A rotor blade with surface texture pattern

Abstract

A rotor blade having a surface micro-pattern formed according to the present invention comprises a rotor blade body that is provided in an unmanned aerial vehicle and rotates around a coupling part to generate thrust necessary for the flight of the unmanned aerial vehicle, and a pattern part formed on the surface of the rotor blade body to reduce noise generated as the rotor blade body rotates. The pattern part may be formed with a gradient structure in which the diameter decreases toward the edge of the rotor blade body to correspond to the airfoil shape of the rotor blade body, and is formed with a pattern structure that is spaced apart from each other and repeated based on the length and width directions of the rotor blade body, thereby dispersing the flow of vortices generated around the rotor blade body to reduce noise caused by the rotation of the rotor blade body.

Description

Technology Field

[0001] The present invention relates to a rotor blade having a surface micro-pattern formed thereon, and more specifically, to a rotor blade having a surface micro-pattern formed thereon that can reduce noise without degrading flight performance during flight of an unmanned aerial vehicle by forming a micro-pattern on the surface of a rotor equipped in an unmanned aerial vehicle. Background Technology

[0003] Drones, a type of unmanned aerial vehicle, are being utilized in a wide range of fields, from public sectors such as disaster response, aerial photography, traffic system analysis, and crime prevention, to broadcast filming and video transmission, internet or communication service platforms, agriculture and fisheries, exploration and research, and even unmanned delivery; the market size is growing rapidly.

[0004] A general drone may include a body, a thrust generating device for providing thrust to the body to make the body fly, and a camera unit equipped on the body for performing a given mission such as monitoring.

[0005] A thrust generating device generally includes a propeller (rotor) and a motor to rotate the propeller, and generates thrust in the body through the high-speed rotation of the propeller.

[0006] For these conventional drones to be utilized and become an integral part of our daily lives, safety and noise issues caused by high-speed rotating propellers must be resolved.

[0007] In other words, while multiple high-speed rotating propellers are essential for a drone to generate thrust, the aerodynamic noise generated by these high-speed propellers acts as a significant stress on the surrounding environment in which the drone flies.

[0008] Small drones sold on the market generate noise of about 70 to 80 dB within a radius of 1 meter, which is a loud noise similar to the noise of using a vacuum cleaner.

[0009] According to preliminary findings listed in NASA’s ‘Psychoacoustic Characteristics of Noise in Small Unmanned Aerial Systems,’ it was reported that when people hear noise from cars and drones at the same intensity, they perceive the noise from drones as more than twice as loud as the noise from cars.

[0010] In addition, through joint research programs among European countries (HELISHAPE, HELINOISE, etc.), design proposals have been presented to change the shape of the blades for the purpose of reducing noise without degrading performance, and recently, research has been conducted to reduce noise while minimizing thrust loss by forming micro-serrations on rotor blades for small drones by mimicking the wing structure of an owl.

[0011] However, these micro-protrusions are structurally weak and highly susceptible to damage from external impacts or pressure from the rotation of rotor blades, which actually reduces stability during drone flight and necessitates a more robust structural design. Furthermore, even if noise is reduced by altering the shape of the rotor blades, thrust is also reduced, leading to a problem where the drone's flight performance is degraded.

[0012] Therefore, a method to resolve these problems is required. Prior art literature

[0014] Republic of Korea Registered Patent Publication No. 10-2160416 The problem to be solved

[0015] The present invention is an invention devised to solve the problems of the aforementioned prior art, and has the purpose of reducing noise by forming a micro-pattern on the surface of the rotor blade to disperse the flow of vortices generated around the rotor blade rotating at high speed, while maintaining the flight capability of the unmanned aerial vehicle by maintaining the specifications or shape of the rotor blade.

[0016] The problems of the present invention are not limited to those mentioned above, and other unmentioned problems will be clearly understood by those skilled in the art from the description below. means of solving the problem

[0018] The rotor blade having a surface micro-pattern formed according to the present invention for achieving the above-mentioned purpose comprises a rotor blade body that is provided in an unmanned aerial vehicle and rotates around a coupling part to generate thrust necessary for the flight of the unmanned aerial vehicle, and a pattern part formed on the surface of the rotor blade body to reduce noise generated as the rotor blade body rotates, wherein the pattern part is formed with a repeating pattern structure spaced apart from each other based on the longitudinal and width directions of the rotor blade body, thereby dispersing the flow of vortices generated around the rotor blade body and reducing noise caused by the rotation of the rotor blade body.

