Blade high-order vibration mode acquisition method and system based on medium-low speed camera

Abstract

The invention provides a blade high-order vibration mode obtaining method based on a medium-low speed camera, and the method comprises the steps: determining a maximum deformation position in a shooting sample based on the shooting sample obtained by the medium-low speed camera; obtaining the displacement response of the maximum deformation position of the shot sample; determining a calculation sample, wherein the calculation sample is a corresponding shooting sample of which the displacement response is in a relatively large range; and obtaining a full-field displacement response corresponding to the calculation sample so as to determine the high-order vibration mode of the blade.

Description

Technical Field

[0001] This invention relates to the field of vibration measurement technology, and in particular to a method and system for obtaining higher-order vibration modes of blades based on a medium- and low-speed camera. Background Technology

[0002] The operation of the high-pressure compressor or turbine in an engine can induce higher-order modes of blade vibration. High-magnitude, high-frequency higher-order modes leading to high-cycle fatigue significantly increase the likelihood of blade cracking, thus jeopardizing engine operational safety. Therefore, obtaining the higher-order modal characteristics of blades is crucial for optimizing blade configuration and extending blade lifespan.

[0003] The higher natural frequencies of blades often exceed 1500Hz, and the mode shapes corresponding to their higher modes (hereinafter referred to as higher mode shapes) are very complex with a rich distribution of nodal lines. Single-point measurement only obtains the natural frequency of the test piece, which means that the modal results obtained by the blade finite element calculation cannot correspond to the test results. Moreover, there is a relatively dense modal distribution in the high-frequency state, so it is urgent to obtain the real blade mode shapes in order to make modal judgments and correct the results obtained by finite element analysis.

[0004] To obtain higher-order vibration modes of blades, existing technologies include: using accelerometers, but these sensors, due to their large added mass, can affect the blade's vibration pattern; using strain gauges, but this requires a large number of gauges, resulting in high manpower and resource costs; and using Doppler scanning laser vibrometers, while accurate, requires long scanning times and poses a risk of blade damage under high-frequency excitation. Currently, considering all factors, high-speed camera imaging is one of the optimal solutions for obtaining higher-order vibration modes of blades. High-speed cameras have high sampling frequencies, enabling better acquisition of higher-order vibration modes; however, high-speed cameras, including ultra-high-speed cameras, are not readily available through commercial channels due to technological limitations. However, medium- and low-speed cameras are gradually being domestically produced, and their acquisition is relatively easy. Therefore, obtaining higher-order vibration modes of engine blades using medium-speed cameras is of great significance for ensuring the safe operation of engines.

[0005] Therefore, this paper attempts to propose a method and system for obtaining higher-order vibration modes of blades based on a medium- and low-speed camera. Summary of the Invention

[0006] The purpose of this invention is at least to provide a method for obtaining higher-order vibration modes of engine blades based on a medium- and low-speed camera, which uses a medium- and low-speed camera to measure higher-order vibration modes of engine blades under high-frequency vibration conditions.

[0007] The following provides a brief overview of one or more aspects to offer a basic understanding of them. This overview is not an exhaustive summary of all conceived aspects, nor is it intended to identify key or decisive elements of all aspects, nor to define the scope of any or all aspects. Its sole purpose is to present some concepts of one or more aspects in a simplified form to prepare for the more detailed descriptions that follow.

[0008] One embodiment of the present invention provides a method for obtaining higher-order vibration modes of a blade based on a medium- and low-speed camera, comprising: determining the location of the maximum deformation in a large number of images obtained by the medium- and low-speed camera; obtaining the displacement response of the location of the maximum deformation in the images; determining a calculation sample, wherein the calculation sample is the corresponding image sample with a displacement response over a large range; and obtaining the full-field displacement response corresponding to the calculation sample to determine the higher-order vibration modes of the blade.

[0009] In some embodiments, a larger range includes 70% to 100% of the maximum displacement response value, wherein the maximum displacement response value refers to the maximum value of the displacement response corresponding to the position of maximum deformation among several captured samples.

[0010] In some embodiments, the number of shooting samples obtained by the medium-low speed camera is several, and the position of the maximum deformation in the shooting sample is determined based on any one of the several shooting samples.

[0011] In some embodiments, the full-field displacement response of the calculated samples is averaged to determine the higher-order vibration modes of the blade.

[0012] In some embodiments, the camera's exposure time is preset before obtaining the sample; the exposure time Δt is determined by the following formula:

[0013]

[0014] Among them, f e The vibration frequency is the frequency at which the blade responds to a fixed-frequency excitation.

