RU2536442C2 - Air propeller of wind-driven power plants with adaptive blades - Google Patents

Abstract

FIELD: power industry.

SUBSTANCE: invention relates to wind-driven power plants, and namely to a structure of rotors of wind-driven power plants with a horizontal shaft. An air propeller consists of a hub, two connection plates and three pipes clamped between them by bolts for connection of root sections of blades. Each of the blades consists of a tubular spar and ribs (root, type and end ones) put on it in a movable manner. An end rib is connected to an end of a torsion passing inside the end part of the tubular spar. An opposite end of the torsion is attached to the tubular spar. All the sections, except for the root one, have an outline that is open along the rear edge. This contributes to low torsional stiffness of an adaptive blade. The root section has an aerodynamic flap representing a profile with an increased chord. A load of a centrifugal control is attached to the root rib. Torques created with the load of the centrifugal control and the aerodynamic profile, as well as with the closed outline of the root section are transmitted to the open outline of the blade throughout its length.

EFFECT: invention allows improving use coefficient of energy of abrupt wind gusts due to automatic elimination of stalling zones on propeller blades.

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Description

The invention relates to wind power plants, and in particular to the design of rotors of wind power plants with a horizontal shaft.

The invention can also be used on propellers of aircraft with a wide range of propeller treads operating in unsteady turbulent flows, for example, aircraft with vertical launch.

Known propellers of wind power plants with a fixed pitch and blades without geometric twist. The advantage of such screws is the simplicity of design and manufacturing technology. These screws have two significant drawbacks. The first of them is that only a small part of the blade works at the angles of attack, providing optimal flow around. When designing, developers strive to ensure that this region is at a radius of r = 0.75K (where K is the radius of the rotor of the screw). However, with a change in the flow velocity, this section shifts along the axis of the blade in one or the other direction. There are sections of the blade with stall flow, that is, sections whose profile angles of attack are higher than critical. This operation of the blade and propeller may be accompanied by vibration and noise. The coefficient of use of wind energy (KIEV) of such screws usually does not exceed 20-25%. The second disadvantage is that with a change in wind speed, the rotational speed of the screw changes significantly. For these two reasons, such screws are used only in low-power wind turbines with automotive-type generators with various kinds of rotor speed limiters. [Wind turbines. Assessment of the energy potential of the wind. http: narod.ru/gratis/winds.htm].

Known propellers for fixed-pitch wind power plants and blades with geometric twist. The advantage of such screws is that at a certain flow rate, which was designed by the developer, all sections work at the optimum angle of attack, the KIEV of the screw in this mode can reach 40%, and the screw creates minimal noise. Along with the increasing complexity of blade manufacturing technology, the disadvantage of such a screw is still an insufficiently wide range of optimal flow around the flow rate. Depending on the wind speed KIEV of such screws can be in the range from 25 to 40%. These screws must also work with rotor speed limiters. [Larionova A.V., Chumak P.I. Progress in the design and manufacture of small-sized wind turbines. Russian civilization: past, present and future P76 // Collection of scientific papers of the III scientific and practical conference. - Stavropol: LLC “Data World”, 2010. p. 356-358].

Wind power propellers with variable pitch blades but without geometric twist are widely known. Such screws are still widely used. Their main advantage is a wide range of work in terms of wind speed, since the regulator adjusts the angles of attack so that the rotor speed is kept close to the specified value. In most cases, the regulator takes over the functions of the speed limiter.

The disadvantage of such propellers is that optimal flow is carried out in a small area of the blade, which to some extent affects both the value of KIEV (wind energy utilization factor) and their noise.

Also known are screws, the blades of which are connected to the shaft by means of torsion resilient bending and torsion (US patent No. 4427340, IPC ВСС 27/38). In such a screw, the zone closest to the blade, working mainly on torsion, consists of monolithic longitudinally located ribbed beams made in the form of elements of an open (open) profile.

The disadvantages of this design include the difficulty of obtaining optimal sizes of torsion bars, providing high bending stiffness with low torsional stiffness.

