阅读说明：本技术 叶片、风力发电机组及其操作方法 (Blade, wind generating set and operation method thereof ) 是由 肖智龙 陈威 闻笔荣 于 2020-05-29 设计创作，主要内容包括：本发明实施例提供一种叶片、风力发电机组及其操作方法。叶片包括吸力面壳体和压力面壳体,叶片还包括布置在吸力面壳体上的离散的多个吸气孔,离散的多个吸气孔位于叶片的主梁和叶片的后缘之间。该用于风力发电机组的叶片可以有效抑制叶片吸力面气动转捩(气流分离),扩大叶片吸力面层流流动区域,解决叶片运行失速问题,从而提升机组发电量；确保发电量的同时,不会给机组带来气动噪声。(The embodiment of the invention provides a blade, a wind generating set and an operation method of the wind generating set. The blade includes a suction side shell and a pressure side shell, the blade further including a discrete plurality of suction holes disposed on the suction side shell, the discrete plurality of suction holes being located between a leading edge of the blade and a trailing edge of the blade. The blade for the wind generating set can effectively inhibit aerodynamic transition (airflow separation) of the suction surface of the blade, expand the laminar flow area of the suction surface of the blade and solve the problem of operation stall of the blade, so that the generating capacity of the wind generating set is improved; and pneumatic noise cannot be brought to the unit while the generated energy is ensured.)

1. A blade for a wind power plant, said blade (1) comprising a suction side shell and a pressure side shell, characterized in that said blade (1) further comprises a discrete number of suction apertures (13) arranged on said suction side shell, said discrete number of suction apertures (13) being located between a main beam (11) of said blade (1) and a trailing edge (6) of said blade (1).

2. Blade according to claim 1, wherein the discrete plurality of suction holes (13) has a hole pitch to hole diameter ratio of 8-12.

3. Blade according to claim 1, characterized in that the discrete plurality of suction holes (13) are distributed from the root pitch circle end position to 20-30% of the spanwise direction of the blade (1).

4. Blade according to claim 1, characterized in that the discrete plurality of suction holes (13) are at a distance from the edge of the monoaxial distribution area of the main beam (11) and the edge of the monoaxial distribution area (12) of the trailing edge (6).

5. The blade of claim 4, wherein said distance is 10-15 cm.

6. Blade according to claim 1, wherein in the area of the suction aperture where the discrete number of suction apertures (13) are distributed, the outer surface of the suction surface shell is provided with a semi-permeable membrane (23) to cover the discrete number of suction apertures (13).

7. Blade according to claim 6, characterized in that the blade (1) further comprises:

a sealed chamber (22) located in the area of the suction aperture, arranged on the inner surface of the suction face casing to cover the discrete plurality of suction apertures (13), and forming a gas containment chamber at the outlet of the discrete plurality of suction apertures (13);

the first end of the air exhaust pipe (21) is connected with the sealed cabin (22);

the air pump (24) is connected with the second end of the air exhaust pipe (21);

the first end of the air guide pipe (15) is connected with an air outlet of the air pump (24);

a controller for opening the sealed chamber (22) and controlling the air pump (24) to draw air from the outer surface of the suction surface housing through the discrete plurality of air draw holes (13).

8. A blade according to claim 7, characterised in that the second end of the air duct (15) communicates with at least one of the blade tip exhaust holes (14) and the blade root exhaust holes of the blade (1).

9. Blade according to claim 7, characterized in that the air pump (24) is fixed at the angle between the trailing edge web and the inner surface of the suction side shell and on the side of the suction hole area close to the blade tip (4).

10. A blade according to claim 9, characterised in that the second end of the extraction duct (21) and the air duct (15) are fixed at the angle between the trailing edge web and the inner surface of the suction surface shell.

11. The blade according to claim 7, wherein the suction hole area is divided into a plurality of sub-areas, the capsule (22) comprising a plurality of sub-capsules communicating with the suction holes in the plurality of sub-areas, respectively, the plurality of sub-capsules being controllable by the controller, respectively.

12. A blade according to claim 11, characterised in that the suction hole area is divided into a plurality of sub-areas in the chordwise direction of the blade (1), which sub-areas each extend in the spanwise direction of the blade (1).

