RU2118699C1 - Wind-power plant and its operation - Google Patents

Abstract

FIELD: conversion of wind energy into useful energy. SUBSTANCE: radial cylinders of wind-power plant with horizontal axis of revolution are built up of rotating tail part and fixed root part. Each cylinder is provided with two vortex generators. In first design version, vortex generators are arranged along cylinders with angular coordinates relative to wind direction being φ₁ = 45^o,φ₂= -90^o.; according to second version, vortex generators are installed over spiral and their angular coordinates relative to wind direction are

Description

 The invention relates to wind energy and relates to wind turbines with rotating cylinders using the Magnus effect for operation. The latter is characterized by the appearance of a lifting force (Magnus force) when the cylinders rotate in a transverse flow [1]. This force is used to rotate the wind wheel, similar to the lifting force of the blade, but has a much larger value.

A known method of creating lifting force on a non-rotating cylinder using add-ons installed on it along one of the sides and having a semicircular shape [2]. Such superstructures create an asymmetry of the transverse flow around the cylinder, which causes the appearance of a lifting force that is comparable in magnitude with the lifting force of the blade. The maximum value of this force is achieved when the superstructures are located directly on the surface of the cylinder at points 90 ^o or -90 ^o , counted from the direction of the wind, while the force acts in the direction opposite to the location of the superstructure.

 A known installation is a rotor of a wind turbine with a horizontal axis of rotation, containing radial cylinders with superstructures in the form of plate-type spoilers installed along one of the sides of the cylinders. Cylinders have the ability to rotate around their axes [3].

 The disadvantages of this installation are: limited opportunities for self-starting and self-regulation of the operation of the wind wheel, including for stabilizing its rotation at high wind speeds; limited possibilities for increasing the length of the rotating cylinders and, consequently, the diameter of the wind wheel; insufficiently high power due to the limited diameter of the wind wheel; increased power consumption for the rotation of long cylinders. The objective of the invention is to increase the efficiency and power of the wind turbine, as well as the possibility of aerodynamic self-starting and self-regulation under any operating conditions, without additional energy costs, in a wide range of wind speeds, including storm ones.

The task is carried out on a wind turbine with a horizontal axis of rotation of the wind wheel, the radial cylinders of which are made up of a rotating end and a non-rotating root part, and each of the cylinders is equipped with two turbulators in the form of tubes located along the cylinders on its opposite sides, and it is asymmetric with respect to the direction of the wind with angular coordinates
φ ₁ = 45 ^o and φ ₂ = -90 ^o
The presence of two turbulators (instead of one according to [2, 3] provides the appearance of a total aerodynamic force, which allows more efficient start-up and regulation of the wind wheel. At the same time, self-start and self-regulation of the work, up to maximum (storm) wind speeds, take place. created on the cylinders under the action of turbulators, when the rotational speed of the wind wheel deviates from the calculated (specified). As a result, a compensating force appears, which restores It increases the calculated (predetermined) rotational speed of the wind wheel. Self-regulation with the help of turbulators is supplemented by regulation by changing the speed of the cylinders. At the same time, with the increase in wind speed, the influence of turbulators increases, and the effect of cylinder rotation decreases, on the contrary, the installation works only due to turbulators, without cylinder rotation, which significantly expands the capabilities and effectiveness of this installation.

 The use of composite cylinders with a rotating end and non-rotating root parts can significantly increase the power of the wind turbine, as well as its effectiveness. The increase in power is achieved by adding a non-rotating root part, which allows to increase the total length of the cylinders and, consequently, the diameter of the wind wheel, and the power is proportional to the square of the diameter. In this case, rotating cylinders with a large lifting (driving) force are used more efficiently, because located at a greater distance from the axis of rotation of the wind wheel and, therefore, create a higher torque. Non-rotating cylinders in the presence of turbulators also create a torque that increases with increasing diameter and length of these cylinders.

