WO2022001691A1

WO2022001691A1 - Shark gill-shaped blade drag reduction structure for wind generator, blade, and manufacturing method

Info

Publication number: WO2022001691A1
Application number: PCT/CN2021/100836
Authority: WO
Inventors: 吴宛洋; 钟兢军
Original assignee: 上海海事大学
Priority date: 2020-06-28
Filing date: 2021-06-18
Publication date: 2022-01-06
Also published as: CN111577531A; DE112021003476T5; CN111577531B

Abstract

A shark gill-shaped blade drag reduction structure for a wind generator, a blade, and a manufacturing method. The blade drag reduction structure of the wind generator is disposed on the surface of a blade and comprises a slot provided on the blade. The slot is provided with an airflow inlet (2) and multiple airflow outlets. An airflow channel (8) is formed between the airflow inlet and the multiple airflow outlets. When the blade rotates, airflow enters from the airflow inlet and then passes through the airflow outlet along the airflow channel so as to form a jet flow. The flow rate of air in the airflow channel is lower than that of a main flow. The flow path of the jet flow flowing out from the airflow outlet is bent under the impact of the main flow, such that a buffer region is formed between the blade surface and the main flow, thereby reducing the friction of the main flow on the blade.

Description

Shark gill blade drag reduction structure for wind turbine, blade and manufacturing method

technical field

The invention relates to the technical field of wind power generation, in particular to a drag reduction structure of a shark gill-type blade for a wind power generator, a blade and a manufacturing method thereof.

Background technique

Wind is an extremely common natural phenomenon, and the wind energy derived from it is an inexhaustible and inexhaustible renewable resource. With the increasing demand for energy and the urgent requirement of energy transformation, wind power generation has developed rapidly and is currently the most mature way of wind energy utilization in the world. After the war, Danish engineers built small wind turbines based on the principles of aircraft propellers. The use of wind energy for power generation in China began in the 1970s. At that time, micro- and small-scale wind turbines were the main components. In the 1980s, medium and large-scale generators were developed.

The process of wind power generation means that the kinetic energy of the wind is converted into mechanical energy by wind turbines, and then converted into electrical energy after driving the generator to generate electricity. Wind turbine is the core component of wind power generation system. Wind turbine is mainly divided into vertical axis and horizontal axis. Horizontal axis wind turbine has higher wind energy utilization efficiency and wider application range. A typical horizontal axis wind turbine is mainly composed of a wind wheel, a nacelle, a hub, a governor, a steering device, a transmission mechanism, a mechanical brake device and a tower. The wind wheel of the horizontal axis fan is composed of blades with excellent aerodynamic performance (currently commercial units generally have 2 to 3 blades) mounted on the hub. The blades rotate around a horizontal axis, and the rotation plane is perpendicular to the wind direction. The low-speed rotating wind wheel is accelerated by the speed-increasing gearbox through the transmission system, and the power is transmitted to the generator. The wind turbine blade is an important core component of the wind turbine, and its performance directly affects the power generation efficiency. The resistance suffered by the blade during the rotation process mainly comes from the resistance of mutual friction between the blade and the surrounding airflow, which can even be as high as 70% of the total resistance, which greatly increases the energy consumption of the wind turbine. Therefore, reducing the resistance of the blade and improving the wind power The efficiency of the generator set is directly related.

In nature, when sharks breathe, water enters the pharynx from the mouth and the water inlet, and flows out of the body through the gill slits. The outer gill slits of sharks are approximately in the same plane as the surrounding body surface. The gill slits expel seawater outward and interact with the surrounding environmental fluid to change the structure of the flow field around the shark's body surface and reduce the resistance of the shark's body surface. The invention designs a new type of wind turbine blade drag reduction structure based on the bionic structure of the shark gill slit. The appearance of the wind turbine blade is streamlined, and the blade structure of the invention is set to adopt a shark gill slit structure on the windward side of the blade, with one (or more) inlets for air intake, multiple outlets for air outlet, and an air flow channel is formed between the inlet and outlet, and the outlet A jet flow phenomenon is formed at the cross section. The flowing airflow is viscous, and a boundary layer is formed near the wind turbine blades. There is a velocity gradient in the boundary layer. The magnitude of the frictional resistance depends on the velocity gradient in the boundary layer, and it decreases with the weakening of the velocity gradient. Obviously, the boundary layer The thicker it is, the smaller the velocity gradient changes and the smaller the frictional resistance, and the jet is bent under the action of the main flow and is close to the surface of the wind turbine blade. The jet fluid forms a buffer zone between the main flow and the surface of the wind turbine blade, increasing the thickness of the boundary layer. , The continuous equal-spaced airflow outlets extend and strengthen this buffering effect at the same time, thereby weakening the sweeping of the wind turbine blade surface by the mainstream, reducing the blade resistance, optimizing the blade structure, making it adaptable to more working environments and improving the wind turbine. efficient.