13. A method of operating a blade according to claim 11, comprising:

-when the blade (1) is in the non-stalled condition, the controller controls the sealed capsule (22) to close the discrete plurality of suction holes (13);

when the blade (1) is in a stall condition, the controller controls at least one of the sub-pods to open, controlling the air pump (24) to draw air through the discrete plurality of suction holes (13).

14. A wind park comprising a blade according to any of claims 1-12.

Technical Field

The invention relates to the technical field of wind power generation, in particular to a blade, a wind generating set and an operation method of the wind generating set.

Background

A wind generator is an aerodynamic device that relies on the lift of the blade airfoil to operate. The upper surface (suction surface) of the airfoil is dominated by a large positive pressure gradient, and therefore flow separation or stall easily occurs at large angles of attack; the lower surface (pressure surface) of the airfoil is a negative pressure gradient in the first half and a smaller positive pressure gradient in the second half, so that flow separation does not typically occur. Microscopically, "stall" is the loss of forward velocity of the airflow near the blade wall. Macroscopically or from the integral components of the lift coefficient and the drag coefficient of the airfoil, the lift increases linearly with the increase of the attack angle, but after a certain critical value is reached, the lift suddenly decreases, the drag is greatly increased, and the stall occurs. Macroscopically, the "stall" is lost not "speed" and the "lift" is lost.

Because the wind turbine works in the atmospheric boundary layer with violent wind speed change, the control system cannot timely intervene to cause the blades to temporarily work under stall probably due to sudden change of wind speed and wind direction. If the fan blade, especially the outer side of the blade, is operated in a stall state for a long time, although the load does not exceed the limit load, the high-frequency alternating load can be generated due to flow separation, which affects the fatigue life of the blade and the unit, and meanwhile, the power generation performance can be greatly reduced due to the extremely low lift-drag ratio of the airfoil profile under the stall. It is therefore necessary to avoid operating the wind turbine in a stall condition for a long time.

Disclosure of Invention

The invention aims to provide a blade, a wind generating set and an operation method thereof, which aim to solve the problem of operating stall of the blade.

In a first aspect, the present invention provides a blade for a wind power plant, the blade comprising a suction side shell and a pressure side shell, the blade further comprising a discrete plurality of suction holes arranged on the suction side shell, the discrete plurality of suction holes being located between a main beam of the blade and a trailing edge of the blade.

Optionally, the discrete plurality of suction holes have a hole pitch to hole diameter ratio of 8-12.

Optionally, the discrete plurality of suction holes are distributed from a root pitch circle end position to 20% to 30% of a spanwise direction of the blade.

Optionally, the discrete plurality of suction holes are spaced a distance from an edge of the monoaxial fabric region of the leading edge and an edge of the monoaxial fabric region of the trailing edge.

Optionally, the distance is 10-15 cm.

Optionally, in the area of the suction hole distributed by the discrete plurality of suction holes, the outer surface of the suction surface casing is provided with a semi-permeable membrane to cover the discrete plurality of suction holes.

Optionally, the blade further comprises: a sealed chamber located in the area of the suction hole, arranged on the inner surface of the suction surface shell to cover the discrete suction holes and forming a gas containing cavity at the outlet of the discrete suction holes; the first end of the exhaust pipe is connected with the sealed cabin; the air pump is connected with the second end of the air exhaust pipe; the first end of the air guide pipe is connected with an air outlet of the air pump; a controller for opening the sealed chamber and controlling the air pump to draw air from the outer surface of the suction surface housing through the discrete plurality of air draw holes.

Optionally, the second end of the air duct is communicated with at least one of the blade tip exhaust hole and the blade root exhaust hole of the blade.

Optionally, the air pump is fixed at an included angle between the trailing edge web and the inner surface of the suction surface shell and is positioned on one side of the suction hole area close to the blade tip.

Optionally, the second end of the exhaust tube and the air duct are fixed at an included angle between the trailing edge web and the inner surface of the suction surface shell.

Optionally, the suction hole area is divided into a plurality of sub-areas, and the capsule includes a plurality of sub-capsules respectively communicating with the suction holes in the plurality of sub-areas, the plurality of sub-capsules being respectively controllable by the controller.

