阅读说明：本技术 用于飞行的螺旋器与无人飞机 (Screw for flying and unmanned aircraft ) 是由 李鹏宇 杨延年 刘宇 于 2021-08-26 设计创作，主要内容包括：本发明公开了一种用于飞行的螺旋器与无人飞机,其中,螺旋器包括桨榖与螺旋桨,螺旋桨的一端固定连接于桨榖,并沿桨榖的径向方向延伸,桨榖用于与外部的驱动机构相连接；螺旋桨具有前缘,前缘沿其长度方向设置有多个不同波长的正弦锯齿结构,每个正弦锯齿结构沿其长度方向依次分为多个锯齿部,锯齿部的两端均为正弦锯齿结构的波谷位置,其中,不同波长的锯齿部依次交错连接,相邻两个不同波长的锯齿部之间形成波谷。在波谷的位置,两种波长的锯齿部由于其形状不同对湍流涡旋作用时,导致湍流涡旋在波谷间对流所花费的时间不同而导致相位差,因此波谷位置的两种锯齿部使噪声源发生破坏性的干涉,从而产生更好的降噪效果。(The invention discloses a propeller for flying and an unmanned aerial vehicle, wherein the propeller comprises a hub and a propeller, one end of the propeller is fixedly connected with the hub and extends along the radial direction of the hub, and the hub is used for being connected with an external driving mechanism; the screw has the leading edge, and the leading edge is provided with the sinusoidal sawtooth structure of a plurality of different wavelengths along its length direction, and every sinusoidal sawtooth structure divide into a plurality of sawtooth parts along its length direction in proper order, and the both ends of sawtooth part are sinusoidal sawtooth structure's trough position, and wherein, the sawtooth part of different wavelengths is staggered connection in proper order, forms the trough between the sawtooth part of two adjacent different wavelengths. At the positions of the wave troughs, when the sawtooth parts with two wavelengths act on turbulent eddies due to different shapes, the time spent by the turbulent eddies in convection among the wave troughs is different, so that phase difference is caused, and the two sawtooth parts at the positions of the wave troughs cause destructive interference of noise sources, thereby generating better noise reduction effect.)

1. The propeller for flying is characterized by comprising a hub and a propeller, wherein one end of the propeller is fixedly connected with the hub and extends along the radial direction of the hub, and the hub is used for being connected with an external driving mechanism;

the screw has the leading edge, the leading edge is followed the length direction of leading edge is provided with the sinusoidal sawtooth structure of a plurality of different wavelengths, every sinusoidal sawtooth structure is followed sinusoidal sawtooth structure length direction divide into a plurality of sawtooth parts in proper order, the both ends of sawtooth part are the trough position of sinusoidal sawtooth structure, wherein, different wavelengths sawtooth part is staggered connection in proper order, adjacent two different wavelengths form the trough between the sawtooth part.

2. The augur for flight of claim 1, wherein each said propeller has two said sinusoidal saw tooth structures, a first sinusoidal saw tooth structure and a second sinusoidal saw tooth structure; the first sinusoidal sawtooth structure is divided into a plurality of first sawtooth parts along the length direction of the first sinusoidal sawtooth structure, and the wavelength of the first sinusoidal sawtooth structure is lambda₁(ii) a The second sinusoidal sawtooth structure is divided into a plurality of second sawtooth parts along the length direction of the second sinusoidal sawtooth structure, and the wavelength of the second sinusoidal sawtooth structure is lambda₂；

Wherein the first sawtooth part and the second sawtooth part are sequentially connected in a staggered manner, and the wave trough is formed between the first sawtooth part and the second sawtooth part, lambda is formed between the first sawtooth part and the second sawtooth part₁≠λ₂。

3. The propeller of claim 2, wherein there are two of the propellers, two of the propellers being in a common line, the distance between the end of one propeller away from the hub and the end of the other propeller away from the hub being between 106mm and 306 mm;

wherein the ratio of the wave height of the first sinusoidal sawtooth structure to the reference chord length of the propeller ranges between 0.033 and 0.167, and the ratio of the wave height of the second sinusoidal sawtooth structure to the reference chord length of the propeller ranges between 0.033 and 0.167.

