RU2664639C2 - Method for converting the kinetic energy of a air flow to a rotary movement of a blade - Google Patents

Abstract

FIELD: energy.SUBSTANCE: invention relates to the field of non-conventional energy. Method of converting the kinetic energy of the air flow into rotational motion of the blade is that wind power plant comprises a wind receiving device made in the form of a wind wheel mounted rotatably about a vertical axis and provided with blades mounted on shafts located on the axis of symmetry of the blades, at that the shaft of each blade being connected coaxially with the shaft of its own electric drive, its structure includes the control unit, that turns the corresponding blade, and with the rotational motion of each flat blade in a circular orbit, the position of its plane is set by means of an electric drive with a position sensor of the driving blade shaft at turning angle β with respect to the direction of the air flow at each point of the circular trajectory of its shaft, upon command from its control unit, performing a continuous analytical calculation of this angle β=α/2+45 ° from information on angle α rotation of the vertical axis relative to the airflow vector obtained from the air flow direction sensors and the angular position of the vertical axis of the wind power plant relative to the airflow vector, and for the remaining blades, constant angle corrections are introduced into corresponding control units α 180, 120 or 90 degrees depending on the number of blades.EFFECT: invention is aimed to increase the power of the wind power plant.1 cl, 3 dwg, 1 tbl

Description

The invention relates to the field of alternative energy and can be used as a source of electrical and mechanical energy in hydro and wind turbines, in particular in the construction of wind receiving devices with the axis of rotation of the rotor perpendicular to the direction of air flow (VP). The proposed method for converting the kinetic energy of the VP into rotational motion with a flat blade provides the optimal angle of rotation of the blades with respect to the direction of the vector of the blades when moving along the circular path of their axes and maximum energy efficiency for this type of wind power plants (wind turbines).

As an analogue, we consider a known rotary wind turbine according to patent RU 2380567 C2, IPC F03D 3/00 dated 01/27/2010, in which the wind turbine comprises an impeller mounted on a vertical shaft, made in the form of rotary blades mounted between the upper and lower rims mounted on the brackets associated with the shaft coupled to the electric generator, and the blade control mechanism, each blade equipped with a blade control mechanism in the form of a weather vane and a rotary device mounted coaxially with the vertical shaft fall off, and the rotating device consists of a differential, one shaft is rigidly connected to a wind vane axis, a second shaft fixedly connected with the rim of the impeller, the differential housing is rigidly connected with the rotary axis of the blade.

1. The disadvantages of the known device are a rather complex implementation mechanism and its large metal consumption, and the transfer of mechanical energy from part 12 to part 13 by friction during operation will not be reliable.

2. The position of the blades relative to the airflow vector is indicated in the patent description. In the 1st quadrant - 45 degrees - the position is correct, in the 2nd - 90 degrees - correct, in the 3rd quadrant - 135 degrees, which is true only for the first half of this quadrant, and in the second half of the 3rd quadrant the position of the blade, a braking moment will occur, which means that the blade does not work correctly, in the area of 270 degrees the blade occupies a position of 180 degrees relative to the airflow vector (winds), and in the 4th quadrant it moves at a certain sharp angle to the airflow vector. As you can see, the blade is controlled according to a rather complicated law, moreover, with an error in the 3rd quadrant and an indefinite value of the acute angle in the 4th. Achieving such results only with the help of a differential gearbox is problematic, but the author does not disclose the know-how. It is not possible to use a wind turbine according to this patent without additional information.

A known design of a wind turbine with a wind wheel "Wind turbine rotary-type installation with cyclically smoothly rotating, in antiphase rotor, symmetrical blades" according to patent RU 2392490 C1, IPC F03D 3/00, dated 20.06.2010, adopted as an analogue. A rotary-type wind power installation with symmetrical blades rotating cyclically smoothly in antiphase to the rotor, containing blades mounted on axes parallel to the rotor axis of rotation, and equipped with rotary drives for rotating the blades around its axis, ensuring their smooth half-turn rotation in the opposite direction relative to the direction of rotation of the rotor with its full revolution around its axis, the drives can be either mechanical, working through a mechanical connection with oriented directionally gears of the wind, or sprockets also oriented in the direction of the wind and blocked by the number of chains on the central axis of the rotor, or by electric drives for rotating the blades around their axes, while electronic commands from wind sensors of the wind vane and anemometer located on the wind power installation are either given to the actuator adjustments to the wind direction of the central gear located on the rotor axis, or interlocked mechanical drive sprockets located on the rotor axis, or on electric water rotation of the blades around its axes.