[0015] One embodiment of the present invention provides a system for acquiring higher-order vibration modes of a blade based on a medium- and low-speed camera. The system includes a first determining module, a first obtaining module, a second determining module, and a second obtaining module. The first determining module is used to determine the location of maximum deformation in the captured samples obtained by the medium- and low-speed camera. The first obtaining module is used to obtain the displacement response of the location of maximum deformation in the captured samples. The second determining module is used to determine a calculation sample, which is a captured sample with a displacement response over a large range. The second obtaining module is used to obtain the full-field displacement response corresponding to the calculation sample to determine the higher-order vibration modes of the blade.

[0016] In some embodiments, the second determining module is used to determine the maximum displacement response value, wherein the maximum displacement response value refers to the maximum value of the displacement response corresponding to the maximum deformation position among a plurality of captured samples; the second determining module determines the captured samples whose displacement response is in the range of 70% to 100% of the maximum displacement response value as the calculation samples.

[0017] In some embodiments, the system further includes a preset module for presetting the camera's shooting frame rate and exposure time; the preset module determines the camera's maximum frame rate as the shooting frame rate; the preset module determines the exposure time Δt using the following formula:

[0018]

[0019] Among them, f e The vibration frequency is the frequency at which the blade responds to a fixed-frequency excitation.

[0020] One embodiment of the present invention also provides a device for acquiring higher-order vibration modes of blades based on a medium- and low-speed camera. The device includes a processing unit for executing the above-described method for acquiring higher-order vibration modes of blades based on a medium- and low-speed camera.

[0021] In some embodiments, the device includes a first camera and a second camera, configured for dual-target positioning, for capturing the high-frequency vibration state of the blade, and the optical axis angle between the first camera and the second camera is 10° to 30°; the processing device is used to acquire the images captured by the first camera and the second camera and determine the captured sample.

[0022] One embodiment of the present invention provides a non-transitory machine-readable medium for storing instructions, which, when executed by at least one processor, cause at least one processor to implement the above-described method for obtaining higher-order vibration modes of blades based on a medium- and low-speed camera.

[0023] The present invention relates to a method and system for obtaining higher-order vibration modes of blades based on a medium-to-low-speed camera. It uses a portion of the captured samples with a large displacement response at the location of maximum deformation as calculation samples. The displacement response data of the calculation samples contains a lower proportion of underlying noise. Obtaining higher-order vibration modes of the blade based on these calculation samples can improve the signal-to-noise ratio and reliability of the obtained higher-order vibration modes. Furthermore, selecting samples with even lower noise from the captured samples optimizes sample selection and improves computational efficiency.

[0024] The present invention relates to a method and system for obtaining high-order vibration modes of engine blades based on a medium- and low-speed camera. While ensuring the reliability of the obtained high-order vibration modes, it uses a low-frame-rate medium- and low-speed camera to obtain the high-order vibration modes of engine blades, which reduces the cost of instruments, breaks the dependence of high-frequency vibration measurement on high-speed or even ultra-high-speed cameras, and achieves a technological breakthrough. This is of great significance for ensuring the safe operation of engines. Attached Figure Description

[0025] The above-described features and advantages of the present invention will be better understood after reading the following detailed description of embodiments of the present disclosure in conjunction with the accompanying drawings. In the drawings, components are not necessarily drawn to scale, and components having similar related properties or features may have the same or similar reference numerals. Wherein:

[0026] Figure 1 This is a schematic diagram of the structure of a device for acquiring higher-order vibration modes of blades using a medium- and low-speed camera, as shown in some embodiments.

[0027] Figure 2 This is a structural block diagram of a system for acquiring higher-order vibration modes of blades based on a medium- and low-speed camera, as shown in some embodiments.

[0028] Figure 3 This is an exemplary flowchart of a method for obtaining higher-order vibration modes of blades based on a medium- and low-speed camera, according to some embodiments.

[0029] Figure 4 This is a schematic diagram of the images captured by the first and second cameras;

[0030] Figure 5 This is a schematic diagram of the location of maximum deformation on a certain photographed sample;

[0031] Figure 6 It is a displacement response trend diagram of several photographed samples;

[0032] Figure 7 It is a graph of the displacement response of several calculated samples;

[0033] Figure 8 This is a schematic diagram of higher-order vibration modes of the blade based on some embodiments; wherein,

[0034] (a) Top view of the blade's higher-order vibration modes; (b) Front view of the blade's higher-order vibration modes; (c) Side view of the blade's higher-order vibration modes; (d) Perspective view of the blade's higher-order vibration modes. Detailed Implementation

[0035] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. It should be noted that the aspects described below with reference to the accompanying drawings and specific embodiments are merely exemplary and should not be construed as limiting the scope of protection of the present invention in any way.

