Inertial force generating device and method for applying an inertial force to a blade

Abstract

Provided are an inertial force generating device and a method of applying an inertial force to a blade. The inertial force generating device includes an inertial force applying portion for applying an inertial force to a position at a distance of 20% to 50% of the total length of the blade from the root of the blade, and an inertial force supplying portion for supplying the inertial force applying portion with an inertial force of a desired magnitude using a mass portion, wherein the mass portion is physically separated from the blade. According to the present invention, an inertial force can be generated in the blade even without directly connecting the mass portion to the blade, and in a blade fatigue test, the heaviest mass portion can be connected, and the inertial force generating device can be connected to a position on the blade that is not damaged by itself, thereby having the effect of maximizing the suppression of damage to the blade during the test while performing the blade fatigue test with high reliability.

Description

Technical Field

[0001] This invention relates to an inertial force generating device, and more particularly to an inertial force generating device for applying inertial force to, for example, wind turbine blades, and a method for applying inertial force to the blades using the device. Background Technology

[0002] The blades used in wind power generation are used to obtain the rotational force required to rotate the generator that produces electricity, while the blades used in rotary-wing aircraft are used to generate the lift, thrust, and control force required for the aircraft to fly.

[0003] The rotation of the blades used in wind power generation causes changes in the aerodynamic distribution around the blades, which generates continuous bending loads on the blade structure.

[0004] For the safe operation of the blades, fatigue life verification is required based on fatigue bending loads occurring over a 20-year period. As fatigue testing methods, there are resonance testing methods that utilize the blade's natural frequency. Resonance testing methods include on-board excitation methods, which apply excitation energy by directly mounting an exciter on the blade, and external excitation methods, which apply excitation energy to the blade by connecting / mounting an exciter to the ground.

[0005] When fatigue testing is conducted using resonance, the vibration mode of the blade is controlled to the desired shape to achieve the target load. To control this vibration mode, mass units are connected and adjusted at multiple locations. However, these attached mass units generate additional loads on the blade due to gravity, potentially damaging it under excessive environmental conditions.

[0006] For example, Korean Patent No. 10-1401082B1 relates to a technology for a device to reduce air resistance in blade fatigue testing. Specifically, it provides a device for reducing air resistance in blade fatigue testing, characterized by including an air resistance reduction means configured in a closed-loop cross-sectional shape, with the wind turbine blade passing through its interior and remaining separated from both sides of the blade. This reduces air resistance occurring during fatigue testing. A support portion is provided inside the air resistance reduction means, forming a filling space so that a portion of the air resistance reduction means's shape is curved. However, the weight provided by this technology to obtain the desired amplitude itself places an additional load on the test blade, potentially damaging it when evaluating the blade under excessive conditions.

[0007] Therefore, the inventors of this invention have studied a device and method that can induce fatigue in the blade under test without causing damage, and can generate inertial force on the blade without the weight of the mass part acting on the blade during the fatigue test, thus completing this invention. Summary of the Invention

[0008] Technical issues

[0009] The purpose of this invention is to provide an inertial force generating device.

[0010] Another object of the present invention is to provide a method for applying inertial force to a blade.

[0011] Technical solution

[0012] Therefore, the present invention provides an inertial force generating device, comprising:

[0013] An inertial force applying section, said inertial force applying section for applying an inertial force to a position at a distance of 20% to 50% of the total blade length from the blade root; and

[0014] An inertial force supply unit is used to supply an inertial force of a required magnitude to the inertial force application unit using a mass unit;

[0015] The mass unit and the blade are physically isolated from each other.

[0016] In addition, the present invention provides a method for applying an inertial force to a blade, comprising:

[0017] The step of installing the inertial force generating device at a distance of 20% to 50% of the total blade length from the blade root; and

[0018] The step of applying an inertial force to the blade via the inertial force generating device during the vibration of the blade due to the operation of the exciter.

[0019] Invention Effects

[0020] According to the present invention, even without directly connecting the mass part to the blade, the blade can generate inertial force. Therefore, during the blade fatigue test, the heaviest mass part can be connected, and the inertial force generating device can be connected to a location where the blade will not be damaged by itself. This has the effect of suppressing blade damage during the test to the maximum extent while performing the blade fatigue test with high reliability.