Optionally, the suction hole region is divided into a plurality of sub-regions in a chordwise direction of the blade, and the plurality of sub-regions extend in a spanwise direction of the blade, respectively.

In a second aspect, the present invention provides a method of operating a blade as described above, the method comprising: when the blade is in an stalled condition, the controller controls the capsule to close the discrete plurality of suction holes; when the blade is in a stall state, the controller controls at least one of the sub-pods to open and controls the air pump to draw air through the discrete plurality of air suction holes.

In a third aspect, the invention provides a wind turbine comprising a blade according to any of the preceding claims.

According to the blade, the wind generating set and the operation method thereof provided by the embodiment of the invention, the following beneficial technical effects are achieved: the aerodynamic transition (airflow separation) of the suction surface of the blade is effectively inhibited, the laminar flow area of the suction surface of the blade is expanded, the problem of operation stall of the blade is solved, and therefore the generating capacity of a unit is improved; and pneumatic noise cannot be brought to the unit while the generated energy is ensured.

Drawings

FIG. 1 is a schematic structural view of a blade according to an embodiment of the invention;

FIG. 2 is a graph comparing airflow characteristics across the surface of an actively aspirated front and rear blade according to an embodiment of the present invention;

FIG. 3 is a schematic illustration of component positions of a blade according to an embodiment of the invention;

FIG. 4 is a partially exploded schematic view of a blade according to an embodiment of the invention.

The reference numbers illustrate:

1-blade, 11-girder, 12-trailing edge uniaxial cloth area, 13-suction hole, 131-first suction area, 132-second suction area, 14-tip exhaust hole, 15-gas guide tube, 21-suction tube, 22-sealed cabin, 23-semipermeable membrane, 24-gas pump, 25-power distribution module, 26-cable, 220-first sealed cabin, 221-second sealed cabin, 3-blade root, 4-blade tip, 5-leading edge, 6-trailing edge, A-airflow separation point, B-vortex (turbulent flow)

Detailed Description

The current stall control modes are mainly of two categories: 1) an active stall control mode based on a particular control strategy; 2) and installing a Vortex Generator (VG) and other pneumatic accessory control modes. The optimization control strategy is an important means for avoiding stall, and the local attack angle of each spanwise section of the blade is mainly reduced through blade pitch control, so that the stall is further kept away, but the airfoil lift force is also lost, and the power generation loss is caused; vortex Generators (VGs) are widely used aerodynamic accessories, and the near-wall velocity blending is homogenized by the VGs to increase the stall critical angle of attack by increasing the maximum lift and delaying stall, but they also increase the drag by 10% to 30%, and if VGs are applied to the blade tip, they also bring additional noise sources.

According to the invention, the plurality of discrete air suction holes are distributed on the blade of the wind generating set, and an active air suction method is adopted to induce the laminar boundary layer flow field and improve the capability of the laminar boundary layer to resist the adverse pressure gradient, so that the air flow separation is inhibited, the laminar area on the surface of the blade is enlarged, and the problem of the stalling of the blade during operation is finally solved.

FIG. 1 is a schematic structural view of a blade according to an embodiment of the invention; FIG. 2 is a graph comparing airflow characteristics across the surface of an actively aspirated front and rear blade according to an embodiment of the present invention; FIG. 3 is a schematic illustration of component positions of a blade according to an embodiment of the invention; FIG. 4 is a partially exploded schematic view of a blade according to an embodiment of the invention.

As shown in fig. 1 to 2, a blade 1 according to an embodiment of the present invention includes a suction surface (SS surface) casing on which a plurality of discrete suction holes 13 are laid, and a pressure surface (PS surface) casing.

As shown in FIG. 2, the SS surface of the blade tends to stall because the SS surface is dominated by a large positive pressure gradient, and the PS surface is dominated by a negative pressure gradient in the first half and by a small positive pressure gradient in the second half, and generally does not stall. In the blade chord direction, after the inflow wind flows from the blade leading edge 5 to the position of the main beam 11 (shown in fig. 3) of the SS surface of the blade 1, the airflow separation a begins to occur, forming a vortex (turbulence) B, and continuing to the blade trailing edge 6, namely, a main stall area is formed between the position of the main beam and the trailing edge 6 of the blade 1; whereas in the blade span direction, the region where blade stall is typically severe is from the root pitch end position to 20% to 30% of the span direction of the blade 1.