This design provides a satisfactory value of the coefficient of utilization of wind energy, allows you to install blades of any design. However, this technical solution is not able to eliminate a number of negative features inherent to varying degrees with most known wind turbine designs. These include:

1) difficult to operate and unreliable option with mechanical drives, sprockets and a set of chains;

2) an intuitive method for obtaining wind flow energy (without real mathematical calculations) is proposed that is far from a rigorous method for obtaining the maximum possible (extreme) energy of each blade from the air flow when it moves along a circular path (0-2π) - mathematically at any point on this path , except for the point of passage alone, with maximum speed towards the wind, when the windage of the blade relative to the wind is practically zero, all the blades act with the same moment of force on the rotor. And at the point of maximum disclosure of the sailing of the blades under the wind force vector, while traveling in the wind, the moment of force created is also maximum at this point, because at this point the driving force of the blade has the longest shoulder;

3) it is not clear how electronic commands from wind sensors of a wind vane and an anemometer located on a wind power installation are joined with a central gear located on the axis of the rotor, or interlocked sprockets of a mechanical drive located on the axis of the rotor, or on electric drives for rotating the blades around their axes (section AA, with a side view), the vertical axis of the APU, interlocked sprockets, with a weather vane, a wind sensor, a blade correction mechanism for wind direction;

4) the energy of the air flow is not used at all when the blades move towards the air flow - a cowl-cowl is installed on the installation, which covers part of the rotor from the wind where the inverse movement of the blades is inverted towards the wind, made with the possibility of throwing air flows out of the casing -the fairing of the blade and oriented in the direction of the wind through the central gear or interlocked sprockets on the axis of the rotor;

5) offers obviously unrealistic, fantastic solutions, where in FIG. 6 of the patent shows a side view of an airship anchored to the ground with the paired APU of the present invention suspended from it;

6) in the blade-plane mode, its optimal speed is 1/3 of the air flow velocity, i.e. the wind turbine should be low-speed, and in the wing mode (of dubious configuration) its lifting force depends on the speed of the resulting air flow and the angle of attack. At low speeds and a non-optimal angle of attack, the effectiveness of such a wing will be very low;

7) the need to turn the entire rotor together with the mechanism of rotation of the blades when focusing on changing the direction of the wind.

A known design of a wind turbine with a wind wheel "Wind turbine" according to patent RU 2543905 C2, IPC F03D 3/00 of 03/10/2015, adopted as a prototype. The wind power installation contains a wind receiving device made in the form of a wind wheel mounted rotatably around a vertical axis and equipped with blades located on the rim of the wind wheel and mounted on shafts located on the axis of symmetry of the blades, the shaft of each blade being connected coaxially with the shaft of its own drive, making a turn the blades, and the wind wheel of the wind receiving device is made in the form of an oblique section of the cylinder with a maximum height of the longitudinal diametrical section tions at least twice the height of the blades. Note the shortcomings in the design, operation and execution of the patent adopted for the prototype.

1. The design has apparently two wind wheels pos. 1 and pos. 2, located at an angle to the main shaft, numbered in the same way as the blades pos. 2, as well as the drive pos. 5 and the microcontroller, also indicated by pos. 5, but the details of mounting to the shaft are missing.

2. In the proposed design with rims at an angle, the area of each blade is 2 times smaller, and the shading effect is not eliminated. The proposed more complex design requires an increase in the number of blades and drives to them, i.e. unjustified complication and increase in value.

3. In the description and in the claims, the shape of the blades is not indicated. If flat blades are used, then unrealistic operating air flow rates and wind turbine speed are outlined (at angular speeds up to two or three revolutions per second and blade area up to 5 m ² ). For flat blades, the “Grag Principle” principle of drag is used, based on the ability to receive energy from the airspace only by moving the body into the airspace. The air flow, according to the direction, is determined by the projection of the pressure gradient for the entire area of the elements relative to the braking force of the profile with respect to the VP [Rozin MN Theory of sailing installations. http: /rosinmn.ru/vetro/teorija_parusa/teorija_parusa.htm].