 In the presence of a non-rotating root part, the power consumption for the rotation of the end cylinders is simultaneously reduced due to a decrease in their length relative to the full length of the cylinders. In addition, such a wind wheel has increased strength, which is determined by the circular, most durable shape of the cylinder and the increased diameter of its non-rotating part, as well as the low speed of the wind wheel (approximately 5 times lower than the blade).

 These features are not identified in other technical solutions when studying the level of this technical field and, therefore, the proposed solution is new and has an inventive step. The proposed technical solution is industrially applicable, in particular, in wind energy.

In FIG. 1 shows a General view of the wind turbine; in FIG. 2 is a diagram of an arrangement of longitudinal turbulators in section AA in FIG. 1; in FIG. 3 - the lifting coefficient of the non-rotating cylinder depending on the angular position of the turbulator T ₁ (experimental data ITPM); in FIG. 4 - also with turbulators T ₁ and T ₂ at different Reynolds numbers (ITAM data); in FIG. 5 - influence of the Reynolds number on the lift coefficient of a cylinder with turbulators T ₁ (curve C ₁ ) and T ₂ (curve C ₂ ) at φ ₁ = 45 ^o and φ ₂ = -90 ^o (light icons - ITAM data, dark icons - data [2]; in Fig. 6, also for the total lift coefficient; in Fig. 7 is a diagram of the flow around a cylinder with turbulators T ₁ and T ₂ under starting conditions (without rotation of the cylinders and wind wheel); in Fig. 8 is also on the calculated operating mode of the wind wheel; in Fig. 9 - the frequency of rotation of the wind wheel, depending on parameter Q - the relative speed of rotation of the cylinders, from turbulize tori (curve 9) and without them (curve 10) with the number Re = 0.7 • 10 ⁵ (ITAM data).

The wind turbine (Fig. 1) contains a wind wheel with a horizontal axis of rotation, which is mounted on a fixed support (tower) and can be rotated on it in the direction of the wind (similar to traditional schemes). The wind wheel consists of a housing 1 with front and rear fairings, a non-rotating part of the cylinders 2 and a rotating part 3 with end washers 4, which limit the unwanted flow of the stream. The length of the rotating part of the cylinders is L _in = αL, for the non-rotating part, respectively, L _n = (1-α) L, where L is the total length of the cylinder, α = 0.4-0.6. The diameter of the non-rotating part of the cylinders is 1.5 to 2 times larger than that of the rotating part.

 The end parts of the cylinders are thin-walled shells that are seated on a cantilever shaft through bearings and rotate from individual electric drives located on the shaft end (not shown in the drawing). The shaft is mounted cantilever to the end of the fixed part of the cylinders. The electric drive receives power from the wind generator. Backup power - from the battery. The generator rotates from the wind wheel through a multiplier that increases the speed to the values necessary for the generator to work.

In FIG. 2 shows the arrangement of turbulators T ₁ - 5 and T ₂ - 6, which are installed along each cylinder and made in the form of tubes with a diameter of d _t = (0.1 - 0.02) d and a length of L _t = L _n + aL _in , where d is the cylinder diameter, a = 0.2 - 0.8 (depending on the design and nature of the wind turbine). The distance from the surface of the cylinders to the turbulator T ₁ is h ₁ = (0.1 - 0.2) d, to the turbulator T ₂ is h ₂ = 0 - on the non-rotating part and h ₂ = (0.02 - 0.05) d - near the rotating part of the cylinders. The angular position for the turbulators T ₁ and T ₂ is respectively φ ₁ = 45 ^o and φ ₂ = -90 ^o , where the angles φ ₁ and φ _{2 are} measured from the front critical point of the cylinders (from the wind direction), and φ ₁ is in the direction of rotation cylinders, φ ₂ - vice versa.