disclosure of invention

The purpose of the present invention is to provide a shark gill type blade drag reduction structure, blade and manufacturing method for wind turbines, which can effectively increase the thickness of the boundary layer on the surface of the wind turbine blade, reduce the velocity gradient, and control the contact between the main flow and the wall surface. , reduce the surface friction resistance and improve the power of the wind turbine.

In order to achieve the above purpose, the present invention is achieved through the following technical solutions:

A shark gill type blade drag reduction structure of a wind turbine is characterized in that the drag reduction structure is arranged on the surface of the blade and includes a groove opened on the blade, and the groove is provided with an airflow inlet and a a plurality of airflow outlets, and an airflow channel is formed between the airflow inlet and the multiple airflow outlets;

The blade rotates, the airflow enters from the airflow inlet, and passes through the airflow outlet along the airflow channel to form a jet, and the gas velocity in the airflow channel is lower than the mainstream, and the jet flowing out from the airflow outlet bends under the impact of the mainstream. A buffer area is formed between the blade surface and the main flow to reduce the friction of the main flow to the blade.

Further, the straight line distance between the two points of the front and rear edges of any cross-section of the blade provided with the drag reduction structure is c, and is set as the x-axis, and the distance from the leading edge point along the x-axis, 25%-30% c is Air inlet, 32%-34%c is the first air outlet, 36%-38%c is the second air outlet, 40%-42%c is the third air outlet, 44%-46%c is the fourth air outlet , 48%-50%c is the fifth airflow outlet.

Further, the intersection line of the airflow inlet and the blade surface is perpendicular to the x-axis.

Further, the airflow outlet profile line is parallel to the airflow inlet profile line.

Further, the drag reduction structure is arranged in the area of 60%-80% of the blade height.

A fan blade is characterized by including:

The above-mentioned fan blade drag reduction structure; and,

blade body;

The drag reduction structure is arranged on the surface of the blade body.

A method for manufacturing a fan blade, characterized in that the method comprises:

providing a blade body;

A groove is set on the surface of the blade body, the groove is provided with an air inlet and a plurality of air outlets, and an air passage is formed between the air inlet and the plurality of air outlets.

Further, the profile line of the airflow inlet and the profile line of the airflow outlet are on the profile line of the initial surface of the blade body and are parallel to each other to form the outer surface of the blade.

Further, the method includes:

Determine the initial position of the inner surface of the fan blade, and use this as the starting position of the airflow channel, the inner surface of the fan blade opens a preset distance toward the trailing edge of the blade, and the end position of the inner surface of the fan blade is used as the end position of the airflow channel .

Compared with the prior art, the present invention has the following advantages:

The drag reduction structure of shark gill blades for wind turbines is proposed for the first time. According to the structure of shark gill slits, a bionic structure is proposed, which can effectively reduce the frictional resistance of the blade surface and suppress the generation of flow loss, which can optimize the aerodynamic characteristics of the blades and prolong the wind turbine's life. service life, improve the working performance and reliability of the whole machine. It has important theoretical significance and practical application value, and provides a scientific basis for wind turbine performance improvement and optimization design.

Brief Description of Drawings

1 is a structural diagram of a shark gill blade drag reduction structure of a wind turbine of the present invention;

Fig. 2 is the middle section of the region where the drag reduction structure exists along the height direction of the blade;

Figure 3 is a partial view of the airflow inlet and outlet of the drag reduction structure.

Wherein: 1, wind turbine blade; 2, airflow inlet; 3, first airflow outlet; 4, second airflow outlet; 5, third airflow outlet; 6, fourth airflow outlet; 7, fifth airflow outlet; 8, Airflow channel; 9. Outer surface of wind turbine blade; 10. Inner surface of wind turbine blade.