If the plate is stationary and perpendicular to wind speed, then force acts on it

Where

F is the pressure force of the air flow [n],

C _x - coefficient of resistance, depending on the shape of the body,

p is the density of air 1.29 [kg / m ³ ],

S is the cross-sectional area of the plate [m ² ],

V _in - air velocity [m / s].

The coefficient C _x depends on the shape of the body. A thin large plate is perpendicular to the flow C _x = 1.33.

When the plate moves, it runs away from the wind and the relative speed of the air flow incident on the plate decreases. Therefore, the pressure force of the air flow will also be less

where V _p is the speed of the plate.

If the plate is stationary, then the net power is zero. If the plate moves with wind speed, then it does not experience pressure, and the power is also zero. To achieve the maximum coefficient of utilization of wind energy (KIEV), the speed of the plate should be three times less than the speed of the wind. For a flat plate KIEV is 0.164-0.197. For example, with a diameter of D = 4 m, i.e. the distance between two opposite axes, pos. 3 blades, pos. 2 for 1 revolution, the axis of each blade passes the path π D = 12.5 m, and for 0.5 seconds according to the description, i.e. it is assumed that when optimizing the installation speed (1/3 V _in ) V _in = 75 m / s

4. From the description of the patent, the following wording is not clear: "Due to the fact that the blades moving against the wind and in the wind occupy a" position with an edge "towards the wind, they do not create aerodynamic drag and allow the blades to have a velocity vector module greater than the wind speed." The wings in the "edge position" actively work, and the moments for positions A and E of FIG. 3 prototypes are directed towards. If these are flat blades, then they cannot outrun the wind speed without additional external influence.

5. In FIG. 3 prototypes given 8 positions of the blades (presumably flat), which relative to the air flow vector should provide the maximum energy transfer to the generator. However, in the positions of both H, A, and E, the blades give a zero moment, as for the other 5 positions of the blade, although the direction of the moment is correct, it is not clear how optimally the angle between the air flow vector and the blade is chosen (experimentally or analytically) and how will be shown in the technical proposal, far from a strict optimum.

The technical result of the proposed method lies in the maximum efficiency of converting the kinetic energy of airborne air into electrical energy. It is achieved by the fact that in the proposed method, the axis of each blade is connected to the shaft of its own drive, performing a turn of each flat blade in a circular orbit, the position of its plane is set using an electric drive with a position sensor of the shaft of the driving blade at a rotation angle β relative to the direction of the air flow at each point the circular trajectory of its shaft on command from its control unit, performing continuous analytical calculation of this angle β = α / 2 + 45 ° according to information about the angle α of rotation of the vertical axis relative the airflow vector obtained from the airflow direction sensors and the angular position of the vertical axis of the wind turbine relative to the airflow vector, and for the remaining blades, constant corrections are introduced into the corresponding control units for the angle α 180, 120 or 90 degrees depending on the number of blades.

Increasing the power of a wind turbine is also carried out by maintaining the speed of the blades in a circular motion about 1/3 of the speed of the main vector of the VP by controlling the load of the generator associated with the axis of the wind turbine through a gearbox or variator. The increase in the power of the wind turbines is also facilitated by the fact that the airflow entering the wind turbines is limited by the upper and lower disks, which are rigidly fixed on the vertical axis of the wind turbines and increase the density of the airplanes on each blade, since there is no slipping of the VP from the upper and lower parts of the blades.

The aim of the invention is to increase the power removed from the unit "swept" area, and efficiency in the zone of low speed VP (1.5-4 m / s), low speed 10-30 rpm, which helps to reduce the cost and increase the reliability of the bearing assemblies of the axis of the wind turbine , as well as reducing spurious noise and vibration, which positively affects the environment. In addition, the placement of the blades and their axes between the disks compacts the VP directed to the blades (there is no slipping of the VP from the upper and lower parts of the blade), increases the rigidity and reliability.

In FIG. 1 shows a design variant of a wind turbine implementing the proposed method.

In FIG. 2 illustrates the method of obtaining the maximum moment for a wind turbine with flat blades.

In FIG. 3 gives eight positions of the blade with one revolution of a wind turbine.