Thus, preferably a discrete number of suction holes may be arranged in areas where stall is severe, said discrete number of suction holes 13 being located between the spar 11 of the blade 1 and the trailing edge 6 of the blade 1 in the blade chord direction, as shown in fig. 1.

The blade 1 is connected with a variable pitch bearing arranged on a hub of the wind generating set through a blade root. For interfacing with the pitch bearing, the blade root pitch circle segment is typically circular. The blade root pitch circle section mainly bears blade shearing force, bending moment and torque, and then is transmitted to the hub through the blade root 3 through the variable pitch bearing. Because the linear velocity of the area near the blade root 3 is lower, the aerodynamic load is also smaller, the influence on the blade and the unit is also smaller, and the safety is not damaged, discrete suction holes are not distributed on the blade root pitch circle segment, but distributed in the stall area of the blade from the end position of the blade root pitch circle segment. Preferably, said discrete plurality of suction holes 13 is distributed in the blade span direction from the root pitch circle end position to 20% to 30% of the span direction of the blade 1.

Since the stall regions of the blades of different airfoils differ, a discrete plurality of suction holes 13 may be arranged in all stall regions, depending on the blade. For example, if there is a stall phenomenon in the lobe region, a discrete plurality of suction holes 13 are provided in the lobe region, and thus, in the blade span direction, the discrete plurality of suction holes 13 may be provided from the root pitch circle end position to 20% to 40%, 20% to 45%, 20% to 50% of the span direction of the blade 1, but not limited thereto.

The single-shaft distribution area (UD area) of the main beam 11 is a main bearing component of the blade structure, so that the blade 1 can bear bending moment in the flapping direction and rigidity in the flapping direction; UD region 12 of trailing edge 6 is subjected to bending moments in the shimmy direction. These two regions are critical components of the blade and so preferably no holes are made in this region. Thus, as shown in FIG. 1, the discrete plurality of suction holes 13 are located at a distance from the edges of the uni-axial distribution area of the main beam 11 and the edges of the uni-axial distribution area of the trailing edge 6, which may be determined according to the blades of different airfoils, for example, but not limited thereto, the distance may be 10-15cm, 10-20cm, 10-25 cm.

As shown in fig. 1, the discrete plurality of suction holes 13 are discretely arranged in the region between the main beam 11 of the blade 1 and the trailing edge 6 of the blade 1, for example, in rows along the spanwise direction of the blade, in columns along the chordwise direction of the blade, for example, two rows of suction holes 13, which are adjacent in the chord direction, may be arranged to be staggered with respect to each other, such that one of the suction holes 13 of the second row is located between two adjacent suction holes 13 of the first row, for example at the midpoint of two adjacent suction holes 13 of the first row, so that these suction holes 13 do not form mutually-influenced vortices between the airflows generated upon suction, without being limited thereto, the discrete plurality of suction holes 13 may be arranged in other patterns, for example, in a plurality of concentric circular patterns, a plurality of elliptical patterns, as long as adjacent suction holes do not form mutually-influencing vortices between the airflows generated upon suction.

The suction speed can be effectively reduced by arranging a plurality of discrete suction holes on the wall surface of the blade for suction, so that the type selection capacity of the air suction pump is reduced. Meanwhile, the eddy interference among the air suction holes is reduced, and the laminar flow stability is improved. The air suction holes 13 are shown as circular holes in fig. 1, but the shape of the holes 13 may be rectangular, square or diamond. When the air suction holes 13 are circular holes, the ratio (namely L/d) of the distance L (hole distance) between adjacent holes to the diameter d (hole diameter) of the holes is 8-12, and the optimal value is 10, so that the adverse effect of the stability of a tropospheric boundary layer caused by air suction is reduced.