The operation of the wind turbine is largely dependent on the turbulators T ₁ and T ₂ . The mechanism of their influence is quite complicated. Let us dwell on it in more detail. The purpose of the turbulizers is to create an aerodynamic force Y _t - in addition to the main Magnus force Y _m that occurs when the cylinder rotates (see Fig. 1). The force Y _t in contrast to Y _m occurs on a non-rotating cylinder, and its value decreases with rotation of the cylinder. The source of the appearance of the force Y _t is the asymmetry of the flow around the cylinder due to the asymmetric arrangement of the turbulators, namely, φ ₁ <| φ ₂ |, h ₁ ≫h ₂ , with φ ₂ __ → 90 ^o , h ₂ __ → 0. Under these conditions, the influence of the turbulizer T ₂ affects in its immediate vicinity, causing a flow separation directly behind the turbulator. The turbulizer T _1, in contrast to T _2, acts not locally, but through relatively long transition-separation processes in the boundary layer of the cylinder (transition from the laminar state to the turbulent one with intermediate stages, with the formation of the so-called separation bubble - a closed region between the points of laminar separation and attachment the boundary layer in a turbulent state, after which the final separation of the flow occurs). As a result, the flow separation point under the influence of the turbulator T ₁ is shifted up to the angle φ _er = 130-140 ^o , and under the influence of the turbulator T ₂ it is fixed near the angle φ _er = -100 ^o [2], asymmetry flows around the cylinder with the appearance of the force Y _t directed towards lower pressure (where the separation point is shifted further downstream). The force Y _{t is} used when starting a wind wheel, including without cylinder rotation, and for self-regulation of the wind turbine when deviating from the design mode.

Below are the test results of a cylinder with turbulators in the ITPM wind tunnel. In FIG. 3 shows a graph of the lift coefficient C _y for a non-rotating cylinder as a function of the angular position of the turbulator T ₁ around the cylinder, and FIG. 4 - also for turbulators T ₁ and T ₂ . Here, C _y = Y _t / q • S, where q = ρV ^2/2 - velocity head, S = d • L _t - area, ρ- air density. It can be seen that the coefficient C _у depends on the magnitude and sign of the installation angle of the turbulator. When you change the sign of the angles φ ₁ and φ _{2, the} coefficient C _y is reversed. The maximum positive values of C _{y are} achieved in the region of φ ₁ = 30-50 ^o and when φ ₂ = -90 ^o
The coefficient C _у also depends on the Reynolds number, which is expressed as Re = V • d / ν, where ν is the coefficient of kinematic viscosity of air. In FIG. Figure 5 shows the experimental data for the components of the coefficient C _у from the action of the turbulator T ₁ (curve C ₁ ) and the turbulator T ₂ (curve C ₂ ) depending on the number Re at the angles of installation of the turbulators φ ₁ = 45 ^o and φ ₂ = -90 ^o .

Here, light icons indicate ITAM data, dark icons indicate data [2]. From the graphs it can be seen that the coefficient C _{2 is} always positive, and the coefficient C ₁ changes its sign to the opposite when passing through the critical number Re _cr = 5 • 10 ⁵ .

The noted behavior of the coefficients C ₁ and C ₂ significantly expands the possibilities for self-starting and self-regulation of the wind wheel in relation to the variant with one turbulator T ₂ (prototype). This follows from the graph in FIG. 6, which shows the total value of the coefficient C _Σ = C ₁ + C ₂ depending on the Reynolds number (angles φ ₁ and φ ₂ are the same as in Fig. 5). For subcritical numbers Re <Re _cr = 5 • 10 ^{5, the} coefficient C _Σ > C ₂ , that is, we have an increase in C _Σ with respect to C ₂ due to C ₁ , which improves the start of the wind wheel and operation at wind speeds up to 10 - 20 m / c corresponding to the indicated numbers Re. For supercritical numbers Re> Re _cr, we have C _Σ <C ₂ (decrease in C _Σ ) also due to C ₁ , which limits the undesirable increase in the rotational speed of the wind wheel with increasing wind speed and even allows you to stabilize this frequency at an approximately constant level.

The final result of the action of the turbulators T ₁ and T ₂ depends on the wind speed and, therefore, on the Reynolds number, as well as on the angular position of the turbulators and their length, which may be different for T ₁ and T ₂ . In particular, increasing the length T ₁ improves the starting conditions and limits the rotational speed of the wind wheel at high wind speeds. On the contrary, an increase in the length of T ₂ contributes to an increase in the rotational speed of the wind wheel at high wind speeds, which can be dangerous.