[0021] In addition, by utilizing the length ratio and tooth ratio of the device, the size of the required mass can be effectively reduced, thereby simplifying the preparation of the mass required for the experiment. Attached Figure Description

[0022] Figure 1 This is a schematic diagram illustrating an embodiment of the inertial force generating device of the present invention.

[0023] Figure 2 This is a schematic diagram illustrating an inertial force generating device according to another embodiment of the present invention.

[0024] Figure 3 This is a schematic diagram illustrating the structure of an inertial force supply unit that can be used in an exemplary embodiment of the present invention.

[0025] Figure 4 It is a graph showing the relationship between the length of the blade under test and the inertial force required for the test.

[0026] Figure 5 This is a simulation graph showing the torque results of a device applied by an inertial force application unit to apply an inertial force at a location less than 20% of the total blade length from the blade root.

[0027] Figure 6 This is a simulation graph showing the torque results of a device used to apply inertial forces to a location 20% to 50% of the total blade length at a distance from the blade root.

[0028] Figure 7 A simulation graph showing the torque results of the device applied by the inertial force application unit for applying inertial force to a position at a distance greater than 50% of the total blade length from the blade root. Detailed Implementation

[0029] In this invention, "mass body" and "mass unit" are used to mean the same thing.

[0030] This invention provides an inertial force generating device. More specifically, in fatigue tests of blades used in wind power plants, for example, the known technique involves connecting a mass to the blade to generate inertial force. The device of this invention provides an inertial force generating device for generating inertial force on a blade during a blade fatigue test without directly connecting a mass to the blade.

[0031] More specifically, the present invention provides an inertial force generating device, comprising:

[0032] An inertial force applying section, said inertial force applying section for applying an inertial force to a position at a distance of 20% to 50% of the total blade length from the blade root; and

[0033] An inertial force supply unit is used to supply an inertial force of a required magnitude to the inertial force application unit using a mass unit;

[0034] The mass unit and the blade are physically isolated from each other.

[0035] The inertial force generating device of the present invention will now be described in detail according to its components.

[0036] The inertial force generating device of the present invention includes an inertial force applying part, which is used to apply an inertial force to a position at a distance of 20% to 50% of the total length of the blade root.

[0037] In this invention, the "root" of a blade is defined as the end of the blade that connects to the hub of the wind turbine. The "tip" is defined as the end of the blade furthest from the center of the wind turbine.

[0038] Typically, during fatigue testing of blades used in wind power plants, mass units of appropriate weight are placed at different distances from the root to the tip. An exciter is placed at one of the locations where these mass units are placed, and the blade is excited at the same frequency as its natural frequency to perform a resonant fatigue test.

[0039] At this point, the method of applying vibration to the blade can be categorized into two types based on the direction of vibration application: applying vibration in the flap direction and applying vibration in the edge direction. In this invention, "flap direction" refers to the normal direction of the blade surface, and "edge direction" refers to the direction perpendicular to the normal direction of the blade surface, i.e., the "edge" direction of the blade.

[0040] To perform fatigue testing on blades, inertial forces are required. Therefore, a mass is typically attached to the blade. When vibration is applied to the blade, the amplitude is smaller near the root and larger further away from the root and closer to the blade tip. Therefore, considering this, a heavier mass is attached near the blade root, and a lighter mass is attached further away from the root. However, considering the amplitude, when performing fatigue testing with a heavier mass near the blade root, there is a risk that the blade may be damaged during the fatigue test, or that fatigue may accumulate due to the test itself.

[0041] To solve this problem, the present invention does not directly connect the mass part to the blade, but physically isolates the mass part from the blade and includes an inertial force application part for applying an inertial force to a position at a distance of 20% to 50% of the total blade length from the blade root, thereby applying an inertial force to the blade.

[0042] The total inertial force required for fatigue testing is represented by the sum of the blade's own weight and the installed mass. The installed mass is determined to achieve the target inertial moment that allows the blade to undergo appropriate fatigue testing. At this point, to achieve the target inertial moment, such as... Figure 4As shown in the diagram, a predetermined inertial force needs to be applied relative to the blade length. However, the inertial force caused by the blade's own weight is triangular in shape, and the remaining insufficient force needs to be obtained by adding an additional mass. In this case, the inertial force obtained by adding the mass is also triangular in shape. The most efficient location for applying the inertial force is the center of the triangle, that is, a position between 20% and 50% of the total blade length from the blade root. This phenomenon varies depending on the blade type or the fatigue test in the flap / edge direction, but adding the mass at 20% to 50% is more effective. If the distance from the blade root to the added mass is less than 20% of the total blade length, there is a problem of needing to set an extremely large weight; in cases exceeding 50%, it will be impossible to set it correctly.

