which have a center of rotation coinciding with the center of gravity of the section, where each blade ( 1) is equipped with flap (2) with servomechanism (3), which is installed inside the blade (1); each blade (1) is connected to the servomechanism (4), which is fixed to a first rotating disk (5); on the other side the blade (1) is connected through a hinge with a second rotating disk (6); the discs (5) and (6) are connected to each other with rigid bars (7); the planes of the disks (5,6) are parallel to the current lines; the discs (5,6) are installed through bearings (9) and (10) to a fixed rigid axis (8), which is perpendicular to the current lines; the rotor of the electric generator (12) is connected to the hub of the first rotating disk (5), the stator of the electric generator (12) is connected to the fixed axis (8); the axis (8) through the workpiece (13) is fixed to the column (14); the rotating part of the encoder (18) is connected to the first rotating disk (5), the fixed part of the encoder is connected to the piece (13); the wind vane (16) is installed on the axis (8), on the arm of which the anemometer (15) is fixed; the sensor (17) for detecting the wind direction through the rotation of the wind vane (16) is installed on the axis (8); the wattmeter (30) is electrically connected to the generator output (12).

With reference to Figures 6 to 11 we consider the kinematics and dynamics of the system described above. The distance from the center of rotation of the turbine O to the center of rotation C of the blade is R. Suppose the turbine rotates clockwise. Point C will move on a circular path, CQ will be the starting point of the first quadrant of the motion of point C (see Fig. 6). The rotation angle of the turbine is φ. The angular velocity is ω = ~~ ·· The circumferential velocity is equal to ω / ?. The wind speed is U∞. The resulting velocity vector V is equal to the sum of the wind velocity vector and the circumferential velocity vector. The vector V is inclined by an angle ψ with respect to the wind direction.

In the first quadrant:

∞

For all quadrants we consider κ = 0.5; 1.0; 1.5; 2.0.

The aerodynamic lift L can be calculated with the following formula:

where CL is the aerodynamic lift coefficient of the blade, 5 is the area of the blade.

S = bc, where b is the length and c is the chord of the blade.

where oc is effective angle of attack.

For flaps with a string equal to 35% of the blade string

The lift vector L is perpendicular to the vector V. The angle β between the vector L and the radius OC in the first quadrant must be calculated with the following formula:

This formula is valid for all κ values from 0.5 to 2 in the first quadrant.

The angle y between the chord of the blade and the tangential line τ, perpendicular to the radius OC (Fig. 7) must be calculated with the formula:

The moment of the aerodynamic forces in the first quadrant is equal to:

where Ka = -, D is the aerodynamic drag of the blade.

The power produced by the aerodynamic forces is equal to:

average value of the power produced in a quadrant is equal to:

In the second quadrant:

In the fourth quadrant:

Formulas (11), (15) and (16) are valid for the fourth quadrant.

Numerical analysis results

For well known symmetrical NACA profiles, the maximum effective angle of incidence is 11 ° (see (3)). Suppose that the maximum angle of the flap is 20 °, the length of the blade b = lm, the chord of the blade r = 0.2m; 1 = 5. For these data CL = 2.375; S = 0.2m <2>. The variation of the angle γ (φ) for all values of κ is presented in Tables 1,2, 3, 4:

Table No. 1, κ = 0.5

First quadrant

cp, ° 0 10 20 30 40 50 60 70 80 90

γ, ° 11 4.3 -2.33 -9 -15.9 -22.8 -29.9 -37 -44.7 -52.3

Second quadrant

cp, ° 0 10 20 30 40 50 60 70 80 90

y, ° -52.3 -60.7 -69.5 -79 -89.5 -101.5 -115 -131 -149 -169

Third quadrant

cp, ° 0 10 20 30 40 50 60 70 80 90

y, ° -169 -198.5 -218 -234 -247.5 -259.5 -270 -279.7 -288.5 -297

Fourth quadrant

cp, ° 0 10 20 30 40 50 60 70 80 90

y, ° -297 -304 -314 -319.5 -325.5 -333 -340 -347 -353.5 -360

At the end of the fourth quadrant, the servomechanism must turn 360 ° clockwise to be able to function in the next cycle.