[0036] It should be understood that the terms “system,” “device,” “unit,” and / or “module” used herein are one method of distinguishing different components, elements, parts, sections, or assemblies at different levels. However, if other words can achieve the same purpose, they may be replaced by other expressions.

[0037] Flowcharts are used in this specification to illustrate the operations performed by the system according to embodiments of this specification. It should be understood that the preceding or following operations are not necessarily performed in exact order. Instead, the steps can be processed in reverse order or simultaneously. Furthermore, other operations can be added to these processes, or one or more steps can be removed from them.

[0038] It should be noted that the use of terms such as "first" and "second" to define features in this article is merely for the purpose of distinguishing the corresponding features. Unless otherwise stated, the above terms have no special meaning and therefore should not be construed as limiting the scope of protection of this invention.

[0039] Figure 1 This is a schematic diagram of a device for acquiring higher-order vibration modes of blades based on a medium- and low-speed camera, according to some embodiments.

[0040] like Figure 1 As shown, the blade high-order vibration mode acquisition device 100 based on a medium-low speed camera includes a processing device 110, a first camera 120, and a second camera 130.

[0041] Processing device 110 is used to execute method 300 for acquiring higher-order blade vibration modes based on a medium- and low-speed camera (see...) Figure 3 (and related descriptions). In some embodiments, the processing device 110 processes data and / or information from the first camera 120 and the second camera 130. For example, the processing device 110 acquires image data captured by the first camera 120 and the second camera 130 via a network or communication cable, and processes it. In some embodiments, the processing device acquires images captured by the first camera 120 and the second camera 130 and determines the captured samples. In some embodiments, the processing device 110 is local or remote. In some embodiments, the processing device 110 is implemented on a cloud platform.

[0042] Both the first camera 120 and the second camera 130 are low-to-medium speed cameras. Low-to-medium speed cameras have a low frame rate, typically less than 1000 FPS. The first camera 120 and the second camera 130 are configured for dual-target positioning to capture the high-frequency vibration state of the blade 140. In some embodiments, the angle between the optical axes of the first camera 120 and the second camera 130 is 10° to 30° (e.g., 15° to 20°) to facilitate accurate imaging of the blade 140.

[0043] In some embodiments, the vibration state of the blade 140 is provided by the vibration table 150 (or exciter). In some embodiments, the blade 140 is disposed on the vibration table 150, which provides a certain fixed-frequency excitation to the blade 140. After receiving the fixed-frequency excitation from the vibration table 150, the blade 140 vibrates. The vibration frequency of the blade 140 can be considered to be consistent with the excitation frequency provided by the vibration table 150, and the vibration frequency of the blade 140 is denoted as f. e In some embodiments, the excitation frequency of the vibration table 150 is consistent with the resonant frequency of the blade 140. In some embodiments, the vibration table 150 is communicatively connected to the processing device 110, and the processing device 110 presets the excitation frequency output or provided by the vibration table 150 according to the different test objects (i.e., blades).

[0044] In some embodiments, the device 100 for acquiring higher-order vibration modes of blades from a low-speed camera includes a non-transitory machine-readable medium (e.g., a memory) for storing data and / or instructions. In some embodiments, the machine-readable medium stores instructions or programs that can be invoked by the processing device 110, which, when executed by the processing device 110, enable the processing device 110 to implement the method 300 for acquiring higher-order vibration modes of blades from a low-speed camera. In some embodiments, the machine-readable medium stores processing data output by the processing device 110 and image acquisition data output by the first camera 120 and the second camera 130. In some embodiments, the machine-readable medium includes one or more storage components, each of which may be a separate device or part of another device. In some embodiments, the machine-readable medium is implemented on a cloud platform.

[0045] Figure 2 This is a structural block diagram of a system for acquiring higher-order vibration modes of blades based on a medium- and low-speed camera, as shown in some embodiments.

[0046] like Figure 2 As shown, the blade high-order vibration mode acquisition system 200 based on a medium-low speed camera includes a first determining module 210, a first obtaining module 220, a second determining module 230, and a second obtaining module 240.