4. The auger for flying of claim 3, wherein the wave height of the first sinusoidal saw tooth structure is 2H1, and the wave height of the second sinusoidal saw tooth structure is 2H2, 2H1 ═ 2H 2.

5. The propeller of claim 2, wherein there are two of the propellers, two of the propellers being in a common line, the distance between the end of one propeller away from the hub and the end of the other propeller away from the hub being between 106mm and 306 mm;

wherein the ratio of the wavelength of the first sinusoidal sawtooth structure to the reference chord length of the propeller ranges between 0.1 and 0.3, and the ratio of the wavelength of the second sinusoidal sawtooth structure to the reference chord length of the propeller ranges between 0.1 and 0.3.

6. The auger for flying of claim 5, wherein a ratio between a wavelength of the first sinusoidal saw tooth structure and a wavelength of the second sinusoidal saw tooth structure is between 0.33 and 3.

7. The auger for flying of claim 1, wherein the serrations are extensions provided to the leading edge.

8. The propeller of claim 1, wherein the leading edge includes a reserved area and a serrated area along a length of the leading edge, the reserved area being disposed proximate to the hub, the serrated area being disposed distal to the hub, the sinusoidal serrations being disposed in the serrated area.

9. The auger for flying of claim 8, wherein the length of the serrated region is half the length of the leading edge.

10. An unmanned aircraft, comprising a screw for flight according to any one of claims 1 to 9.

Technical Field

The invention relates to the technical field of unmanned aerial vehicles, in particular to a screw for flying and an unmanned aerial vehicle.

Background

In the related art, the commercial market for small multi-rotor aircraft has been growing rapidly in the past few years, providing effective solutions for image capture, smart transportation and smart agriculture, but the aerodynamic noise of drones is a key factor that restricts their application in some situations. In order to meet the requirement of small multi-rotor aircraft for low noise, it is more and more important to design the noise reduction of the screw.

Disclosure of Invention

The present invention is directed to solving at least one of the problems of the prior art. Therefore, the invention provides a screw machine and an unmanned aircraft for flying, which can reduce the noise generated when the screw machine is used.

The invention also provides an unmanned aircraft with the screw for flying.

According to the screw used for flying of the embodiment of the invention, the screw comprises a propeller hub and a propeller, wherein one end of the propeller is fixedly connected with the propeller hub and extends along the radial direction of the propeller hub, and the propeller hub is used for being connected with an external driving mechanism;

the screw has the leading edge, the leading edge is followed the length direction of leading edge is provided with the sinusoidal sawtooth structure of a plurality of different wavelengths, every sinusoidal sawtooth structure is followed sinusoidal sawtooth structure length direction divide into a plurality of sawtooth parts in proper order, the both ends of sawtooth part are the trough position of sinusoidal sawtooth structure, wherein, different wavelengths sawtooth part is staggered connection in proper order, adjacent two different wavelengths form the trough between the sawtooth part.

The screw for flying according to the embodiment of the invention has at least the following beneficial effects: by adopting the scheme, the external motor drives the hub to rotate, and the propeller and the hub rotate synchronously; during the rotation of the propeller, the sawtooth parts with different wavelengths enable the front edge of the propeller to have sawtooth inclined edges, so that the surface pressure pulsation of the front edge shows a truncation effect, thereby reducing the radiation sound power level and reducing the noise generated by the propeller. Further, in the scheme of the application, the saw tooth parts with different wavelengths generate different noise reduction frequencies, and when the propeller works, the noise source of the wave trough is dominant. Adopt the sawtooth structure of multiple different wavelength to make the sawtooth portion of different wavelength staggered connection in proper order, the trough is formed between the sawtooth portion of two different wavelengths, and so design is exactly to the noise source of trough department. Specifically, when the propeller works, at the positions of the wave troughs, the sawtooth parts with two wavelengths have different shapes and act on turbulent eddies, so that the time spent by the turbulent eddies in convection among the wave troughs is different, the phase difference is caused, and the two sawtooth parts at the positions of the wave troughs cause destructive interference of a noise source, thereby generating a better noise reduction effect.