Table No. 2, κ = 1

First quadrant

cp, ° 0 10 20 30 40 50 60 70 80 90

y, ° 11 6 1 -4 -9 -14 -19 -24 -29 -34

Second quadrant

cp, ° 0 10 20 30 40 50 60 70 80 90

y, ° -34 -39 -44 -49 -54 -59 -64 -69 -74 -79

Third quadrant

cp, ° 0 10 20 30 40 50 60 70 80 90

γ, ° -79 -84 -89 -94 -99 -104 -109 -114 -119 -124

Fourth quadrant

cp, ° 0 10 20 30 40 50 60 70 80 90

y, ° -124 -129 -134 -139 -144 -149 -154 -159 -164 -169

At the end of the fourth quadrant, the servomechanism must turn 360 ° clockwise to be able to function in the next cycle.

Table No. 3, κ = 1.5

First quadrant

cp, ° 0 10 20 30 40 50 60 70 80 90

γ, ° 11 7 3 -1 -4 -8.5 -12.4 16 -20 -23

Second quadrant

φ, ° 0 10 20 30 40 50 60 70 80 90

γ, ° -23 -26 -29 -31 -31.7 -31 -36 -29 -17 2

Third quadrant

φ, ° 0 10 20 30 40 50 60 70 80 90

γ, ° 2 -7 -20 -27 -30.8 -27.2 -30 -28 -25 -22.5

Fourth quadrant

φ, ° 0 10 20 30 40 50 60 70 80 90

γ, ° -22.5 -19.5 -16 -12.5 -9 -5 -1 3 7 11

Table Νο.4, κ = 2.0

First quadrant

φ, ° 0 10 20 30 40 50 60 70 80 90

γ, ° 11 7.6 4.4 1.1 -2 -5 -8 -11 -23.5 -25.5

Second quadrant

φ, ° 0 10 20 30 40 50 60 70 80 90

γ, ° -25.5 -27.5 -29 -29.5 -29 -27 -23.5 -19.5 -11.5 -1.5

Third quadrant

φ, ° 0 10 20 30 40 50 60 70 80 90

Υ, ° -1.5 1 -7 -13 -17 -18.5 -19 -18.7 -17 -15

Fourth quadrant

φ, ° 0 10 20 30 40 50 60 70 80 90

γ, ° -15 -13 -11 -8 -5 -2 1 5 8 11

Suppose that the conversion efficiency of mechanical energy into electrical energy through the generator, including friction losses, is η = 0.85. The power that the turbine with four blades can produce can be calculated as the sum of the powers produced in quadrants from 1 to 4:

The mean moment of the aerodynamic forces can be calculated by the formula:

For a reference speed (standard) of 12m / sec, the data of the power that the turbine can produce for different values of κ, are presented in table No. 6.

Table No. 6

κ 0.5 1.0 1.5 2.0

I ^ kW 0.52 1.2 2.2 3.36

We calculate the wind speed, for the different values of κ:

From (52) and (53) it follows:

Table No. 7 presents the data of the wind speed necessary to produce a power W = 1VSN.

Table No. 7

κ 0.5 1.0 1.5 2.0

U∞, m / sec 15 11.3 9.22 8

iùR, m / sec 7.5 11.3 13.83 16

RPM (/? = 0,5m) 143 216 264 306

The system according to the present invention is much more compact and more efficient than the best wind turbines available on the world market. For example, an Excel system with a power of 1kW, produced by Bergey Wind Power (4), has a turbine diameter of 2.5m. The swept area of this turbine is 5 times larger than the system according to the present invention.

A second embodiment of the system under analysis can be that of a system capable of converting the energy of a current of water, which can be used in a sailboat for powering the electronic navigation devices and auxiliary electrical devices. Suppose this hydraulic turbine has 4 blades, and each blade has dimensions Z? = 0.5m, c = 0, lm. This hydraulic turbine would be capable of producing 2.65 kW for a boat speed of 18 km per hour.

Conclusion

The system according to the present invention has significant advantages when compared with existing wind turbines. The system can be realized in wind or hydraulic form.

Literature

l.ln Seong Hwang et al.

Efficiency improvement of a new vertical axis turbine by the individai active control of biade motion.

2006 SPIES. 6173..316H

2.U.S. Patent No: 8,193,657

Vertical axis wind turbine using individai biade pitch and camber control integrated with matrix converter

Inventors: Paluszek, Michael A., Bhatta, Pradeep.

Assignee: Princetone Satellite Systems.