[0047] The first determining module 210 is used to determine the location of the maximum deformation in the captured sample. The first determining module 210 determines the location of the maximum deformation in the captured sample based on the captured sample obtained by a medium-low speed camera. For more information on determining the location of the maximum deformation, please refer to [link to relevant documentation]. Figure 3 And its related descriptions.

[0048] The first acquisition module 220 is used to acquire the displacement response at the location of maximum deformation of the captured sample. For more information on acquiring the displacement response at the location of maximum deformation, please refer to [link to relevant documentation]. Figure 3 And its related descriptions.

[0049] The second determining module 230 is used to determine the calculation samples. The second determining module 230 determines the corresponding photographic samples as calculation samples by identifying the displacement response at the maximum deformation position within a relatively large range. In some embodiments, the second determining module 230 is further used to determine the maximum displacement response value, where the maximum displacement response value refers to the maximum value of the displacement response corresponding to the maximum deformation position among several photographic samples. The second determining module 230 determines the corresponding photographic samples whose displacement response is within 70% to 100% of the maximum displacement response value as calculation samples. For more information on determining the calculation samples, see [link to relevant documentation]. Figure 3 And its related descriptions.

[0050] The second acquisition module 240 is used to obtain the full-field displacement response corresponding to the calculated sample, in order to determine the higher-order vibration modes of the blade. For more information on obtaining the full-field displacement response corresponding to the calculated sample, please refer to [link to relevant documentation]. Figure 3 And its related descriptions.

[0051] In some embodiments, the blade higher-order vibration mode acquisition system 200 based on a low-to-medium speed camera further includes a preset module for presetting the shooting frame rate and exposure time of the camera (e.g., the first camera 120 and the second camera 130). For more information on preset camera shooting frame rate and exposure time, see [link to documentation]. Figure 3 And its related descriptions.

[0052] Figure 3 This is an exemplary flowchart illustrating a method for obtaining higher-order vibration modes of blades based on a low-to-medium speed camera, according to some embodiments. In some embodiments, method 300 is executed by a processing device. Figure 3 As shown, method 300 includes the following steps:

[0053] Step 310: Based on the images obtained by the medium-low speed camera, determine the location of the maximum deformation in the images.

[0054] In some embodiments, before obtaining the photographed sample, the shooting frame rate and exposure time of the camera (e.g., the first camera 120 and the second camera 130) are preset. In some embodiments, since the shooting frame rate of the low-speed camera itself is low, the shooting frame rate of the camera is preset to the maximum frame rate that it can achieve in order to facilitate the shooting of the high-frequency vibration state of the blade. The exposure time affects the quality of the acquired photographed sample. On the one hand, if the exposure time is too short, the camera may not have enough light, affecting the image quality. On the other hand, if the exposure time is too long, the blade will vibrate and deform a lot during the exposure period, causing motion blur and failing to capture transient deformation features. Therefore, an appropriate exposure time should be preset. In some embodiments, the exposure time Δt is determined by the following formula:

[0055]

[0056] Among them, f e The vibration frequency of the blade in response to a fixed-frequency excitation. In some embodiments, the exposure time Δt is determined by the following formula:

[0057]

[0058] In some embodiments, the exposure time Δt is determined by the following formula:

[0059]

[0060] In some embodiments, when the vibration table excites the blade to maintain high-frequency vibration, a camera is triggered to capture a sufficient number of blade vibration images as shooting samples at a preset exposure time and shooting frame rate. As an example only, the camera is repeatedly triggered to capture multiple images at the preset exposure time and shooting frame rate to obtain a sufficient number of blade vibration images as shooting samples, with the time interval between the multiple captures being a random number. In some embodiments, the number of shooting samples obtained by the low-to-medium speed camera is several, and the location of the maximum deformation in the shooting sample is determined based on any one of the several shooting samples. In some embodiments, the number of shooting samples obtained by the camera within a time period is several, and the location of the maximum deformation in the shooting sample is determined based on any one of the several shooting samples. In some embodiments, the camera includes a first camera and a second camera, such as... Figure 4 As shown, the first and second cameras acquire several images within a time period. Each camera captures a blade vibration image at a specific time point. A single image at that time point includes a pair of blade vibration images captured by the first and second cameras. In some embodiments, based on a reference sample, the transient displacement response of any single image is extracted. The location of maximum deformation of the image is determined according to the magnitude of the transient displacement response at various points on the blade. Figure 5 The maximum deformation location is shown as 51. The reference sample is a still image of the blade taken by a camera when the blade is stationary. For example, using DIC analysis software, the transient displacement response of the captured sample is extracted by comparing the reference sample and the captured sample. Based on the magnitude of the transient displacement response at each point on the blade, the maximum deformation location of the captured sample is determined.