[0043] In the actual design, the mass section added to the blade needs to accommodate the largest mass component in that area. Therefore, a separate design and fabrication of the additional mass section is required for the structure to be placed on the blade, incurring additional costs and time, and necessitating measures to ensure structural reliability. Furthermore, this large mass section requires approximately 5 to 30 tons, which is excessively heavy for the blade's structural strength and for preparation for testing and installation.

[0044] Furthermore, the inertial force applying unit of the present invention includes an inertial force supply unit for supplying an inertial force of the required magnitude using a mass unit. Similar to the prior art, in the present invention, the inertial force applied to the blade is generated by the mass unit and supplied to the blade. However, as described above, in the present invention, the mass unit and the blade are physically isolated, thus solving the problem of blade damage or fatigue accumulation due to the weight of the mass unit itself. In this case, the mass unit included in the inertial force supply unit of the present invention can supply the inertial force generated by the mass unit to the inertial force applying unit through various connection means.

[0045] At this time, the inertial force application unit of the inertial force generating device of the present invention can be configured to apply the inertial force supplied by the inertial force supply unit to the flap direction of the blade. The flap direction, as described above, is the normal direction of the blade surface. For example, when the blade surface is configured to face the sky, the vertical direction is defined as the flap direction of the blade. Typically, when testing the fatigue of a blade, a vibrator can be used to vibrate the blade along the flap direction. In this case, the inertial force application unit of the inertial force generating device of the present invention is configured to apply the inertial force supplied by the supply unit to the flap direction of the blade, providing an inertial force in the flap direction to the blade instead of the mass part directly connected to the blade in the blade flap direction fatigue test.

[0046] Alternatively, the inertial force application unit of the inertial force generating device of the present invention can be configured to apply the inertial force supplied by the inertial force supply unit towards the edge direction of the blade. The edge direction, as described above, is the direction perpendicular to the normal direction of the blade surface. For example, when the blade surface is configured to face the sky, the left-right direction is defined as the edge direction of the blade. Typically, when testing blade fatigue, a vibrator can be used to vibrate the blade along the insulation direction. In this case, the inertial force application unit of the inertial force generating device of the present invention is configured to apply the inertial force supplied by the supply unit towards the edge direction of the blade, providing an edge-direction inertial force to the blade instead of the mass portion directly connected to the blade in the edge-direction fatigue test.

[0047] Furthermore, the inertial force applying unit of the inertial force generating device of the present invention can also be configured to apply the inertial force supplied by the inertial force supply unit to the flap direction and the edge direction of the blade. That is, when testing the fatigue of the blade in both the flap direction and the edge direction at the same time, in the inertial force generating device of the present invention, the inertial force applying unit can be configured to apply inertial forces to the flap direction and the edge direction of the blade respectively.

[0048] On the other hand, in terms of applying the inertial force generated by the mass unit and supplied by the inertial force supply unit to the blade by means of the inertial force application unit, the inertial force generating device of the present invention preferably further includes a connecting part for connecting to the blade in order to fix the inertial force application part to the blade and effectively apply the inertial force to the blade. The inertial force application part of the present invention is fixedly connected to the blade by the connecting part it includes, and therefore has the advantage of being able to effectively and stably apply the generated inertial force to the blade.

[0049] On the other hand, the inertial force supply unit in the inertial force generating device of the present invention may have a lever structure, one end of the inertial force applying unit may be disposed at one end of the lever structure, and the mass unit may be disposed at the other end of the lever structure. Specifically, the inertial force supply unit of the present invention has a lever structure having one end and another end. The inertial force applying unit is used to apply inertial force to the blade. The end of the inertial force applying unit located on the opposite side of the end connected to the blade may be disposed at one end of the inertial force supply unit having the lever structure, and the mass unit that generates the inertial force may be disposed at the other end of the inertial force supply unit having the lever structure. By means of the mass unit disposed at the other end of the inertial force supply unit, the lever structure of the inertial force supply unit is moved, thereby supplying inertial force to the inertial force applying unit disposed at the other end of the inertial force supply unit. The supplied inertial force is applied to the blade through the inertial force applying unit.