A wind power installation consists of a number of parts and components:

- an electromechanical converter unit 1, the generator of which is connected through a gearbox or variator with a vertical axis 7, the rotational axis 2 and VP 11 speed sensors are connected to the unit’s inputs, and an industrial network or a group of high-capacity batteries (with inverters operating for industrial network), frame 3, provides a rigid vertical position of the entire design of the wind turbine, it is on it that the speed sensor 11 is placed, for example an anemometer;

- the axis of the wind turbine 7, on which the supporting discs 4 and 6 are rigidly fixed using nuts 8, and the axis 7 below is connected to the frame 3 with the help of the lower support 9;

- the angular position sensor 10 of the axis 7 and the weather vane 12 are attached from above to the axis 7, the stator of the sensor 10 is rigidly connected to the axis 7, and its rotor is rigidly connected to the axis of the weather vane 12;

- flat blades 16 are mounted on the shafts 14;

- cases of electric drives 15 with integrated control units and position sensors of the shafts 14 are mounted on the lower disk 4, and the shafts of the electric drives 15 are rigidly connected to the shafts 14 of the flat blades 16;

- each shaft 14 is connected to the supports 17 located on the upper disk 6.

Block 1 of the electromechanical converter maintains the speed of the wind turbine about 1/3 of the speed of the VP due to the regulation of the load of the generator up to its rated load. In this case, block 1 generates at the generator output such a load that provides a linear speed ωR when the shafts 14 of the blades 16 move in a circular orbit equal to 1/3 of the speed of the VP. R is the distance between the axis 7 and the shafts 14, and ω is the angular velocity of the shafts 14 (see Fig. 2). The speed of the blades in a circular orbit, i.e. the rotation speed of the shafts of the blades around the axis 7 along the working circle (RO) is determined by its RPM sensor 2, and the speed of the main VP is determined by the speed sensor of the VP 11. In connection with the movement of the shafts 14 of the blades 16 along the PO, an additional VP vector is applied to each blade 16, directed along the tangent to RO and the resulting air flow is either larger or smaller than the main airspace vector. In connection with the low revolutions of the wind turbine under consideration, the presence of several blades, we neglect the influence of an additional VP and choose the speed of the shafts of 14 blades 16 along the RO equal to 1/3 of the current speed of the main VP.

The VP entering the wind turbine is limited by the upper 6 and lower 4 disks, which are rigidly fixed on the axis 7 and increase the density of the VP on the blades 16, while there is no slipping of the VP from the upper and lower parts of the blade 16. The position of the blades 16 is controlled by the electric drive 15 taking into account the position sensor and control commands from the control unit of the electric drive 15 based on information about the angle α of rotation of the vertical axis 7 relative to the airflow vector of the airflow, determined by the vane 12, obtained from the sensors of the air flow direction and the angular position of the vertical axis a wind turbine relative to the airflow vector.

With several blades of a wind turbine, constant corrections for the angle α 180, 120 or 90 degrees depending on the number of blades are introduced into the corresponding control units of the electric drives 15. With sub-extreme regulation (see Fig. 2 and Fig. 3) relative to the airspace vector using the sensor 10 of the vane 12 and electric drive 15, the plane of the blades 16 is set at a certain angle β relative to the airspace vector at each point of movement along the PO. Sub-extreme regulation is optimization without taking into account the additional VP arising from the rotation of the blades in a circular orbit.

This ensures the maximum possible moment of rotation for each value of the angle of rotation α of the axis 7. With sub-extreme control, the pressure of the VP on the blades 16 should not significantly exceed a certain calculated nominal value, which is defined in block 1 as the nominal load of the generator. In order to optimize revolutions, a unit of an electromechanical converter 1 is introduced into the wind turbines, which generates such a load at the generator output that provides a linear speed of the shafts of the flat blades of the wind power installation when it moves in a circular orbit equal to 1/3 of the air flow velocity.

In the present invention, two principles of optimization of the conversion of the kinetic energy of VP are used simultaneously:

1. Optimization of the position of the flat blade 16 relative to the VP vector during the movement of its shaft 14 along the RO and obtaining the maximum moment up to the rated load of the generator at each point of this trajectory. Analytical expressions are obtained without taking into account the additional vector of the VP arising from the rotation of the blades along the RO.

2. Optimization of the speed of the plane along the circular path of the proposed design of the wind turbine, using the principle of drag "Grag Principle". For example, at a speed B equal to 6 m / s, with a corresponding load on the generator, we obtain a shaft speed of each wind turbine blade of 2 m / s in PO, i.e. 1/3 of the speed of the VP.