[0061] Step 320: Obtain the displacement response at the location of maximum deformation of the photographed sample.

[0062] In some embodiments, since the blade structure remains unchanged and the mode shape is the same at the same vibration frequency, the maximum deformation position on several photographed samples obtained within a time period is considered to be consistent. After the maximum deformation position is determined based on step 310, the displacement response of the maximum deformation position of several photographed samples is obtained based on the position information (e.g., coordinate information) of the maximum deformation position. The first response sequence of the maximum deformation position of N photographed samples is denoted as [R1, R2, ... RN], where R refers to the displacement response of the maximum deformation position.

[0063] Step 330: Determine the calculation sample, which is the corresponding photographic sample with displacement response over a large range.

[0064] In some embodiments, the larger range includes 70% to 100% of the maximum displacement response value, where the maximum displacement response value refers to the maximum value of the displacement response corresponding to the maximum deformation position among several captured samples. The maximum value of the displacement response corresponding to the maximum deformation position is denoted as Rmax, where Rmax is the maximum value in the displacement response sequence. The first response sequence [R1, R2, ... RN] is filtered to select a second response sequence whose displacement response falls within the range of 70% to 100% of Rmax. The captured samples corresponding to the second response sequence are then used as the calculated samples. In some embodiments, the larger range includes 80% to 100% of the maximum displacement response value. In some embodiments, to further improve the signal-to-noise ratio, the larger range includes 90% to 100% of the maximum displacement response value.

[0065] like Figure 6 As shown, the horizontal axis represents the sample number, and the vertical axis represents the displacement response at the location of maximum deformation in the sample. The maximum displacement response value Rmax is determined, and samples whose displacement response at the location of maximum deformation falls within the range of 90% to 100% Rmax are selected as calculation samples. The displacement response curves of the selected calculation samples are shown below. Figure 7 As shown, the horizontal axis represents the sample number, and the vertical axis represents the displacement response at the location of the maximum deformation in the sample.

[0066] Since the underlying noise of blade vibration is fixed, the deformation at the maximum deformation location is large, resulting in a large displacement response and a low proportion of underlying noise in the displacement response data. In some embodiments of this specification, the displacement response at the maximum deformation location is used as the object, and images with displacement responses within 70% to 100% of the maximum displacement response value are selected as calculation samples. The displacement response data of the calculated samples contain an even lower proportion of underlying noise. Obtaining higher-order vibration modes of the blade based on these calculated samples can improve the signal-to-noise ratio of the obtained higher-order vibration modes. Figure 7 The displacement response curve shown in the figure is compared to Figure 6 The displacement response shown tends to be more pronounced. Figure 7 The displacement response data shown contains a lower proportion of low-level noise, resulting in a higher signal-to-noise ratio for the higher-order vibration modes calculated from the sample data, thus improving the reliability of the obtained higher-order vibration modes. Furthermore, selecting samples with lower noise from the captured data for calculation optimizes sample selection and improves computational efficiency.

[0067] Step 340: Obtain the full-field displacement response corresponding to the calculated sample in order to determine the higher-order vibration modes of the blade.

[0068] In some embodiments, a reference sample is used as a comparison to determine the blade's full-field displacement response corresponding to the calculated sample. For example, using DIC analysis software, the reference sample and the calculated sample are compared one by one, and the transient displacement response at each location point of the calculated sample is extracted to determine the full-field displacement response corresponding to the calculated sample. In some embodiments, the higher-order vibration modes of the blade can be obtained by averaging the full-field displacement responses corresponding to multiple calculated samples.

[0069] The higher-order vibration modes obtained based on method 300 are as follows: Figure 8 As shown. Figure 8 (a) shows a top view of a higher-order mode shape; Figure 8 (b) shows a front view of a higher-order mode shape; Figure 8 (c) shows a side view of a higher-order mode shape; Figure 8 Figure (d) shows a three-dimensional view of the higher-order vibration modes. The higher-order vibration modes obtained based on method 300 are close to the actual vibration modes and have little difference from the vibration modes obtained by simulation calculation. However, the blade vibration modes obtained by existing methods using medium- and low-speed cameras have higher uncertainty and have a larger difference from the vibration modes obtained by simulation calculation.