Wind turbine works as follows. Under starting conditions, when there is no rotation of the cylinders and the wind wheel (ω _c = ω _k = 0, Fig. 7), the turbulators T ₁ and T ₂ affect the position of the flow separation points (through the mechanisms described above) and create an asymmetry around the cylinder: separation point 7 is located further downstream than point 8. There is a pressure difference on the upper and lower sides of the cylinder with the appearance of an aerodynamic force Y _t , which causes the wind wheel to rotate. The rotation of the wind wheel is transmitted through the multiplier to the generator, from which the generated energy is supplied to the electric cylinders. When the latter rotates, a Magnus force Y _m arises, the effect of which increases the rotational speed of the wind wheel and, accordingly, the generator speed, as a result of which the calculated mode of operation of the wind turbine is achieved, corresponding to the estimated wind speed and the installed power of the generator.

 When starting a wind wheel, the generator energy is used only to rotate the cylinders. After reaching the design mode, the power consumption for the rotation of the cylinders is only a small part of the total generator power. These costs decrease with decreasing length of the rotating part of the cylinders. In the absence of a non-rotating root part, the power consumption for rotation is up to 10 - 12%. When reducing the length of the rotating part of the cylinders due to the non-rotating part, these costs are reduced by at least 1.5 times. Moreover, with an increase in wind speed above the calculated value, the influence of turbulators increases, and the effect of cylinder rotation, on the contrary, decreases, which creates conditions for a further reduction in power consumption for cylinder rotation up to zero at sufficiently high wind speeds.

The growing influence of turbulators with increasing wind speed follows from the fact that the power of any wind turbine has the form
N = K • C _F • V ³ • S; S = d • L _T ,
Where
K is the coefficient of proportionality;
S is the area (in this case, S = d • L _t ;
C _F is the coefficient of the driving force of the wind wheel, which depends on the magnitude of the lifting force and resistance of the cylinder and is a function of the coefficients C ₁ and C ₂ discussed above (see Fig. 5, 6). From the formula it follows that the power is proportional to the cube of wind speed. Then, at constant values of K, C and S, an increase in wind speed, for example, by a factor of two will lead to an increase in power by 8 times, which may exceed the capabilities of rotating cylinders and, therefore, they will not be required to rotate, the wind wheel will work only due to turbulators.

On the other hand, the design mode of operation of the wind wheel is achieved at some optimal value of the relative speed of rotation of the cylinders
Q = ω _c d / 2V = 2-3,
whence it is seen that with increasing wind speed, but at a constant cylinder speed ω _c = const, the value of Q decreases. This means a decrease in the contribution of rotating cylinders to the total power of the wind wheel, and, therefore, the power consumption for rotating the cylinders can be reduced in comparison with the conditions in the design mode, at which these costs were maximum.

In FIG. Figure 8 shows the pattern of flow around the cylinder in the design mode. The rotation of the wind wheel is carried out under the action of a driving force F <Y _Σ = Y _t + Y _m , with the braking effect of the resistance force of the cylinders (not shown in the diagram). When the wind wheel rotates, a circumferential component of the flow velocity appears, and as a result, the total flow flowing around each cylinder with the total speed V _Σ rotates from the initial direction (from the velocity vector V) by the angle φ _Σ . The most optimal condition in this case is the equality of the angles φ _Σ = φ ₁ (shown in Fig. 8). In this case, the turbulator T ₁ does not create a driving force, but reduces the resistance of the cylinder, which increases the efficiency of the wind wheel. The turbulator T ₂ at some part of its length is in this case in the aerodynamic shadow, i.e. behind the separation point 8, where it enters, starting from the end sections, where the peripheral speed is higher, therefore, the angle φ _{Σ is} larger than in the root sections. The change in the pattern of flow around the cylinders associated with the rotation of the flow creates the conditions for self-regulation of the operation of the wind wheel using turbulators T ₁ and T ₂ .