FIG. 4 shows a partially exploded schematic view of a blade according to an embodiment of the invention. As shown in fig. 4, the blade 1 may further include a semi-permeable membrane 23, a sealed cabin 22, an air pump 24, an air exhaust tube 21, an air duct 15, and a blade tip exhaust hole 14. The semi-permeable membrane 23 is a membrane that selectively permeates substances, and generally allows only a solvent or a solvent and a small molecular solute to permeate but not a large molecular solute to permeate. The semi-permeable membrane 23 covers the area of the blade suction hole 13 and is firmly bonded with the outer surface of the blade, so that air can freely pass through the suction hole 13, but impurities (such as particles of dust and the like) mixed with the air cannot pass through the semi-permeable membrane, the blockage of the suction hole 13 caused by the impurities is avoided, the active suction effect cannot be achieved, the smoothness of the surface of the blade is ensured, and the pneumatic noise source caused by the suction hole is avoided.

The sealed cabin 22 is arranged in the area of the suction hole distributed by the plurality of discrete suction holes 13, is firmly adhered to the inner surface of the suction surface shell of the blade to cover the suction holes 13, and forms a gas containing cavity at the outlet of the plurality of suction holes. The capsule 22 may be made of metal (alloy) or glass fiber reinforced plastic, and may be fixed on the blade inner cavity by hand pasting (bag pressing) or vacuum infusion process, and the capsule 22 may be opened and closed by a controller to open and close the suction holes 13.

The first end of the air pumping pipe 21 is connected with the sealed cabin 22, and the second end is connected with the air pumping port of the air pump 24. The air pump 24 may be a micro air pump (micro air pump) that draws air from one container to another container or directly to the atmosphere, and is called a "micro air pump" because of its small size and light weight.

The first end of the air duct 15 is connected with the exhaust port of the air pump 24, the air duct 15 is laid to the blade tip exhaust hole 14 along the blade span direction, and air is pushed to the position near the blade tip exhaust hole 14 through the air pumping and exhausting functions of the air pump 24. During the high speed rotation of the blade 1, centrifugal force is generated to discharge the air collected near the tip exhaust hole 14. The tip vents 14 may be arranged individually or may share the tip drain holes 14. According to embodiments of the present invention, the air discharged from the air pump 24 may be discharged through the tip discharge holes 14, through the root discharge holes, or through both the tip discharge holes 14 and the root discharge holes. That is, the second end of the air duct 15 may communicate with at least one of the tip exhaust hole 14 and the root exhaust hole of the blade. When exhausting from the blade root exhaust holes, the exhausted air may be used as a medium for air cooling heat dissipation from the nacelle or hub interior components. Of course, it is also possible to exhaust directly from the blade root hub into the atmosphere.

In addition, a power distribution module 25 and associated cables 26 and a controller (not shown) may also be provided. The air pump 24, the air suction pipe 21 and the air guide pipe 15 can be arranged in the blade inner cavity. A power distribution module 25 may be provided in the interior cavity of the blade to supply power to the air pump 24 through the power distribution module. Adopt discrete suction hole, can effectively reduce the speed of breathing in to reduce the electric load of air pump 24, consequently can be directly from setting up the switch board electricity that draws in the cabin. Further, in the case where the air pump is supplied with electric power by using a power distribution cabinet provided in the nacelle, the power distribution module 25 may be omitted. At this time, the air pump 24 may be connected to the power distribution cabinet through the mating cable 26. If the load of the power distribution cabinet is too large, the power distribution module 25 can be independently arranged to provide power.

Fig. 3 and 4 show the installation positions of the air pump 24, the air suction pipe 21 and the air guide pipe 15. In the working state, the blades are rotors rotating at high speed, so the fixation of the air pump 24, the air exhaust tube 21 and the air guide tube 15 is particularly important. The air pump 24 may be fixed at the included angle between the trailing edge web and the inner surface of the SS panel casing in the chord direction, may be arranged on the side of the suction hole 13 area close to the blade tip in the span direction to reduce the path length of the air duct 15, and may be bonded to the blade cavity and the web by means of a frp hand lay-up bracket. In addition, because the second end of the exhaust tube 21 and the air duct 15 are connected with the air pump 24, the air duct 15 and the exhaust tube 21 are also fixed at the included angle between the rear edge web and the inner surface of the SS face shell and are pressed and bonded on the SS face shell and the rear edge web through the glass fiber reinforced plastic hand pasting bag.