3. W.A. Timmer

Two dimensionai low-Reynolds number wind tunnel results for airfoil NACA 0018

Wind Engineering, Volume 32, No. 6, 2008, pp 525-537.

4.www. allsmallwindturbines.com/midden.htm

Claims (6)

CLAIMS 1. A system for the conversion of wind or hydraulic energy into electrical energy, comprising: mobile blades (1), which have a center of rotation coinciding with the center of gravity of the section, where each blade (1) is equipped with a flap (2) with servomechanism (3), which is installed inside the blade (1); each blade (1) is connected to the servomechanism (4), which is fixed to a first rotating disk (5); on the other side the blade (1) is connected through a hinge with a second rotating disk (6); the discs (5) and (6) are connected to each other with rigid bars (7); the planes of the disks (5,6) are parallel to the current lines; the discs (5,6) are installed through bearings (9) and (10) to a fixed rigid axis (8), which is perpendicular to the current lines; the rotor of the electric generator (12) is connected to the hub of the first rotating disk (5), the stator of the electric generator (12) is connected to the fixed axis (8); the axis (8) through the workpiece (13) is fixed to the column (14); the rotating part of the encoder (18) is connected to the first rotating disk (5), the fixed part of the encoder is connected to the piece (13); the wind vane (16) is installed on the axis (8), on the arm of which the anemometer (15) is fixed; the sensor (17) for detecting the wind direction through the rotation of the wind vane (16), is installed on the axis (8); the wattmeter (30) is electrically connected to the generator output (12). System according to the preceding claim, where the sensors (15), (17), (18), (30) are connected through cables to the computer P, which is installed outside the rotating part of the system; the servomechanisms (4) of each blade and the servomechanisms (3) of each flap are connected to an Rx radio control receiver, which is installed on one of the rotating discs (5 or 6); the computer P is connected with the receiver Rx through a radio transmitter Tx, which is installed outside the rotating part of the system. System control method according to the preceding claims, wherein: a) the actual angle of attack between the blade chord and the resulting velocity vector must be constant for each blade in any blade position during the operating cycle regardless of wind speed and regardless of turbine rotation speed; b) in real time the processor P takes data from sensors (15), (17), (18): wind speed U∞, directional angle of the wind, angle φ of rotation of the turbine with respect to the fixed axis (8) ; - the processor calculates for each angle φ the processor also calculates the angle ψ of inclination of the vector V of the resulting speed with respect to the wind direction, after which it calculates the angle y formed between the chord of the blade and the tangential direction τ; this procedure is repeated for each blade; c) in real time the processor P takes the data from the wattmeter (30), calculates the average power W for at least 10 cycles and stores this value; d) in real time for each angle φ the processor P sends commands to the servomechanisms (4) to increase the value of the angles γ by a value Δγ, which must be the same for each φ and for each blade, after which the procedure indicated is repeated in point c); if the power W has increased, the procedure for increasing γ and the procedure referred to in point c) are repeated; if the power W has decreased, the processor P sends commands to the servomechanisms to decrease γ by a value Δγ, returning to the previous values of γ; processor P stores all the data for use in similar conditions. 4. System according to the preceding claims, in which each flap has a constant angle δ of inclination with respect to the chord of the blade; the processor P sends a command to the servomechanism (S) of the flap to change the sign of the angle δ when the sign of the effective angle of attack of the blade changes. 5. System control method according to the preceding claims, in which in real time the processor P sends commands to the servomechanisms (S) to increase the angles δ by a value Δδ, which must be the same for each φ and for each blade; then in real time the processor P takes the data from the wattmeter (SO), calculates the average power W for at least 10 cycles and stores this value; if the power W has increased, the procedure for increasing δ and the procedure for measuring the power W are repeated; if the power W has decreased, the processor P sends commands to the servomechanisms to decrease δ by a value Δδ, returning to the previous values of δ; processor P stores all the data for use in similar conditions. The group of systems according to the preceding claims, comprising at least two counter-rotating systems (A) and (B) installed on the two arms (20) of a structure fixed through the bearing (23) to the column (20); the structure indicated above is equipped with an aerodynamic rudder (24), the plane of which it belongs to is perpendicular to the plane containing the axes of the arms (20); these axes coincide with the straight lines passing through the centers of rotation of the two aforementioned systems.