[0050] Furthermore, in the inertial force generating device of the present invention, when the inertial force supply unit has the lever structure described above, the weight of the mass unit used to supply the required inertial force can be determined based on the ratio of the distance from one end of the lever structure disposed at the inertial force application unit to the lever support unit to the distance from the other end of the lever structure disposed at the mass unit to the lever support unit. By equipping this structure, it is possible to generate the required inertial force using a smaller mass unit.

[0051] Furthermore, in the inertial force generating device of the present invention, the mass portion of the inertial force supply unit moves horizontally. The inertial force supply unit may include a rack for the mass portion, a rack for the blade, and planetary gears connected to all of these racks. By adjusting the tooth ratio between the rack for the mass portion and the rack for the blade, the required inertial force is supplied by the mass portion. With the structure formed as described above, the mass portion only provides inertial force relative to the edge direction of the blade, ensuring that the blade remains completely undeformed in the vertical direction. This avoids the problem of unnecessary fatigue accumulation or damage to the blade, and is therefore more advantageous. Another advantage is that adjusting the tooth ratio between the rack for the mass portion (i.e., the rack connected to the mass portion) and the rack for the blade (i.e., the rack connected to the blade) easily adjusts the required inertial force supplied to the blade.

[0052] This invention provides a method for applying inertial force to a blade.

[0053] Typically, when performing fatigue tests on blades, especially those used in wind turbines, the blade fatigue test is conducted by vibrating it using a vibrator mounted on the blade and connected to multiple mass units at various locations on the blade surface. The fatigue test can be performed in the defined flap and edge directions, or simultaneously in both directions. In the original method, to generate inertial forces on the blade during fatigue testing, mass units are connected to multiple locations on the blade surface. However, due to the weight of these mass units, fatigue can accumulate on the tested blade, potentially causing damage. Especially during blade vibration, the amplitude is smaller near the blade root and larger further away. Correspondingly, the presence of heavier mass units near the blade root exacerbates this problem.

[0054] To address this problem, the present invention provides a method for applying an inertial force to a blade, comprising:

[0055] The step of installing the inertial force generating device at a distance of 20% to 50% of the total blade length from the blade root; and

[0056] The step of applying an inertial force to the blade via the inertial force generating device during the vibration of the blade due to the operation of the exciter.

[0057] *85 The method for applying inertial force to a blade according to the present invention is described in detail below step by step.

[0058] The method of applying inertial force to a blade according to the present invention includes the step of installing the inertial force generating device of the present invention at a position at a distance of 20% to 50% of the total length of the blade from the root of the blade.

[0059] The total inertial force required for fatigue testing is represented by the sum of the blade's own weight and the installed mass. The installed mass is determined to achieve the target inertial moment that allows the blade to undergo appropriate fatigue testing. At this point, to achieve the target inertial moment, such as... Figure 4 As shown in the diagram, a predetermined inertial force needs to be applied relative to the blade length. However, the inertial force caused by the blade's own weight is triangular in shape, and the remaining insufficient force needs to be obtained by adding a mass. In this case, the inertial force obtained by adding the mass is also triangular in shape. The most efficient location for applying the inertial force is the center of the triangle, that is, a position between 20% and 50% of the total blade length from the blade root. This phenomenon varies depending on the blade type or the fatigue test in the flap / edge direction, but adding the mass at 20% to 50% is more effective. If the distance from the blade root to the added mass is less than 20% of the total blade length, there is a problem of needing to set an extremely large weight; in cases exceeding 50%, it will be impossible to set it correctly.

[0060] In the actual design, the mass section added to the blade needs to accommodate the largest amount of mass in this area. Therefore, a separate design and fabrication of the additional mass section is required for the structure to house it on the blade, incurring additional costs and time, and necessitating measures to ensure structural reliability. Furthermore, this large mass section requires approximately 5 to 30 tons, which is excessively heavy for the blade's structural strength.