According to some embodiments of the invention, each of said propellers has two of said sinusoidal saw tooth structures, respectively a first sinusoidal saw tooth structure and a second sinusoidal saw tooth structure; the first sinusoidal sawtooth structure is divided into a plurality of first sawtooth parts along the length direction of the first sinusoidal sawtooth structure, and the wavelength of the first sinusoidal sawtooth structure is lambda₁(ii) a The second sinusoidal sawtooth structure is divided into a plurality of second sawtooth parts along the length direction of the second sinusoidal sawtooth structure, and the wavelength of the second sinusoidal sawtooth structure is lambda₂(ii) a Wherein the first sawtooth part and the second sawtooth part are sequentially connected in a staggered manner, and the wave trough is formed between the first sawtooth part and the second sawtooth part, lambda is formed between the first sawtooth part and the second sawtooth part₁≠λ₂。

According to some embodiments of the invention, the propeller has two, two of the propellers are located on the same line, and the distance between the end of one propeller away from the hub and the end of the other propeller away from the hub is between 106mm and 306 mm; wherein the ratio of the wave height of the first sinusoidal sawtooth structure to the reference chord length of the propeller ranges between 0.033 and 0.167, and the ratio of the wave height of the second sinusoidal sawtooth structure to the reference chord length of the propeller ranges between 0.033 and 0.167.

According to some embodiments of the invention, the wave height of the first sinusoidal saw tooth structure is 2H1, and the wave height of the second sinusoidal saw tooth structure is 2H2, 2H1 being 2H 2. .

According to some embodiments of the invention, the propeller has two, two of the propellers are located on the same straight line, and the distance between one end of one propeller away from the hub and one end of the other propeller away from the hub is between 106mm and 306 mm; wherein the ratio of the wavelength of the first sinusoidal sawtooth structure to the reference chord length of the propeller ranges between 0.1 and 0.3, and the ratio of the wavelength of the second sinusoidal sawtooth structure to the reference chord length of the propeller ranges between 0.1 and 0.3.

According to some embodiments of the invention, a ratio between a wavelength of the first sinusoidal sawtooth structure and a wavelength of the second sinusoidal sawtooth structure is between 0.33 and 3.

According to some embodiments of the invention, the serrations are extensions provided to the leading edge.

According to some embodiments of the present invention, the front edge includes a reserved area and a sawtooth area along a length direction of the front edge, the reserved area is disposed near the hub, the sawtooth area is disposed far from the hub, and the sinusoidal sawtooth structure is disposed in the sawtooth area.

According to some embodiments of the invention, the length of the serrated region is half the length of the leading edge.

The unmanned aerial vehicle comprises the unmanned aerial vehicle.

The unmanned aircraft provided by the embodiment of the invention has at least the following beneficial effects: the unmanned aircraft adopts the screw propeller which adopts a sine sawtooth structure with various wavelengths. Experiments show that the sawtooth parts with different wavelengths generate different noise reduction frequencies; moreover, when the propeller works, the noise source of the wave trough is dominant. In this application scheme, adopt the sawtooth structure of multiple different wavelength to make the sawtooth portion of different wavelength staggered connection in proper order, the trough is formed between the sawtooth portion of two different wavelengths, so design, just is to the noise source of trough department. Specifically, when the propeller works, at the positions of the wave troughs, the sawtooth parts with two wavelengths have different shapes and act on turbulent eddies, so that the time spent by the turbulent eddies in convection among the wave troughs is different, the phase difference is caused, and the two sawtooth parts at the positions of the wave troughs cause destructive interference of a noise source, thereby generating a better noise reduction effect. To sum up, when unmanned aerial vehicle flies, because only produce less noise when the spiral ware uses, unmanned aerial vehicle is applicable to more occasions.

Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.

Drawings

The invention is further described with reference to the following figures and examples, in which:

FIG. 1 is an angular view of a screw according to an embodiment of the present invention;

FIG. 2 is another angular view of the screw according to the embodiment of the present invention;

fig. 3 is a partial schematic view of a propeller of a screw propeller according to an embodiment of the present invention.

Reference numerals:

the propeller 100, the hub 110, the propeller 120, the leading edge 121, the serration region 1211, the reserved region 1212, the suction surface 122, the pressure surface 123, the first sinusoidal serration structure 124, the first serration 1241, the second sinusoidal serration structure 125, the second serration 1251, and the wave trough 126.

Detailed Description

Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the accompanying drawings are illustrative only for the purpose of explaining the present invention, and are not to be construed as limiting the present invention.