Known propeller with a variable pitch of the blades (RF patent for the invention No. 2349504, class B64C 27/48), connected to the shaft of the screw by means of elastic bending and torsion torsions made in areas experiencing predominantly torsional deformation in the form of a beam consisting of longitudinally located power elements of an open profile with high strength of the material, interconnected by an elastic filler, and in terminations at the ends of the torsion bar or torsion section - in the bend zone, at the junction of the torsion bar with a blade, shaft, and intermediate with the details, at the points of connection of the torsion and bending zones of one torsion or torsion with each other, the power elements are rigidly connected to each other by a material with high strength. Such a screw will work well with oblique blowing or with an uneven velocity field in front of the screw. The disadvantage of this screw, as discussed above, is that the regulator adjusts for optimal operation only a small section of the blade, usually near a radius r = 0.75K. The use of the geometric and aerodynamic twist of the rigid feather of the blade does not extend the range of the optimal zone to the entire blade.

Known propeller of a wind power installation with variable geometry blades (RF patent for the invention No. 2460901 C1, F03D 1/06), taken as a prototype, including blades connected to the screw shaft, control unit, torsion-resistant bending and torsion, having this is the aerodynamic profile of the blade that is not closed at the trailing edge, consisting of a sheathing and a set of reinforcing typical ribs, connected to the screw shaft with the help of an end rib, a torsion bar, a tubular shaft acting as a spar, and a butt of the blade, while the rigidity of the torso for torsion, it is selected from the condition of the maximum required rotation of the end rib at the maximum torque applied by the control unit, a centrifugal regulator, to the skin contour from the side of the root rib, and the stiffness of the open contour of the blade sheath is selected so that the root rib is also set to the optimal angle at the maximum given wind speed.

The disadvantage of the prototype is the lack of energy efficiency of sudden gusts of wind.

The technical problem solved by the claimed invention is to eliminate the disadvantage of the prototype and the design of the propeller, which allows the efficient use of the energy of sudden gusts of wind, carrying a sufficiently large share of its energy, especially at a low average flow rate, and previously not used by the propellers of existing wind power plants .

The technical result of the claimed invention is expressed in an increase in the coefficient of utilization of wind energy due to the automatic elimination of stall zones on the blades of the screw, due to the rapid change in the angle of installation of its sections with a large gradient of the flow velocity, by shifting the center of pressure of the root part of the blade feather in the direction of flow by increasing the chord of the profile when using a specially installed aerodynamic shield.

The technical result of the invention is achieved in that the propeller of a wind power installation with adaptive blades, including blades connected to the screw shaft by means of butt sections, and a control unit, while the blades contain tubular spars, torsion-elastic torsion bars, an aerodynamic profile that is not closed at the trailing edge , consisting of a sheathing and a set of reinforcing typical ribs, connected at one end with a root rib, and the other, through an end rib and a torsion bar with a tubular shaft acting as a and a torsion torsion stiffness selected from the condition of the maximum required rotation of the end rib at the maximum twisting moment applied by the control unit to the skin contour from the side of the root rib, and the stiffness of the open contour of the blade skin is chosen so that the root rib is also set to the optimal angle at the maximum specified wind speed, according to the invention, the screw pitch control unit is additionally equipped with an aerodynamic profile with an increased chord, representing amounts to the visor provides the offset point of application of the resultant aerodynamic force in the direction of flow.

In FIG. 1 shows a General view of the propeller of a wind power installation with adaptive blades and its nodes in the context: FIG. 2 - node shear element protection system from a hurricane; FIG. 3 - torsion mount; FIG. 4 - thrust bearing assembly; FIG. 5 - the node mounting the flap; FIG. 6 - the node of the root rib.

Description of the device.