[0061] In this step, the inertial force applying part in the inertial force generating device of the present invention is connected to the blade, or the inertial force applying part can be stably connected to the blade using another connecting part.

[0062] The method for applying inertial force to a blade according to the present invention includes the step of applying an inertial force to the blade via the inertial force generating device during the blade's vibration caused by the operation of the exciter. In the prior art, mass units are connected to multiple locations on the blade, and inertial forces are applied to the blade via the corresponding mass units during blade vibration. In this case, due to the weight of the mass units themselves, there is a problem that the blade under test may accumulate fatigue or the blade may be damaged. However, in the method of the present invention, an inertial force generating device that is physically isolated from the blade applies an inertial force to the blade during blade vibration, thereby solving the problems of the prior art method described above.

[0063] At this point, the step of applying inertial force to the blade according to the present invention can be to apply the inertial force in the flap direction of the blade. Alternatively, the step of applying inertial force to the blade according to the present invention can also be to apply the inertial force in the edge direction of the blade. As described above, the fatigue test of the blade can be performed by using a vibrator to make the blade vibrate in the flap direction or in the edge direction, and furthermore, the fatigue test can be performed simultaneously by vibrating in both the flap direction and the edge direction. The inertial force generating device used in the method of the present invention can apply inertial force in both the flap direction and the edge direction of the blade, thus having the advantage of being able to apply inertial force in all directions of blade fatigue testing.

[0064] In the prior art, a mass part is connected to the blade itself in order to apply inertial force to the blade during blade fatigue testing. As mentioned above, there is a problem that the mass part connected to generate inertial force may damage the blade under test. The method of the present invention applies the inertial force generated by the mass part which is physically isolated from the blade to the blade, thereby having the advantage of solving the problem that occurs in the prior art.

[0065] On the other hand, the inertial force supply unit in the inertial force generating device of the present invention has a lever structure, one end of the inertial force applying unit can be disposed at one end of the lever structure, and the mass part can be disposed at the other end of the lever structure. Specifically, the inertial force supply unit of the present invention has a lever structure having one end and another end. The inertial force applying unit is used to apply inertial force to the blade. The end of the inertial force applying unit located on the opposite side of the end connected to the blade can be disposed at one end of the inertial force supply unit having the lever structure, and the mass part that generates the inertial force can be disposed at the other end of the inertial force supply unit having the lever structure. By means of the mass part disposed at the other end of the inertial force supply unit, the lever structure of the inertial force supply unit is moved, thereby supplying inertial force to the inertial force applying unit disposed at the other end of the inertial force supply unit. The supplied inertial force is applied to the blade through the inertial force applying unit.

[0066] Furthermore, in the method for applying inertial force according to the present invention, when the inertial force supply unit has the lever structure as described above, the weight of the mass unit used to supply the required inertial force can be determined based on the ratio of the distance from one end of the lever structure disposed at one end of the inertial force application unit to the lever support unit to the distance from the other end of the lever structure disposed at the mass unit to the lever support unit. By equipping this structure, it has the effect of generating the required inertial force in a more convenient manner.

[0067] Furthermore, in the method of applying inertial force according to the present invention, the mass portion of the inertial force supply unit moves horizontally. The inertial force supply unit may include a rack for the mass portion, a rack for the blade, and planetary gears connected to all of these racks. By adjusting the tooth ratio between the rack for the mass portion and the rack for the blade, the required inertial force is supplied by the mass portion. With the structure formed as described above, the mass portion only provides inertial force relative to the edge direction of the blade, ensuring that the blade remains completely undeformed in the vertical direction. This avoids the problem of unnecessary accumulation of fatigue or damage to the blade, and is therefore more advantageous. Another advantage is that the required inertial force supplied to the blade can be easily adjusted by adjusting the tooth ratio between the rack for the mass portion (i.e., the rack connected to the mass portion) and the rack for the blade (i.e., the rack connected to the blade).