In the description of the present invention, it should be understood that the orientation or positional relationship referred to in the description of the orientation, such as the upper, lower, front, rear, left, right, etc., is based on the orientation or positional relationship shown in the drawings, and is only for convenience of description and simplification of description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus, should not be construed as limiting the present invention.

In the description of the present invention, the meaning of a plurality is one or more, the meaning of a plurality is two or more, and the above, below, exceeding, etc. are understood as excluding the present numbers, and the above, below, within, etc. are understood as including the present numbers. If the first and second are described for the purpose of distinguishing technical features, they are not to be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated or implicitly indicating the precedence of the technical features indicated.

In the description of the present invention, unless otherwise explicitly limited, terms such as arrangement, installation, connection and the like should be understood in a broad sense, and those skilled in the art can reasonably determine the specific meanings of the above terms in the present invention in combination with the specific contents of the technical solutions.

In the description of the present invention, reference to the description of the terms "one embodiment," "some embodiments," "an illustrative embodiment," "an example," "a specific example," or "some examples," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

According to a first aspect of the present invention, a flight propeller 100 is disclosed, referring to fig. 1 to 2, the propeller 100 includes a hub 110 and a propeller 120, one end of the propeller 120 is fixedly connected to the hub 110 and extends along a radial direction of the hub 110, the hub 110 is used for connecting with an external driving mechanism; the propeller 120 has a leading edge 121, and the leading edge 121 is provided with the sinusoidal sawtooth structure of a plurality of different wavelengths along its length direction, and every sinusoidal sawtooth structure divide into a plurality of sawtooth parts along its length direction in proper order, and the both ends of sawtooth part are the trough 126 position of sinusoidal sawtooth structure, and wherein, the sawtooth part of different wavelengths is staggered connection in proper order, forms trough 126 between the sawtooth part of two adjacent different wavelengths.

By adopting the above scheme, the external motor drives the hub 110 to rotate, and the propeller 120 and the hub 110 rotate synchronously; wherein, the sawtooth parts with different wavelengths all make the front edge 121 of the propeller 120 have sawtooth inclined edges during the rotation of the propeller 120, so that the surface pressure pulsation of the front edge 121 shows a truncation effect, thereby causing the radiation sound power level to be reduced and reducing the noise generated by the propeller 120.

In the present embodiment, the saw teeth with different wavelengths generate different noise reduction frequencies, and the noise source of the wave trough 126 is dominant when the propeller 120 is in operation. Adopt the sawtooth structure of multiple different wavelength to make the sawtooth of different wavelength in proper order cross-under connection, trough 126 forms between the sawtooth of two different wavelengths, so design, is exactly to the noise source of trough 126 department. Specifically, when the propeller 120 is in operation, at the positions of the wave troughs 126, the sawtooth parts with two wavelengths act on turbulent eddies due to different shapes, so that the time spent by the turbulent eddies in convection between the wave troughs 126 is different, and a phase difference is caused, and therefore, the two sawtooth parts at the positions of the wave troughs 126 cause destructive interference of noise sources, so that a better noise reduction effect is generated.

In some embodiments, one surface of the propeller 120 is defined as a suction surface and the other surface of the propeller 120 is defined as a pressure surface, the pressure on the suction surface being lower than the air pressure surrounding the aircraft and the pressure surface being higher than the air pressure surrounding the aircraft, such that the pressure differential between the suction surface and the pressure surface creates the upward pulling force required by the aircraft.

In some embodiments, referring to fig. 2 and 3, each propeller 120 has two sinusoidal saw tooth structures, a first sinusoidal saw tooth structure 124 and a second sinusoidal saw tooth structure 125; wherein, the first sinusoidal sawtooth structure 124 is divided into a plurality of first sawtooth parts 1241 along the length direction thereof, the wavelength of the first sinusoidal sawtooth structure 124 is λ₁(ii) a The second sinusoidal sawtooth structure 125 is divided into a plurality of second sawtooth portions 1251 along the length direction thereof, and the second sinusoidal sawtooth structure 125 has a wavelength λ₂(ii) a Wherein, the first sawtooth part 1241 and the second sawtooth part 1251 are sequentially connected in a staggered manner, and the wave trough 126, λ, is formed between the first sawtooth part 1241 and the second sawtooth part 1251₁≠λ₂。

By adopting the scheme, each propeller 120 is only designed with two saw-tooth structures, so that the front edge 121 of the propeller 120 has a simpler structure and lower manufacturing difficulty; meanwhile, the wavelength of the first sinusoidal sawtooth structure 124 is different from the wavelength of the second sinusoidal sawtooth structure 125, so that the first sawtooth portion 1241 and the second sawtooth portion 1251 can perform preferable noise reduction on the propeller 120 when the propeller 120 is used.