Best Mode for Carrying Out the Invention

It should be noted that the terms "comprising" and "having" and any variations thereof in the description and claims of the present invention and the above-mentioned drawings are intended to cover non-exclusive inclusion, for example, a system comprising a series of units , products or devices are not necessarily limited to those units expressly listed, but may include other units not expressly listed or inherent to such products or devices.

At present, wind turbine blades are mostly made of glass fiber or high-strength composite materials. For the convenience of observation, the large-scale low-speed wind turbine blades are simplified into the wind turbine blade 1 structure, and the 60%-80% blade height range is selected as the drag reduction blade. In the existing area of the structure, 70% of the blade section is the middle section of the drag reduction structure. Connect the leading edge and trailing edge of this section with a straight line, the length is c, and set as the x-axis, and the leading edge point is 0 point. The position 25% c from the leading edge is the position where the airflow inlet 2 appears, and the length of the airflow inlet 2 is 20% of the blade height and the width is 5% c. Sharks usually have one water inlet and more than three pairs of gill slits. In this study, five gill slit-like airflow outlets were selected. The five positions of 32%-34%c, 36%-38%c, 40%-42%c, 44%-46%c, 48%-50%c are the first airflow outlet 3 and the second airflow outlet in sequence 4. The width of the third air outlet 5, the fourth air outlet 6, and the fifth air outlet 7 are all 2%c. The five airflow outlets have the same spacing and height. Since the external gill slits of sharks are approximately in the same plane as the surrounding body surface, 25%c, 30%c, 32%c, 34%c, 36%c, 38%c, 40%c, 42%c , 44%c, 46%c, 48%c, 50%c, the left and right profiles of the airflow inlet and outlet are on the surface profile of the original wind turbine blade 1 and are parallel to each other to form the outer surface 9 of the wind turbine blade. The length of the airflow channel 8 in the x-direction is 25%c and in the direction perpendicular to the x-axis is 2%c. After ensuring the width of the airflow inlet 2 in the x direction, the position of the inner surface 10 of the wind turbine blade can be determined, and this is the starting position of the airflow channel 8 until the end of the inner surface 10 of the wind turbine blade at 50c%, and the airflow channel 8 structure also ended. When the wind turbine rotates, the airflow is viscous, and a boundary layer is formed near the object. There is a velocity gradient in the boundary layer. The magnitude of the frictional resistance depends on the velocity gradient in the boundary layer. The more obvious the velocity gradient is, the greater the frictional resistance will be. When the main flow sweeps the surface of the blade, the frictional resistance loss is caused. Obviously, when the boundary layer is thicker, the frictional resistance will be smaller. When the wind turbine blade 1 of the drag reducing structure rotates, the airflow enters from the airflow inlet 2 to simulate the shark breathing process. The fifth airflow outlet is ejected from the structure of five bionic gill slits. After entering the airflow channel 8, the speed of the airflow will be lower than that of the outside mainstream, and the speed will gradually decrease during the flow of the airflow channel 8. After the jet flows out of the airflow outlet, it meets the mainstream, and the flow path of the low-energy fluid mass is bent. Fold and close to the outer surface 9 of the wind blade. The buffer area between the main flow and the outer surface 9 of the wind turbine blade is formed, the boundary layer is thickened, the velocity gradient is weakened, and the surface frictional resistance loss is reduced. When the cushioning effect of the group has not disappeared, the jet fluid group following it has appeared, the cushioning effect continues to exist and is strengthened, and will continue for a certain distance, the speed gradient in the buffer area changes less, and the frictional resistance decreases, which improves the wind turbine. The flow field around the outer surface 9 of the blade improves the working capability of the wind turbine blade 1 and improves the performance of the unit.

It should be noted that the length of the airflow inlet and airflow outlet of the above drag reduction structure can take any value of the blade height (greater than zero), the airflow inlet and airflow outlet width can take any value allowed by the width of the wind turbine blade (greater than zero), the airflow inlet and The distribution position of the airflow outlet includes the entire range of the 360° circumference of the blade. The number of airflow inlets and airflow outlets is not limited. Any value allowed by the blade width (greater than zero) can be taken. The shape of the airflow inlet and airflow outlet includes rectangle, square, Different shapes such as circle, ellipse, etc., the distances between the airflow outlets include equal intervals but are not limited to equal intervals.