[0019] The rotor blade body is provided in an unmanned aerial vehicle and rotates around a coupling part to generate thrust necessary for the flight of the unmanned aerial vehicle, and the rotor blade body is formed on the surface of the rotor blade body to reduce noise generated as the rotor blade body rotates. The rotor blade body is formed with a repeating pattern structure that is spaced apart from each other based on the longitudinal and transverse directions of the rotor blade body, thereby dispersing the flow of vortices generated around the rotor blade body to reduce noise caused by the rotation of the rotor blade body. The rotor blade body may also be formed with a gradation structure in which the diameter decreases towards the edge of the rotor blade body to correspond to the airfoil shape of the rotor blade body, which becomes thinner towards the edge.

[0020] At this time, the pattern portion is formed with a grid-shaped square grid pattern structure, and the spacing between them can be adjusted based on the length direction and width direction of the rotor blade body.

[0021] In addition, the pattern portion may be formed on the surface of the rotor blade body as either an intaglio through a subtraction operation or a relief through an addition operation.

[0022] At this time, the above gradient structure is,

[0023] The rotor blade body may be formed in at least one of four directions, including the longitudinal and transverse directions. Effects of the invention

[0025] The rotor blade having a surface micropattern formed thereon according to the present invention for solving the above-mentioned problem has the following effects.

[0026] First, by maintaining the size and shape of the rotor blades and forming a fine pattern on the surface, the thrust for flight of the unmanned aerial vehicle is maintained to the maximum extent, while the noise generated by the high-speed rotation of the rotor blades is reduced.

[0027] Second, it can be applied to existing rotor blades, so that only fine patterns can be formed without replacing the entire blade, thereby minimizing the economic burden.

[0028] Third, by maintaining the thrust of the unmanned aerial vehicle while reducing only the noise, there is an advantage in that the application range of the unmanned aerial vehicle can be stably expanded.

[0029] The effects of the present invention are not limited to those mentioned above, and other unmentioned effects will be clearly understood by those skilled in the art from the description in the claims. Brief explanation of the drawing

[0031] FIG. 1 is an exemplary diagram showing the appearance of an unmanned aerial vehicle having a rotor blade with a surface micropattern formed thereon according to an embodiment of the present invention; FIG. 2 is an exemplary diagram showing a pattern portion in which a square grid pattern in the shape of a grid is formed as an intaglio in a rotor blade having a surface micropattern formed according to an embodiment of the present invention; FIG. 3 is an experimental graph showing noise reduction and thrust efficiency according to the adjustment of the mutually spaced interval of the pattern portions in a rotor blade having a surface micropattern formed according to an embodiment of the present invention; FIG. 4 is an exemplary diagram showing a pattern portion in which a square grid pattern in the shape of a grid is formed in relief, in a rotor blade having a surface micropattern formed according to another embodiment of the present invention; FIG. 5 is an exemplary diagram showing a pattern portion formed with a gradient structure in a rotor blade having a surface micropattern formed according to an embodiment of the present invention; FIG. 6 is an exemplary diagram showing the process of forming a pattern portion having a gradient structure on a general rotor blade in a rotor blade having a surface micropattern formed according to an embodiment of the present invention; FIG. 7 is an exemplary diagram showing the process of applying a bidirectional gradient structure to a rotor blade having a surface micropattern formed according to an embodiment of the present invention; FIG. 8 is an experimental graph showing a pattern portion having various patterns and noise reduction efficiency according to the same, in a rotor blade having a surface micropattern formed according to an embodiment of the present invention; and FIG. 9 is an experimental graph comparing noise and thrust for various patterns in a rotor blade having a surface micropattern formed according to an embodiment of the present invention. Specific details for implementing the invention

[0032] Preferred embodiments of the present invention, in which the objectives of the present invention can be specifically realized, will be described below with reference to the attached drawings. In describing these embodiments, the same names and reference numerals are used for identical components, and additional explanations thereof will be omitted.

[0033] The present invention relates to a rotor blade having a surface micro-pattern formed thereon, which can reduce noise without degrading flight performance during flight of an unmanned aerial vehicle such as a drone by forming a micro-pattern on the surface of a rotor equipped in the unmanned aerial vehicle.