In FIG. Figure 2 illustrates the method for obtaining the maximum moment M = Fh, where F is the force created by the VP on the blades 16, h is the shoulder of this force relative to axis 7 for a wind turbine with flat blades. The relationship between the rotation angle α of the axis 7 relative to the vector of the VP and the angle of the plane β of the blade 16 relative to the vector of the VP is found. The projection S of the blade 16 on a plane perpendicular to the vector VP (see Fig. 2) is at an angle Q and is equal to:

where S ₀ = blade area.

When optimizing the speed of rotation of a wind turbine, i.e. the velocity of the axes of the blades along the RO, V _P = 1 / 3V _B , and the pressure force F on the blade taking into account (2):

We define the moment that the force develops according to (4) (see Fig. 2) relative to the axis of the wind turbine 7. The shoulder h depends on the distance R between the axis 7 and the shaft 14 of the blade 16 and is equal to:

Taking into account (4) and (5), the moment M _L of the wind turbine rotation created by each blade 16 at each point of the blade of the blade

It is necessary for each value of the angle α when the blade moves along a circular path to find the maximum value of the moment, which obviously depends on the angle β, which determines the position of the plane of the blade relative to the VP vector. We take the derivative from the moment M _L β

Therefore, Cos (2β-α) = 0.2β-α = 90 °, and we obtain the main analytical expression for the developed wind turbine

The relationship between the angles β and α according to (8) in a wind turbine provides the maximum value of the moment at any point of the PO of each blade 16.

In FIG. 3, eight positions (A, B, C, D, G, E, H, K) of the blade 16 are given for one revolution of the wind turbine, taking into account the obtained optimal ratio between the angles α and β relative to the VP vector and the maximum energy E _Л obtained from the air flow one revolution of one blade.

The table shows the values of the angles α and β for eight positions of the blade 16 at β = α / 2 + 45 °:

At the initial time, the wind turbine is stationary, however, the control units and position sensors of the shaft 14 of each electric drive 15 with the corresponding program implement the analytical expression (8) of the relationship between the angle α of rotation of the vertical axis 7 relative to the air flow vector and the angle β of rotation of the shaft 14 of each blade 16 relative to the vector VP at each point of RO. In this mode, each control unit of the electric drives 15 receives information from the weather vane 12 and from the position sensor 10, calculating the angular position of the blades 16 relative to the position of the weather vane 12. When changing the direction of the air conditioner, the corrected angle commands α and calculated for the angle β will be transmitted to the control units of the electric drives 15, those. the new position of the blades 16 relative to the vector VP. This technique is described for one blade, called the leading. For the remaining blades 16, constant corrections are introduced into the control units of the electric drives 15 for the angle α 180, 120 or 90 degrees depending on the number of blades. At stormy wind speeds creating hazardous operation modes for a wind turbine, on the signal from the VP speed sensor 11, the electric drive control units 15 put all the blades into the weather vane mode. In this position, the incoming air flow does not create torque on the blades 16 and the wind turbine is in passive mode.

Claims (2)

1. The method of converting the kinetic energy of the air flow into the rotational movement of the blade, which consists in the fact that the wind power installation containing a wind receiving device made in the form of a wind wheel mounted for rotation around a vertical axis and equipped with blades mounted on shafts located on the axis of symmetry of the blades moreover, the shaft of each blade is connected coaxially with the shaft of its own electric drive, which includes a control unit that performs a corresponding turn blades, characterized in that during the rotational movement of each flat blade in a circular orbit, the position of its plane is set using an electric drive with a position sensor for the shaft of the driving blade at a rotation angle β relative to the direction of the air flow at each point of the circular path of its shaft by command from its control unit, performing continuous analytical calculation of this angle β = α / 2 + 45 ° according to information on the angle α of rotation of the vertical axis relative to the air flow vector received from the air direction sensors shnogo stream and the angular position of the vertical axis wind power installation relative to the vector of the air flow, and for the remaining blades to the corresponding control units are input to the constant correction angle α of 180, 120 or 90 degrees depending on the number of blades. 2. The method according to p. 1, characterized in that an electromechanical converter unit is introduced into the wind power installation, which generates such a load at the generator output that provides a linear speed of the shafts of the flat blades of the wind power installation when it moves in a circular orbit equal to 1/3 of the air speed flow.

Images