[0068] Furthermore, the present invention provides a method for fatigue testing of a blade, wherein an inertial force is applied to the blade using the method described above when the blade is moved by a vibrator. As described above, in the conventional blade fatigue testing method, a mass is connected to multiple locations on the blade, and a vibrator is installed at one of these locations to vibrate the blade, thereby performing a fatigue test. The vibration direction can be the flap direction, the edge direction, or both of these directions, and the blade fatigue accumulation during vibration in that direction is confirmed. However, this method directly connects the mass to the blade to generate the inertial force. Especially during vibration, the amplitude is smaller near the blade root and larger further away. Therefore, a heavier mass needs to be connected near the blade root, resulting in fatigue accumulation on the tested blade due to the mass itself, and potentially even blade damage. The present invention, as described above, solves the problems of the conventional technology by physically isolating the mass that generates the inertial force from the blade. Furthermore, by utilizing the inertial force generating device of the present invention, the inertial force generated by the mass part can be applied to the flap direction of the blade or to the edge direction, and thus the inertial force can be applied to both the flap direction and the edge direction, thereby having the advantage of being applicable to blade fatigue tests in all situations.

[0069] The inertial force generating device, the method for applying inertial force, and the blade fatigue testing method of the present invention will be described in more detail below with reference to the accompanying drawings. The following description is intended only to describe the invention in more detail and is not intended to limit the scope of the invention based on the following description, specific configuration, or shape.

[0070] Figure 1 A specific example of the inertial force generating device 100 of the present invention is shown, exemplarily illustrating an example of applying an inertial force relative to blade B in the flap direction F. From Figure 1It is understood that the inertial force generating device 100 of the present invention is positioned at a distance from the root of blade B that is 20% to 50% of the total length l of blade B. More specifically, the inertial force applying part 110 of the inertial force generating device 100 is positioned at a position corresponding to 20% to 50% of the total length l of blade B. At this time, it can be confirmed that the connecting part 111 is additionally provided for the inertial force applying part 110 to more effectively connect with blade B. The inertial force supply part 120 in the inertial force generating device 100 is exemplary formed as a lever structure, with one end of the inertial force applying part 110 disposed at one end of the lever, and a mass part 121 for generating inertial force disposed at the other end of the lever. At this time, by adjusting the ratio of the distance a from the end where the inertial force applying part 110 is disposed to the fulcrum 122 to the distance b from the other end of the lever structure where the mass part 121 is disposed to the fulcrum 122, the degree of the supplied inertial force can be adjusted, or the weight of the mass part 121 used can be adjusted. During blade fatigue testing, if the blade is vibrated using an exciter (not shown), the inertial force generated by the mass unit 121 is supplied to the inertial force application unit 110 through the inertial force supply unit 120. The inertial force application unit 110 applies the inertial force to the blade B, replacing the original mass unit that is directly connected to the blade and supplies the inertial force.

[0071] Figure 2 Another specific example of the inertial force generating device 200 of the present invention is shown, exemplarily illustrating an example of applying an inertial force relative to the blade B in the edge direction E. From Figure 2 It is understood that the inertial force generating device 200 of the present invention is positioned at a distance from the root of blade B that is 20% to 50% of the total length l of blade B. More specifically, the inertial force applying part 210 of the inertial force generating device 200 is positioned at a position corresponding to 20% to 50% of the total length l of blade B. At this time, it can be confirmed that the inertial force applying part 210 is additionally equipped with a connecting part 211 for more effective connection with blade B. The inertial force supply part 220 in the inertial force generating device 200 is exemplarily formed with a combination structure of rack and pinion and planetary gear. Specifically, it includes a rack connected to the mass part 221, a rack connected to the blade, more specifically, a rack connected to the inertial force applying part 210 connected to the blade, and planetary gears connected to all these racks. The inertial force applied to the blade can be adjusted according to the ratio of the number of teeth of the rack connected to the mass part 221 to the number of teeth of the rack connected to the inertial force applying part 210.

[0072] Figure 3 A more specific description Figure 2 A diagram of the inertial force supply section of the structure shown. According to... Figure 3 It can be confirmed that the mass-side rack 222 and the blade-side rack 223 connected to the mass section 221 are both connected to the planetary gear 224. With the help of this structure, the inertial force applied to the blade can be adjusted by adjusting the gear ratio.

[0073] The invention is described in more detail below through experimental examples. These examples are intended to illustrate the invention only and are not intended to limit the scope of the claims made herein.

[0074] <Experimental Example>

[0075] To derive the torque required for blade fatigue testing using the inertial force generator of this invention, mode shape analysis was simulated using the commonly used structural analysis program ABAQUS while changing the position of the inertial force application point. The results are shown below. Figure 5 , Figure 6 and Figure 7 middle.