[0034] As shown in FIG. 1, the rotor blade (A) having a surface micro-pattern formed thereon according to the present invention is rotatably coupled to one unmanned aerial vehicle to generate thrust necessary for the flight of the unmanned aerial vehicle. Since the coupling structure between the rotor blade (A) and the unmanned aerial vehicle is a generally well-known structure, a detailed description is omitted in the present invention.

[0035] According to one embodiment of the present invention, the rotor blade (A) may be provided on the unmanned aerial vehicle as shown in FIG. 2 and may comprise a rotor blade body (100) that generates thrust necessary for the flight of the unmanned aerial vehicle by rotating at high speed around a coupling part coupled to the unmanned aerial vehicle, and a pattern part (200) that can be formed on the surface of the rotor blade body (100) to reduce noise generated as the rotor blade body (100) rotates.

[0036] The above pattern portion (200) is formed in a shape that surrounds the outer surface of the rotor blade body (100), but is not formed to surround the entire outer surface of the rotor blade body (100) face-to-face, but can be formed as a pattern structure that is spaced apart from each other based on the length direction and width direction of the rotor blade body (100), and when the unmanned aerial vehicle flies, the flow of vortices generated around the rotor blade body (100) rotating at high speed is dispersed by the pattern portion (200) formed on the surface of the rotor blade body (100), thereby allowing the noise caused by the high-speed rotation of the rotor blade body (100) to be reduced.

[0037] According to one embodiment of the present invention, the pattern portion (200) may be formed as a pattern that is spaced apart from each other and repeated based on the length direction and width direction of the rotor blade body (100) as described above, more specifically, as a square grid pattern structure in the shape of a grid. At this time, by making the spacing between the patterns spaced apart from each other based on the length direction and width direction of the rotor blade body (100) adjustable, noise reduction and thrust efficiency may be applied differently depending on the size or specifications of the existing rotor blade and the unmanned aerial vehicle equipped with it, or the purpose of operation, thereby allowing the pattern portion (200) having the most optimal fine pattern structure to be formed for the rotor blade of the unmanned aerial vehicle.

[0038] For example, when the pattern portion (200) is formed on the surface of the rotor blade (A) made of the same specifications, if the pattern spacing of the pattern portion (200) is different, the noise reduction and thrust efficiency of the rotor blade (A) may differ. In the case of the unmanned aerial vehicle to be operated, if the proportion of noise reduction efficiency is greater, a pattern portion (200) that maximizes noise reduction efficiency may be formed. If the proportion of thrust efficiency is greater than noise reduction efficiency, a pattern portion (200) that maximizes thrust efficiency relatively more than noise reduction efficiency may be formed.

[0039] FIG. 3 is an experimental graph showing that noise reduction efficiency and propulsion efficiency are controlled by controlling the surface density (Area density) of the rotor blade body (100) by forming the pattern portion (200) on the surface of the rotor blade body (100) in such a way that the pattern portion (200) is formed with different spacing between patterns based on the length direction and width direction of the rotor blade body (100).

[0040] Referring to FIG. 3, an embodiment according to the present invention is described more specifically as follows: the rotor blade (A) is installed within a certain space, a sound level meter is installed at a position 1m away from the rotor blade (A), and a load cell is installed on the rotor blade (A). The noise and thrust generated by rotating the rotor blade (A) for a certain period of time are measured, while the pattern spacing of the pattern portion (200) formed on the rotor blade body (100) of the rotor blade (A) is varied and measured repeatedly. When the results are compared, first, the width direction pattern spacing of the pattern portion (200) based on the width direction of the rotor blade body (100) When measuring with 3, 4, and 5 respectively, The noise generated was the lowest when, It can be seen that the generated noise actually increases in that case.

[0041] Subsequently, the pattern spacing of the pattern section (200) based on the width direction of the rotor blade body (100) where the smallest noise is generated Fix it to 4, and adjust the pattern spacing of the pattern section (200) differently based on the longitudinal direction of the rotor blade body (100), so that the longitudinal pattern spacing of the pattern section (200) When measured with values ​​of 10, 15, and 20, respectively, When and When, the thrust for the unmanned aerial vehicle increased, but When it happens Since the generation of noise was found to be relatively greater than when..., generally, the noise reduction efficiency and propulsion efficiency are such that the pattern part (200) is in the longitudinal direction of the rotor blade body (100). , width direction It is most desirable for the pattern to be formed in this way, but it is not limited thereto. As described above, it should be noted that the mutual spacing between the patterns of the pattern section (200) may be formed differently depending on whether noise reduction efficiency or propulsion efficiency is maximized when operating the unmanned aerial vehicle.