The drag reduction structure of the shark gill blade of the wind turbine according to the embodiment of the present invention is described above with reference to FIGS. 1-3 . Further, the present invention can also be applied to fan blades.

A fan blade, comprising: the above-mentioned fan blade drag reduction structure; and,

blade body;

The drag reduction structure of the fan blade is arranged on the surface of the blade body.

The fan blade provided by the embodiment of the present invention has the same technical features as the vortex generator provided by the above-mentioned embodiment, so it can also solve the same technical problem and achieve the same technical effect.

It should be noted that the above-mentioned fan blades can be used in a horizontal-axis wind turbine or a vertical-axis wind turbine, and the number and rotation speed of the wind turbine blades are not limited.

The fan blade of the embodiment of the present invention is described above. Further, the present invention also discloses a method for manufacturing a fan blade, comprising the following steps:

providing a blade body;

A groove is set on the surface of the blade body, the groove is provided with an air inlet and a plurality of air outlets, and an air passage is formed between the air inlet and the plurality of air outlets;

The profile line of the airflow inlet and the profile line of the airflow outlet are on the profile line of the initial surface of the blade body and are parallel to each other to form the outer surface of the blade.

The specific embodiments of the present invention have been described above in detail, but they are only used as examples, and the present invention is not limited to the specific embodiments described above. For those skilled in the art, any equivalent modifications and substitutions made to this utility are also within the scope of the present invention. Therefore, equivalent changes and modifications made without departing from the spirit and scope of the present invention should be included within the scope of the present invention.

Claims

A shark gill type blade drag reduction structure of a wind turbine is characterized in that, the drag reduction structure is arranged on the surface of the blade, and includes a groove opened on the blade, and the groove is provided with an airflow inlet and a a plurality of airflow outlets, and an airflow channel is formed between the airflow inlet and the multiple airflow outlets;

The blade rotates, the airflow enters from the airflow inlet, and passes through the airflow outlet along the airflow channel to form a jet, and the gas velocity in the airflow channel is lower than the mainstream, and the jet flowing out from the airflow outlet bends under the impact of the mainstream. A buffer area is formed between the blade surface and the main flow to reduce the friction of the main flow to the blade.
The drag reduction structure of the shark gill blade of a wind turbine according to claim 1, wherein the straight line distance between the front and rear edges of any cross-section of the blade provided with the drag reduction structure is c, and set is the x-axis, the distance from the leading edge point along the x-axis, 25%-30%c is the airflow inlet, 32%-34%c is the first airflow outlet, 36%-38%c is the second airflow outlet, 40%- 42%c is the third airflow outlet, 44%-46%c is the fourth airflow outlet, and 48%-50%c is the fifth airflow outlet.
The drag reduction structure of the shark gill blade of a wind turbine according to claim 1, wherein the intersection line of the airflow inlet and the blade surface is perpendicular to the x-axis.
The drag reduction structure of the shark gill blade of a wind turbine according to claim 1, wherein the airflow outlet profile line is parallel to the airflow inlet profile line.
The drag reduction structure of a shark gill blade of a wind turbine according to claim 1, wherein the drag reduction structure is arranged in a 60%-80% blade height area.
A fan blade, characterized in that, comprising:

The drag reduction structure of the shark gill blade of a wind turbine as claimed in any one of claims 1 to 5; and,

blade body;

The shark gill blade drag reduction structure of the wind turbine is arranged on the surface of the blade body.
A method for manufacturing a fan blade, characterized in that the method comprises:

providing a blade body;

A groove is set on the surface of the blade body, the groove is provided with an air inlet and a plurality of air outlets, and an air passage is formed between the air inlet and the plurality of air outlets.
The method of claim 7, wherein the profile line of the airflow inlet and the profile line of the airflow outlet are on the profile line of the initial surface of the blade body and are parallel to each other to form the outer surface of the blade.
The method of claim 7, wherein the method comprises:

Determine the initial position of the inner surface of the fan blade, and use this as the starting position of the airflow channel, the inner surface of the fan blade opens a preset distance toward the trailing edge of the blade, and the end position of the inner surface of the fan blade is used as the end position of the airflow channel .