It will be appreciated that the first serrations 1241 correspond one-to-one to the second serrations 1251, and that the configuration of each of the valleys 126 is such that when air flows over the locations of the valleys 126, substantially the same noise radiation is generated at each of the valleys 126. During operation of the propeller 120, each of the valleys 126 is a source of sound of one and the same frequency interfering with another source of the same frequency, such that the valleys 126 have a significant and destructive interference with the source of the noise sound, thereby providing a better noise reduction effect.

In some embodiments, in the present embodiment, there are two propellers 120, two propellers 120 are located on the same line, and the distance between the end of one propeller 120 away from the hub 110 and the end of the other propeller 120 away from the hub 110 is between 306mm and 106 mm. Based on the above-mentioned standard of the screw 100, the ratio of the wave height 2H1 of the first sinusoidal sawtooth structure 124 to the reference chord length of the propeller 120 is in the range of 0.033 and 0.167, and the ratio of the wave height 2H2 of the second sinusoidal sawtooth structure 125 to the reference chord length of the propeller 120 is in the range of 0.033 and 0.167. The reference chord length is represented by c0.75R, which is a chord length of 0.75 times the radius of the propeller 120, and therefore, 0.033. ltoreq.2H 1/c0.75R. ltoreq.0.167, and 0.033. ltoreq.2H 2/c0.75R. ltoreq.0.167.

In this application scheme, the sinusoidal sawtooth structure of different ripples height can fall the noise of making an uproar to the noise of different frequencies. The first sinusoidal sawtooth structure 124 and the second sinusoidal sawtooth structure 125 adopt the above dimensions, so that the noise reduction object of the first sinusoidal sawtooth structure 124 and the noise reduction object of the second sinusoidal sawtooth structure 125 are both medium-high frequency broadband noise above 5000 Hz; the human ear is most sensitive to the noise of about 4000Hz, the sawtooth height range selected by the design can effectively reduce the intermediate frequency broadband noise of about 5000Hz, the conventional sine sawtooth structure can only effectively reduce the noise of about 7000Hz, and the size of 5000Hz is closer to that of 4000Hz, so that the stimulation of the noise to the human ear can be reduced to the maximum degree.

It is understood that, as shown in fig. 3, the wave height 2H1 is a height from the bottom of the wave trough 126 to the peak of the first serration 1241, and the wave height 2H2 is a height from the bottom of the wave trough 126 to the peak of the second serration 1251.

Further, referring to fig. 1 and 2, the wave height 2H1 of the first sinusoidal sawtooth structure 124 is the same as the wave height 2H2 of the second sinusoidal sawtooth structure 125, so that the wave height of the first sinusoidal sawtooth structure 124 and the wave height of the second sinusoidal sawtooth structure 125 enhance the attenuation effect of the noise in the specific frequency region, thereby more effectively reducing the mid-frequency broadband noise which is as low as about 5000 Hz.

In some embodiments, there are two propellers 120, the two propellers 120 being in the same line, the distance between the end of one propeller 120 away from the hub 110 and the end of the other propeller 120 away from the hub 110 being between 306mm and 106 mm. Based on the above criteria of the spiral 100, the wavelength λ of the first sinusoidal sawtooth structure 124₁The ratio of the reference chord length of the propeller 120 ranges between 0.1 and 0.3, and the wavelength λ of the second sinusoidal sawtooth structure 125₂The ratio to the reference chord length of the propeller 120 ranges between 0.1 and 0.3; the reference chord length is 0.75 times the chord length of the propeller 120 at the radius, and is represented as c0.75r, and therefore, λ is 0.1 ≦ λ₁/c0.75R≤0.3，0.1≤λ₂/c0.75R≤0.3。

In the experimental process, a plurality of propellers 120 with different wavelengths are designed, and the propellers 120 are tested, so that the thrust, power and noise reduction of each propeller 120 are obtained; thereafter, the feedback effect of each propeller 120 is analyzed, the wavelength of the first sinusoidal sawtooth structure 124 and the wavelength of the second sinusoidal sawtooth structure 125 satisfy the above-mentioned size requirement, the thrust of the propeller 100 is large enough, the power is small enough, and the noise reduction effect of the propeller 100 is good.