The propeller of a wind turbine with adaptive blades of FIG. 1 consists of a hub 1, two connecting plates 2, and sandwiched between them by means of bolts of three pipes 3 for connecting butt sections of the blades. Each of the blades consists of a tubular spar 4, movably mounted on it by means of non-metallic bushings, ribs: root 5, type 7 and end 10. The end rib 10, through the flange 11 (Fig. 2) and the bolt 12, is connected to the end of the torsion bar 9, passing inside the end of the tubular spar 4. The opposite end of the torsion 9 (Fig. 3), by means of a bolt 13, is attached to the tubular spar 4. The contour of the lining of the blade in the form of separate sections is attached to the shelves of ribs by rivets. All sections except the root have a contour that is not open at the trailing edge. This ensures low torsional rigidity of the adaptive blade. Inertial forces, from sheathing and ribs, by means of thrust bearings (Figs. 4, 6), and bushings 15 are transmitted to the tubular spar 4. The root section has an aerodynamic shield 6 representing profile 6 with an enlarged chord ( Fig. 7). The function of the aerodynamic shield 6 can perform a flat plate. To the root rib 5 (Fig. 6), the load 14 of the centrifugal regulator is attached. The torques created by the closed aerodynamic profile of the root section 6 and the load 14 of the centrifugal regulator are summed and transmitted to the open circuit of the blade along its entire length. This moment is counteracted by the moment of the torsion bar mounted in the tubular spar of the end part of the blade. Thus, the sections of the blade are in a position determined by the algebraic sum of the three above points.

The operation of the propeller of a wind power installation with adaptive blades is as follows.

When the screw is idle and there is no wind, the screw has a geometric twist, which ensures optimal flow around all sections at the starting speed at the nominal rotational speed of the screw shaft.

As the wind speed increases, the aerodynamic shield begins to create a twisting moment on the blade contour, providing an increase in the pitch of the blade sections. The greatest increase in pitch will be observed near the aerodynamic shield 6. Increasing the pitch will reduce stall zones, that is, zones with supercritical flow, which occupy almost the entire area of the blades on the stopped screw. Reducing these zones improves flow conditions and, very importantly, significantly reduces the starting speed of the screw.

The adaptive blade captures the energy of sudden gusts of wind at flow velocities slightly higher than the starting one, which does not occur even on blades of variable geometry, not to mention ordinary blades. With each rush, the aerodynamic shield 6 instantly creates a torsional moment on the blades, eliminating, or at least decreasing the zones of supercritical flow. This gives a positive effect at low wind speeds, when the flow energy needs to be especially valued. In this case, increasing the pitch of the blade not only does not reduce the torque and revolutions on the shaft, but also increases them.

The smaller the axial moment of inertia of the sheathing of the blade together with the ribs relative to the axis of the blade, the more effectively it responds to gusts of wind, capturing their energy.

Starting from the calculated (nominal) wind speed, the pitch of the blade is controlled by a centrifugal regulator through the stop of the aerodynamic shield 6, providing continuous flow around the blades. The aerodynamic shield 6 comes into operation only with very sharp gusts of wind.

At wind speeds higher than the calculated (including hurricane) aerodynamic shield 6, responding to sudden gusts of wind and working in conjunction with a centrifugal speed controller, prevents a sharp spin of the screw from a gusty gusty wind.

Thus, the aerodynamic shield 6 installed in the root part of the blade of variable geometry, together with the torsion bar installed in the end part of the blade, gives a positive effect, since it significantly increases the utilization of wind energy in all modes of operation of the propeller.

Claims (1)

The propeller of a wind power installation with adaptive blades, which includes blades connected to the propeller shaft via butt sections and a control unit, the blades containing tubular spars, torsion-elastic torsion bars, an aerodynamic profile open at the trailing edge, consisting of a sheathing and a set of reinforcing typical a rib connected at one end with a root rib and at the other, via an end rib and a torsion bar, with a tubular shaft acting as a spar, the torsion stiffness of the torsion bar being selected and h conditions for the maximum required rotation of the end rib at the maximum torsional moment applied by the control unit to the skin contour from the side of the root rib, and the stiffness of the open contour of the blade sheathing is chosen such that the root rib is also set to the optimal angle at the maximum wind speed, characterized in that the screw pitch control unit is additionally equipped with an aerodynamic profile with an enlarged chord, which is a shield that provides an attachment point the resultant aerodynamic force in the direction of flow.

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