[0070] The basic concepts have been described above. It is clear that the detailed disclosure above is merely illustrative and does not constitute a limitation of this specification, especially for those skilled in the art. Furthermore, unless expressly stated in the claims, the order of elements and sequences, the use of numbers and letters, or other names in this specification are not intended to limit the order of the processes and methods described herein. Although various examples of currently considered useful embodiments of the invention have been discussed in the foregoing disclosure, it should be understood that such details are for illustrative purposes only, and the appended claims are not limited to the disclosed embodiments. Rather, the claims are intended to cover all modifications and equivalent combinations that conform to the substance and scope of the embodiments described herein.

Claims

1. A method for obtaining higher-order vibration modes of blades based on a medium- and low-speed camera, characterized in that, include: Based on the images obtained by the medium- and low-speed camera, determine the location of the maximum deformation in the images; Obtain the displacement response at the location of maximum deformation of the captured sample; Determine the calculation sample, which is the corresponding image sample of the displacement response within a large range; The full-field displacement response corresponding to the calculated sample is obtained to determine the higher-order vibration modes of the blade.

2. The method for obtaining higher-order vibration modes of blades based on a medium- and low-speed camera according to claim 1, characterized in that, The larger range includes 70% to 100% of the maximum displacement response value, wherein the maximum displacement response value refers to the maximum value of the displacement response corresponding to the maximum deformation position among a plurality of the captured samples.

3. The method for obtaining higher-order vibration modes of blades based on a medium- and low-speed camera according to claim 1, characterized in that, The number of images captured by the medium-low speed camera is several. Based on any one of the several images captured, the position of the maximum deformation in the images captured is determined.

4. The method for obtaining higher-order vibration modes of blades based on a medium- and low-speed camera according to claim 1, characterized in that, The higher-order vibration modes of the blade are determined by averaging the full-field displacement response of the calculated sample.

5. The method for obtaining higher-order vibration modes of blades based on a medium- and low-speed camera according to claim 1, characterized in that, Before obtaining the captured sample, the camera's exposure time is preset; The exposure time Δt is determined by the following formula: Among them, f e The vibration frequency of the blade in response to the fixed-frequency excitation.

6. A system for acquiring higher-order vibration modes of blades based on a medium- and low-speed camera, characterized in that, The system includes a first determining module, a first obtaining module, a second determining module, and a second obtaining module; wherein, The first determining module is used to determine the location of the maximum deformation in the captured sample based on the captured sample obtained by the medium-low speed camera; The first obtaining module is used to obtain the displacement response at the position of maximum deformation of the photographed sample; The second determining module is used to determine the calculation sample, which is the corresponding photographed sample of the displacement response within a large range; The second obtaining module is used to obtain the full-field displacement response corresponding to the calculated sample in order to determine the higher-order vibration modes of the blade.

7. The system for acquiring higher-order vibration modes of blades based on a medium- and low-speed camera according to claim 6, characterized in that, The second determining module is used to determine the maximum displacement response value, wherein the maximum displacement response value refers to the maximum value of the displacement response corresponding to the maximum deformation position among a plurality of the captured samples; The second determining module determines the captured sample corresponding to the displacement response within the range of 70% to 100% of the maximum displacement response value as the calculated sample.

8. The system for acquiring higher-order vibration modes of blades based on a medium- and low-speed camera according to claim 6, characterized in that, The system also includes a preset module, which is used to preset the shooting frame rate and exposure time of the camera; The preset module determines the maximum frame rate of the camera as the shooting frame rate; The preset module determines the exposure time Δt using the following formula: Among them, f e The vibration frequency of the blade in response to the fixed-frequency excitation.

9. A device for acquiring higher-order vibration modes of blades based on a medium- and low-speed camera, characterized in that, The apparatus includes a processing device for performing the method for obtaining higher-order vibration modes of blades based on a medium-low speed camera as described in any one of claims 1-5.

10. The device for acquiring higher-order vibration modes of blades based on a medium- and low-speed camera according to claim 9, characterized in that, The device includes a first camera and a second camera, which are configured for dual-target positioning to capture the high-frequency vibration state of the blade. The optical axis angle between the first camera and the second camera is 10° to 30°. The processing device is used to acquire images captured by the first camera and the second camera, and to determine the captured sample.

11. A non-transitory, machine-readable medium for storing instructions, characterized in that, When executed by at least one processor, the instructions cause the at least one processor to implement the method for obtaining higher-order vibration modes of blades based on a medium-low speed camera as described in any one of claims 1 to 5.

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