[0042] According to one embodiment of the present invention, the pattern portion (200) is formed on the surface of the rotor blade body (100) in a shape that surrounds the outer circumference of the rotor blade body (100) so as to correspond to the shape of the rotor blade body (100), more specifically, the shape of the rotor blade body (100) having an airfoil shape in which the thickness decreases toward the edge, and is preferably formed in a gradation structure in which the diameter decreases toward the edge of the rotor blade body (100).

[0043] Here, the diameter of the pattern portion (200) formed on the rotor blade body (100) is understood to mean the depth of formation of the pattern portion (200) when the pattern portion (200) is formed on the surface of the rotor blade body (100) through a subtraction operation during Boolean operation as shown in FIG. 2, and the height of the pattern portion (200) when the pattern portion (200) is formed through an addition operation during Boolean operation as shown in FIG. 4, that is, the height of formation of the pattern portion (200) that protrudes outwardly when formed on the surface of the rotor blade body (100).

[0044] For example, as illustrated in FIG. 2, the pattern portion (200) formed on the rotor blade body (100) is formed on the surface of the rotor blade body (100) and is formed as an intaglio by being inserted into a certain depth in the inward direction. Due to the characteristics of the rotor blade body (100) having an airfoil shape in which the thickness becomes thinner towards the edge, the pattern portion (200) formed as an intaglio on the surface of the rotor blade body (100) is formed as a gradient structure in which the depth formed becomes shallower towards the edge of the rotor blade body (100) so as to prevent the rotor blade body (100) from being damaged by the pattern portion (200) and thus secure the structural stability of the rotor blade body (100).

[0045] At this time, FIG. 2(a) is a drawing showing a gradient structure formed in the longitudinal direction and downward direction of the width of the rotor blade body (100), and FIG. 2(b) is a drawing showing a gradient structure formed in both the longitudinal direction and the width of the rotor blade body (100). When a gradient structure is formed in both directions, etching does not occur at the end of the rotor blade body (100), so it can be confirmed that the pattern portion (200) can be formed more stably than when a gradient structure is formed in one direction.

[0046] By means of the pattern part (200) formed with the above-mentioned gradient structure, the rotor blade body (100) is not damaged by pressure and external forces due to rotation even when rotating at high speed, thereby ultimately ensuring the flight stability of the unmanned aerial vehicle.

[0047] In addition, as shown in FIG. 4, when a pattern portion (200') is formed on the rotor blade body (100) and protrudes outward to a certain height and is formed in a raised shape, the pattern portion (200') is formed in a gradient structure in which the height decreases as it approaches the edge of the rotor blade body (100). This prevents the edge of the rotor blade body (100) from being damaged by resistance to air generated during loading or rotation on the thin airfoil structure at the edge, thereby ensuring the flight stability of the unmanned aerial vehicle.

[0048] At this time, FIG. 4(a) is a drawing showing a gradient structure formed in the longitudinal direction and downward direction of the width of the rotor blade body (100), and FIG. 4(b) is a drawing showing a gradient structure formed in both the longitudinal direction and the width of the rotor blade body (100). When a gradient structure is formed in both directions, it can be confirmed that the embossed pattern portion (200') formed on the surface of the rotor blade body (100) can be formed more stably.

[0049] In other words, the pattern portion (200, 200') is not limited to being formed by being indented into the surface of the rotor blade body (100), and in some cases, it may be formed in relief so as to protrude outwardly from the surface of the rotor blade body (100). By forming a gradient structure in which the diameter (meaning depth in the case of indentation and height in the case of relief) decreases in correspondence with the shape of an airfoil that becomes thinner toward the edge, the noise reduction efficiency can be maximized, and at the same time, the stability of the rotor blade body (100) and furthermore, the flight stability of the unmanned aerial vehicle can be secured.

[0050] The above-mentioned gradient structure may be formed in one direction or both directions based on the longitudinal direction of the rotor blade body (100), or in one direction or both directions based on the width direction of the rotor blade body (100), and may be formed in a combination where both the longitudinal direction reference and the width direction reference of the rotor blade body (100) are applied.

[0051] That is, the gradient structure can be formed in at least one of four directions, including the longitudinal and width directions of the rotor blade body (100), and this can be more easily understood by referring to FIG. 5.