It will be appreciated that, as shown in FIG. 3, the wavelength λ₁Is the distance between the two ends of the first sawtooth part 1241, the wavelength lambda₂Which is the distance between both ends of the second indented portion 1251.

Further, referring to fig. 1 and 2, the wavelength λ of the first sinusoidal sawtooth structure 124₁And the wavelength λ of the second sinusoidal sawtooth structure 125₂The ratio between 0.33 and 3, i.e. 0.33. ltoreq. lambda₂/λ₁Less than or equal to 3. In the experimental process, a plurality of propellers 120 with different wavelengths are designed, and the propellers 120 are tested, so that the thrust, power and noise reduction of each propeller 120 are obtained; thereafter, the feedback effect of each propeller 120 is analyzed, the wavelength of the first sinusoidal sawtooth structure 124 and the wavelength of the second sinusoidal sawtooth structure 125 satisfy the above ratio requirement, the thrust of the propeller 100 is large enough, the power is small enough, and the noise reduction effect of the propeller 100 is good.

In some embodiments, the sawtooth parts are extensions disposed on the leading edge 121, that is, the first sawtooth part 1241 and the second sawtooth part 1251 are extensions disposed on the leading edge 121, and it can be seen that the design is an extended design of a sinusoidal sawtooth structure based on the reference propeller 120, which increases the area of the propeller 120 and is beneficial to obtain better aerodynamic performance.

In some embodiments, the leading edge 121 includes a reserved area 1212 and a sawtooth area 1211 along a length thereof, and the sinusoidal sawtooth structure is disposed in the sawtooth area 1211. Specifically, the end of the propeller 120 close to the hub 110 is a root, the end of the propeller 120 far from the hub 110 is a tip, the reserved area 1212 is arranged close to the root, and the serration area 1211 is arranged close to the tip. Experiments show that the sawtooth part can effectively reduce medium-high frequency broadband noise of turbulence-wing type or vortex-wing type. During rotation of the propeller 120, the propeller 120 is at a high speed near the tip, and the vortex intensity and turbulence are high, and vice versa near the root. Therefore, the serration region 1211 is selected to have an extended sinusoidal serration structure in a half of the area of the propeller 120 away from the hub 110.

In a second aspect of the invention, an unmanned aircraft is disclosed, comprising the screw 100 described above. The unmanned aircraft adopts the screw propeller 100, and the propeller 120 of the screw propeller 100 adopts a sine sawtooth structure with various wavelengths. Experiments show that the sawtooth parts with different wavelengths generate different noise reduction frequencies; also, the noise source of the valleys 126 is dominant when the propeller 120 is operating. In this application scheme, adopt the sawtooth structure of multiple different wavelength to make the sawtooth portion of different wavelength staggered connection in proper order, trough 126 forms between the sawtooth portion of two different wavelengths, so design, is exactly to the noise source of trough 126 department. Specifically, when the propeller 120 is in operation, at the positions of the wave troughs 126, the sawtooth parts with two wavelengths act on turbulent eddies due to different shapes, so that the time spent by the turbulent eddies in convection between the wave troughs 126 is different, and a phase difference is caused, and therefore, the two sawtooth parts at the positions of the wave troughs 126 cause destructive interference of noise sources, so that a better noise reduction effect is generated. To sum up, when unmanned aerial vehicle flies, because only produce less noise when spiral 100 uses, unmanned aerial vehicle is applicable to more occasions.

The embodiments of the present invention have been described in detail with reference to the accompanying drawings, but the present invention is not limited to the above embodiments, and various changes can be made within the knowledge of those skilled in the art without departing from the gist of the present invention. Furthermore, the embodiments of the present invention and the features of the embodiments may be combined with each other without conflict.