на фиг. 3 и 4. При увеличении частоты вращения ветроколеса будет угол Δφ₁<0, сила ΔY₁<0, и наоборот, что способствует восстановлению исходного (расчетного) режима работы. Турбулизатор T₂ в отличие от T₁ осуществляет при этом саморегулирование за счет изменения длины активной части турбулизатора, находящейся вне аэродинамической тени. С увеличением частоты вращения ветроколеса, т.е. при Δφ₁<0, длина активной части турбулизатора T₂ уменьшается, сила Y₂ тоже уменьшается, и наоборот, что способствует восстановлению исходного режима работы.Self-regulation of the wind wheel is as follows. When deviating from the design mode, i.e. when increasing or, conversely, decreasing the frequency of rotation of the wind wheel from the calculated value, the angle corresponding to the direction of the velocity V _{Σ of the} total flow incident on the cylinder accordingly changes (see Fig. 8). This means that the initial, optimal condition φ _Σ = φ _{1 is} violated, there is a mismatch angle Δφ ₁ = φ ₁ -φ _Σ ≠ 0.
In the presence of a mismatch angle under the action of the turbulator T ₁ , a restoring force ΔY ₁ (Δφ ₁ ) appears, the value and sign of which change in accordance with the coefficient behavior graph

in FIG. 3 and 4. With an increase in the rotational speed of the wind wheel there will be an angle Δφ ₁ <0, a force ΔY ₁ <0, and vice versa, which helps to restore the original (calculated) operating mode. The turbulator T _2, in contrast to T _1, performs self-regulation by changing the length of the active part of the turbulator outside the aerodynamic shadow. With increasing speed of the wind wheel, i.e. when Δφ ₁ <0, the length of the active part of the turbulator T ₂ decreases, the force Y ₂ also decreases, and vice versa, which helps to restore the original mode of operation.

In FIG. 9 according to the results of tests in the ITPM wind tunnel with the number Re = 0.7 • 10 ⁵ , the rotational speed of the wind wheel n _k is shown depending on the value of the relative cylinder speed Q = ω _c d / 2V in the presence of turbulators (curve 9) and without them ( curve 10). It can be seen that the turbulators provide self-starting of the wind wheel (n _k > 0 at Q = 0), as well as an increase in n _k with increasing Q in the region Q <1, i.e. we have an improvement in the performance of the wind wheel compared to the version without turbulators. At Q <0.5, a wind wheel without turbulators cannot be started, and with turbulators it rotates with a frequency sufficient for the initial operation of the electric generator, providing power to the electric drives for rotating the cylinders. The rotation of the cylinders, as already noted, contributes to a further increase in the frequency of rotation of the wind wheel and the achievement of the calculated mode of operation with self-regulation due to the turbulators T ₁ and T ₂ . If necessary, additional regulation is carried out by changing the frequency of rotation of the cylinders, which is most effective with the estimated wind speed and deviations from it up to 50%. With an increase of more than two times the wind speed, the regulation of the cylinder speed will be ineffective, as can be seen from the graph in FIG. nine.

Thus, the regulatory effect of the turbulators T ₁ and T ₂ depends on the deviation of the actual speed of rotation of the wind wheel from the calculated value, which is expressed by the mismatch angle Δφ ₁ . The latter, in turn, depends on a number of parameters: the length of the turbulators and the angle of their installation, wind speed and Reynolds number, cylinder speed. By choosing the length of the turbulizers and the angle of their installation, the most optimal conditions are provided both for the self-starting of the wind wheel and for its safe operation at elevated and stormy wind speeds. To this end, at the initial stage of operation, it is advisable to reduce the length of the turbulator T ₂ to a minimum that allows the wind wheel to self-start together with the turbulator T ₁ and at the same time limit its rotation frequency to a safe level at high wind speeds. It is necessary to be able to subsequently increase the length of the turbulator T ₂ if, with increasing wind speed, the rotational speed of the wind wheel drops below the required values, as is the case for a wind wheel without turbulators, as can be seen from the graph in FIG. nine.