[0052] For example, FIG. 5(a) is an example illustration showing a pattern section (200) formed on the rotor blade body (100) without a gradient structure applied; FIG. 5(b) is an example illustration showing a pattern section (200) with a gradient structure applied in the longitudinal direction of the rotor blade body (100); FIG. 5(c) is an example illustration showing a pattern section (200) with a gradient structure applied in one direction (lower side) of the longitudinal direction and width of the rotor blade body (100); and FIG. 5(d) is an example illustration showing a pattern section (200) with a gradient structure applied in both directions of the longitudinal direction and width of the rotor blade body (100).

[0053] Referring to FIG. 5(a), even if a pattern portion (200) is formed on the rotor blade body (100), if a gradient structure is not applied, excessive etching (over-patterning) occurs at the end according to the airfoil of the rotor blade body (100), which increases the possibility of damage to the rotor blade body (100) due to pressure received during rotation or small external impacts, as well as the stability, noise reduction efficiency, and thrust generation efficiency of the rotor blade (A).

[0054] In addition, even if a gradient structure is applied to the rotor blade body (100), as shown in FIG. 5 (b), if it is applied only in the longitudinal direction of the rotor blade body (100), excessive etching (over-patterning) still occurs in the width direction, and thus the problem described above may still occur.

[0055] At this time, FIG. 5 (c) and (d) represent a case where a gradient structure is applied in the width direction as well as in the length direction of the rotor blade body (100). As shown in FIG. 5 (c), when a gradient structure is applied in one direction based on the length and width directions of the rotor blade body (100), more specifically in the downward direction of the width, excessive etching (over-patterning) as shown in FIG. 5 (a) and (b) does not occur, but some etching (over-patterning) occurs at the upper part of the rotor blade body (100) according to the airfoil of the rotor blade body (100), so it is difficult to consider that the above-mentioned problem has been completely resolved.

[0056] At this time, in order to completely prevent the occurrence of etching on the rotor blade body (100) and to maximize the stability of the rotor blade (A), as well as the noise reduction efficiency and thrust generation efficiency, it is most desirable to apply a gradient structure in both the longitudinal direction and the width direction of the rotor blade body (100), as shown in (d) of FIG. 5.

[0057] The process of forming the pattern portion (200) with the gradient structure applied to the rotor blade body (100) as described above can be more easily understood by referring to FIG. 6, which is an example diagram showing the pattern portion (200) having a diameter of 1 mm.

[0058] As shown in FIG. 6 (a), by planning and applying a gradient structure pattern (surface pattern for texturing) of a standard corresponding to a basic type, that is, a conventional rotor blade (blade surface), a rotor blade (textured blade surface) having a pattern part (200) formed with a gradient structure can be formed.

[0059] At this time, FIG. 6(b) shows an initial pattern section (200) to which a gradient structure is not applied, FIG. 6(d) shows a gradient structure formed in one direction based on the length direction of the rotor blade body (100), FIG. 6(e) shows a gradient structure formed in one direction based on the width direction of the rotor blade body (100), FIG. 6(f) shows the gradient structures of (d) and (e) superimposed, and FIG. 6(g) shows a pattern section (200) formed on the rotor blade body (100) with the gradient structure of (f) applied.

[0060] At this time, Fig. 6(c) is a drawing showing an error phenomenon that occurs when applying a gradient structure, namely, an over-patterning that occurs on the rotor blade body (100), and a calculation formula to be described later may be applied to prevent such over-patterning.

[0061] In addition, FIG. 7 is an example diagram showing a process of forming a pattern part (200) having a gradient structure in both directions on the rotor blade body (100) by improving the gradient structure in one direction shown in FIG. 6 described above.

[0062] According to one embodiment of the present invention, in order to generate the pattern portion (200) corresponding to the blade surface shape, a Hermite cubic surface formula as shown in the formula below can be applied.

[0063]

[0064] Here, u and v are parameters for the horizontal and vertical directions, respectively, that is, the length and width directions of the rotor blade body (100), and have values ​​between 0 and 1.

[0065] P (u,v) is the position vector, C ij represents the coefficient tensor.

[0066] In addition, while the pattern diameter is set uniformly prior to the application of the gradient, the gradient must reduce the pattern diameter to accommodate thickness variations according to the surface shape.