As described above, in the process of manufacturing the blade, the air duct 15 may be laid to the tip exhaust hole 14 at the same time so that it is formed at the same time as the blade, and other components (such as the semipermeable membrane 23, the capsule 22, the air pump 24, the air suction pipe 21, and the mating cable 26) may be formed at the same time as the blade or may be separately arranged after the blade is manufactured.

As described above, the semi-permeable membrane 23, the air intake hole 13, the sealed cabin 22, the air pump 24, the air exhaust tube 21, the air duct 15, the blade tip exhaust hole 14, the power distribution module 25, the matching cable 26 and the controller form a blade active air intake system, and the sealed cabin 22, the air intake hole 13 and the semi-permeable membrane 23 form a sealed system. Taking fig. 1 and 3 as an example, in the non-stall state of the blade (the active air suction system is not in operation), the controller controls the sealed cabin 22 to be in a closed state to close the air suction hole 13, the whole sealed system is in a sealed state, and air cannot enter the blade through the semi-permeable membrane 23, so that no aerodynamic noise source is brought to the blade; when the stall occurs on the suction surface of the blade in the operation process of the wind generating set, the controller controls the sealed cabin 22 to be opened, the air suction hole 13 is opened at the moment, the controller controls the air pump 24 to suck air through the air suction hole 13, at the moment, the air penetrates through the semipermeable membrane 23 from the outside to enter the blade, and through the control technology of active air suction of the blade, the occurrence of aerodynamic transition and airflow separation can be effectively inhibited, the laminar flow area on the surface of the blade SS is enlarged, the resistance of a turbulent flow boundary layer is reduced, the problem of the stall during operation of the blade is solved, and finally the loss of the generated energy of the set is reduced.

Furthermore, the active suction of the blade 1 can be controlled in sections, i.e. the suction hole area is divided into a plurality of sub-areas. Preferably, the suction hole area is divided into a plurality of sub-areas in a chord direction of the blade, such that the plurality of sub-areas extend in a span-wise direction of the blade, respectively. Accordingly, the capsule 22 includes a plurality of sub capsules respectively communicating with the suction holes 13 in the plurality of sub areas, and the controller respectively controls the operation of the plurality of sub capsules. As an example, fig. 1 shows that the suction hole area is divided into a first suction area 131 and a second suction area 132, and correspondingly, as shown in fig. 3, the hermetic chamber 22 includes a first hermetic chamber 220 and a second hermetic chamber 221 which communicate with the suction holes 13 in the first suction area 131 and the second suction area 132, respectively. As shown, the first capsule 220 is disposed adjacent to the laminar boundary layer region and functions as a primary and the second capsule 221 functions as a secondary. But not limited thereto, the area of the air suction hole 13 may be divided into more than two sub-areas, for example, 3, 4, and correspondingly, the capsule 22 includes more than two sub-capsules according to the requirement. According to the actual condition of the partition control, the air exhaust pipe 21 adopts a one-driving-multiple type air exhaust pipe which is respectively connected with each sealed cabin, and each sub air exhaust pipe can independently control the opening and closing of the air exhaust action through a valve.

As described above, when the blade is in the stall state, the controller controls the first sealed cabin 220 of the sealed cabin 22 to open, at this time, the air suction hole 13 is opened, the controller controls the air pump 24 to suck air through the air suction hole 13, at this time, air enters the blade from the outside through the semipermeable membrane 23, the process induces a laminar boundary layer flow field in the area of the air suction hole 13, delays the transition of the boundary layer, and forms a stable boundary layer, at this time, if the trailing edge of the SS surface of the blade still has a turbulent flow, the second sealed cabin 221 is opened again (by analogy, in the case that more than two sealed sub-cabins are provided, more sealed sub-cabins are opened again). Through the zone control, the stall conditions of different degrees in the running process of the unit can be controlled respectively, the control strategy is optimized, and the power is saved.

The advantages of the above technical scheme include: the aerodynamic transition (airflow separation) of the suction surface of the blade is effectively inhibited, the laminar flow area of the suction surface of the blade is expanded, the problem of operation stall of the blade is solved, and therefore the generating capacity of a unit is improved; and pneumatic noise cannot be brought to the unit while the generated energy is ensured.

The above description is only for the specific embodiments of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art can easily conceive of the changes or substitutions within the technical scope of the present invention, and all the changes or substitutions should be covered within the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the appended claims.