The angles of installation of the turbulators mentioned above, φ ₁ = 45 ^o , φ ₂ = -90 ^o , (see paragraph 1 of the claims), are optimal for self-start of the wind wheel, but not optimal for self-regulation of its operation, because there are restrictions on the circumferential speed of rotation of the cylinders and the wind wheel, as well as on the Reynolds number.

где R - радиус ветроколеса, r - расстояние от оси ветроколеса, k = 0,5 - 0,8 - коэффициент, зависящий от конструкции ветроустановки и режима работы, причем k < 0,6 при числах Re < Re_кр и k > 0,6 при числах Re > Re_кр. На вращающейся части цилиндров угол φ₁ не должен превышать 45^o.To simultaneously fulfill these conditions, the turbulators are set as follows (see paragraph 2 of the claims)

where R is the radius of the wind wheel, r is the distance from the axis of the wind wheel, k = 0.5 - 0.8 is a coefficient depending on the design of the wind turbine and the operating mode, and k <0.6 for the numbers Re <Re _cr and k> 0, 6 for numbers Re> Re _cr . On the rotating part of the cylinders, the angle φ ₁ should not exceed 45 ^o .

 The minimum wind speed at which the wind wheel starts to rotate with cylinders (powered by a battery or other external energy source) is about 1 m / s. The wind speed at which the wind wheel self-starts under the action of turbulators without preliminary cylinder rotation (fully autonomous operation) is about 3 m / s. The operating range of wind speeds for a wind wheel with rotating cylinders and with turbulators is from 2 to 40 m / s, which significantly exceeds the same indicator for traditional paddle wind turbines.

Claims (3)

1. A wind turbine containing a wind wheel with a horizontal axis of rotation and radially mounted cylinders with end washers and longitudinal turbulators, as well as a cylinder drive and an electric generator, characterized in that the cylinders are made up of rotating end and non-rotating root parts and are equipped with two turbulators in the form of tubes, located along cylinders with angular coordinates relative to the wind direction φ ₁ = 45 ^° , φ ₂ = -90 ^° and gaps h ₁ = (0.1-0.2) d, 0 <h ₂ <0.05 d, and the diameter of the tubes is d _t = (0,1-0,2) d, their length L and _{n m} = L + aL _in, where d - diameter of the cylinder; h ₁ , h ₂ - the distance from the surface of the cylinder to the corresponding turbulator; L _n - the length of the non-rotating part of the cylinder; L _in - the length of the rotating part of the cylinder; a = 0.2 - 0.8 is a coefficient depending on the design of the installation and the operating mode. 2. A wind turbine containing a wind wheel with a horizontal axis of rotation and radially mounted cylinders with end washers and longitudinal turbulators, as well as a cylinder drive and an electric generator, characterized in that the cylinders are made up of rotating end and non-rotating root parts and are equipped with two turbulators in the form of tubes, installed in a spiral around the axis of the cylinders with angular coordinates relative to the direction of the wind

where r is the distance from the axis of the wind wheel;
R is the radius of the wind wheel;
k = 0.5-0.8 - coefficient depending on the design of the wind turbine and the operating mode,
and the gaps h ₁ = (0,1-0,2) d, 0 <h ₂ <0,05d, and the diameter of the tubes is d _t = (0,1-0,2) d, their length L _t = L _n + aL _in , where d is the cylinder diameter; h ₁ h ₂ is the distance from the surface of the cylinder to the corresponding turbulator; L _n - the length of the non-rotating part of the cylinder; L _in - the length of the rotating part; a = 0.2 - 0.8 is a coefficient depending on the design of the installation and the operating mode.  3. The method of operation of a wind turbine, including starting a wind wheel, generating energy and regulating it, characterized in that the wind wheel is self-starting due to the aerodynamic force created by the turbulators on the surface of the cylinders, the received energy is partially transferred to the drive of the moving parts of the cylinders until the normal operating mode of the installation and keep this mode constant due to the compensating forces of the turbulators and additional regulation of the cylinder speed from nominal to zero.

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