[0067] To this end, the formula for the gradient structure expressed as a cubic function of parameters corresponding to the blade surface is,

[0068]

[0069]

[0070] A formula that can be applied and represents a gradient structure in both directions by performing a multiplication operation between the two gradient functions above is,

[0071]

[0072] It can be achieved by, where n is the number of gradient functions for each direction, represents the weight factor of the gradient structure.

[0073] According to one embodiment of the present invention, the pattern having the pattern part (200) is not limited to a square grid pattern structure with a grid shape as described above, and various pattern structures such as a dot pattern structure, a triangular pattern structure, and a diamond pattern structure may be applied. However, in the case of this embodiment, it is most preferable to have a square grid pattern structure to maximize noise reduction efficiency. This can be more easily understood by referring to the graph showing the noise reduction effect when each of the various pattern structures including the square grid pattern structure shown in FIG. 8 is applied, and the graph comparing the noise and thrust generated when each of the various pattern structures including the square grid pattern structure shown in FIG. 9 is applied.

[0074] At this time, in Fig. 9 The square grid pattern structure refers to a pattern structure in which a gradient structure is applied in one direction (outer diameter direction) based on the length direction of the rotor blade body (100) and in one direction (lower direction) based on the width direction. [It] refers to a pattern structure in which a gradient structure is applied among square grid pattern structures, consisting of one direction (outer diameter direction) based on the length direction of the rotor blade body (100) and two directions (upper and lower sides) based on the width direction, and as shown in FIG. 9, on the rotor blade body (100) When the pattern structure is applied, the noise generated is reduced and the thrust is improved compared to the basic structure (Plain) in which the pattern part is not formed, so it can be interpreted that the noise and thrust characteristics of the rotor blade (A) can be simultaneously satisfied.

[0075] In addition, the pattern portion (200) is formed on the surface of the rotor blade body (100), but is not limited to the upper surface of the rotor blade body (100). Depending on the case, it may be applied and formed on both the upper and lower surfaces. It should be noted that the pattern portion (200) may be formed as an intaglio on the upper surface and a relief on the lower surface of the rotor blade body (100), or conversely, as a relief on the upper surface and an intaglio on the lower surface, or formed as an intaglio or relief on both the upper and lower surfaces.

[0076] By applying the rotor blade (A) having the rotor blade body (100) having the pattern portion (200) having the structure described above formed on its surface, the mold is modified so that the fine pattern of the pattern portion (200) is formed to match the specifications of the existing blade without having to replace the entire mold for mass-producing the existing unmanned aerial vehicle blade, thereby minimizing the economic burden and maximizing the noise reduction efficiency of the unmanned aerial vehicle, and ensuring stable propulsion of the unmanned aerial vehicle.

[0078] As described above, preferred embodiments according to the present invention have been examined. It is obvious to those skilled in the art that, in addition to the embodiments described above, the present invention may be embodied in other specific forms without departing from the spirit or scope thereof. Therefore, the embodiments described above should be regarded as illustrative rather than restrictive, and accordingly, the present invention is not limited to the description above but may be modified within the scope of the appended claims and their equivalents. Explanation of the symbols

[0080] 100: Rotor blade body 200 : Pattern section (engraving) 200' : Pattern section (embossing) A: Rotor blade

Claims

Claim 1 delete Claim 2 A rotor blade body provided in an unmanned aerial vehicle, which rotates around a coupling part to generate thrust necessary for the flight of the unmanned aerial vehicle; and a pattern part formed on the surface of the rotor blade body to reduce noise generated as the rotor blade body rotates; wherein the pattern part is formed with a repeating pattern structure spaced apart from each other based on the longitudinal and width directions of the rotor blade body, thereby dispersing the flow of vortices generated around the rotor blade body to reduce noise caused by the rotation of the rotor blade body, and is formed on the surface of the rotor blade body as either an intaglio through a subtraction operation or a relief through an addition operation, and is formed with a gradation structure in which the formation depth or height of the pattern part decreases towards the edge of the rotor blade body to correspond to the airfoil shape of the rotor blade body, which becomes thinner towards the edge, and wherein the gradation structure is applied in both the longitudinal and width directions of the rotor blade body, and the rotor blade has a surface micro-pattern formed thereon. Claim 3 In paragraph 2, the pattern portion is formed with a square grid pattern structure in the shape of a grid, and the rotor blade has a surface micro-pattern formed therein that allows for the adjustment of mutually spaced intervals based on the length direction and width direction of the rotor blade body. Claim 4 delete Claim 5 delete

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