[0076] In the simulation, in order to achieve the torque distribution relative to the length direction required by the experiment ( Figure 5 , Figure 6 and Figure 7 By configuring an appropriate weight according to the blade's mode shape, the torque distribution achieved under resonant fatigue test conditions is calculated. Figure 5 , Figure 6 and Figure 7 (B) The mass body was selected based on the condition that the ratio does not exceed 5%. Furthermore, when selecting the mass body, if a mass body of 10 tons or more is used, it is difficult to install and operate on site using cranes or the like, and it may also cause damage to the blade surface. Therefore, it is assumed that an inertia generating device will be used.

[0077] contrast Figure 5 and Figure 6 When the inertial force application unit is positioned at a distance from the blade root that is more than 0% but less than 20% of the total blade length, the desired setting target (B / A ratio) can be achieved, similar to when the inertial force application unit is positioned at a distance from the blade root that is 20% to 50% of the total blade length (as in this application invention). However, even if an inertial generating device is used for this purpose, there is a problem that excessive weight needs to be installed on the inertial force application unit, which is impractical in terms of the design, operation, and manufacturing of real inertial generating devices. Furthermore, from... Figure 7 It can be confirmed that when the inertial force application part is positioned at a distance from the blade root exceeding 50% of the total blade length, the desired setup target (B / A ratio) cannot be achieved at all.

[0078] Figure Labels

[0079] B: Blade

[0080] l: Blade length

[0081] F: Blade flap direction

[0082] E: Blade edge direction

[0083] a: The distance from the portion disposed at one end of the inertial force application part to the support part.

[0084] b: Distance from the part supplied by the quality department to the support unit

[0085] 100, 200: Inertial force generating device

[0086] 110, 210: Inertial force application part

[0087] 111, 211: Connecting parts

[0088] 120, 220: Inertial Force Supply Department

[0089] 121, 221: Quality Department

[0090] 122: Support section

[0091] 222: Side rack of the quality department

[0092] 223: Blade side rack

[0093] 224: Planetary Gear

Claims

1. An inertial force generating device, characterized in that, include: An inertial force applying part is used to apply an inertial force to a position at a distance of 20% to 50% of the total blade length from the blade root; and An inertial force supply unit is used to supply an inertial force of a required magnitude to the inertial force application unit using a mass unit; The mass unit and the blade are physically isolated from each other, and The mass section of the inertial force supply unit moves horizontally. The inertial force supply unit includes a rack for the mass section, a rack for the blade, and planetary gears connected to all of these racks. The ratio of the number of teeth of the rack for the mass section to the number of teeth of the rack for the blade is adjusted to supply the required inertial force using the mass section.

2. The inertial force generating device according to claim 1, characterized in that, The inertial force applying part is configured to apply an inertial force in the flap direction of the blade.

3. The inertial force generating device according to claim 1, characterized in that, The inertial force application unit is configured to apply an inertial force toward the edge of the blade.

4. The inertial force generating device according to claim 1, characterized in that, The inertial force application part also includes a connection part for connecting with the blade.

5. A method for applying an inertial force to a blade, characterized in that, include: The step of installing the inertial force generating device of claim 1 at a distance of 20% to 50% of the total length of the blade from the root of the blade; and The step of applying an inertial force to the blade via the inertial force generating device during the vibration of the blade due to the operation of the exciter.

6. The method for applying inertial force to a blade according to claim 5, characterized in that, The step of applying inertial force to the blade is to apply inertial force in the direction of the blade's flap.

7. The method for applying inertial force to a blade according to claim 5, characterized in that, The step of applying inertial force to the blade is to apply inertial force in the direction of the blade edge.

8. The method for applying inertial force to a blade according to claim 5, characterized in that, The method of applying inertial force to the blade involves applying the inertial force generated by a mass portion that is physically isolated from the blade to the blade.

9. A fatigue testing method for blades, characterized in that, While the blade is moved using an exciter, an inertial force is applied to the blade using the method of claim 5.

10. The fatigue testing method for blades according to claim 9, characterized in that, The applied inertial force is applied in the direction of the blade flap, the blade edge, or both.

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