CN-122016027-A - Method and system for acquiring high-order vibration mode of blade based on medium-low speed camera

CN122016027ACN 122016027 ACN122016027 ACN 122016027ACN-122016027-A

Abstract

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

Inventors

CHEN WEI
JIN MENGSHI
GU XIAOHUA
PAN WEI
ZHANG GUANGZE

Assignees

中国航发商用航空发动机有限责任公司

Dates

Publication Date: 20260512
Application Date: 20241111

Claims (11)

1. The method for acquiring the blade high-order vibration mode based on the medium-low speed camera is characterized by comprising the following steps of: Determining a maximum deformation position in a shooting sample based on the shooting sample obtained by a medium-low speed camera; obtaining a displacement response of the maximum deformation location of the captured sample; determining a calculation sample, wherein the calculation sample is a corresponding shooting sample of the displacement response in a larger range; And obtaining full-field displacement response corresponding to the calculated sample so as to determine the high-order vibration mode of the blade.
2. The method for obtaining the high-order vibration mode of the blade based on the medium-low speed camera according to claim 1, wherein the larger range comprises a range of 70% -100% of a maximum displacement response value, and the maximum displacement response value is a maximum value of displacement responses corresponding to the maximum deformation positions in the plurality of shot samples.
3. The method for acquiring a blade higher order vibration mode based on a low-medium speed camera according to claim 1, wherein the number of the shot samples obtained by the low-medium speed camera is a plurality, and the maximum deformation position in the shot samples is determined based on any one of the plurality of shot samples.
4. The method for acquiring a high-order vibration mode of a blade based on a medium-low speed camera according to claim 1, wherein the high-order vibration mode of the blade is determined by averaging the full-field displacement response of the calculation sample.
5. The method for acquiring a blade higher order vibration mode based on a medium-low speed camera according to claim 1, wherein an exposure time of the camera is preset before the photographed sample is acquired; the exposure time Δt is determined by: wherein f e is the vibration frequency of the blade in response to the fixed frequency excitation.
6. The system is characterized by comprising a first determining module, a first obtaining module, a second determining module and a second obtaining module, wherein, The first determining module is used for determining the maximum deformation position in a shooting sample based on the shooting sample obtained by the medium-low speed camera; the first obtaining module is used for obtaining a displacement response of the maximum deformation position of the shooting sample; the second determining module is used for determining a calculation sample, wherein the calculation sample is a corresponding shooting sample of which the displacement response is in a larger range; the second obtaining module is used for obtaining full-field displacement response corresponding to the calculated sample so as to determine the high-order vibration mode of the blade.
7. The system for obtaining a higher-order vibration mode of a blade based on a low-medium speed camera according to claim 6, wherein the second determining module is configured to determine a maximum displacement response value, where the maximum displacement response value is a maximum value of the displacement responses corresponding to the maximum deformation positions in the plurality of photographed samples; And the second determining module determines the corresponding shooting sample with the displacement response within the range of 70% -100% of the maximum displacement response value as the calculation sample.
8. The system for acquiring the blade higher-order vibration modes based on the medium-low speed camera according to claim 6, wherein the system further comprises a preset module for presetting a shooting frame rate and an 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 by: wherein f e is the vibration frequency of the blade in response to the fixed frequency excitation.
9. A device for acquiring a blade high-order vibration mode based on a medium-low speed camera, characterized in that the device comprises a processing device for executing the method for acquiring a blade high-order vibration mode based on a medium-low speed camera according to any one of claims 1 to 5.
10. The device for acquiring the high-order vibration mode of the blade based on the medium-low speed camera according to claim 9, wherein the device comprises a first camera and a second camera, the first camera and the second camera are designed as binocular targets and are used for shooting the high-frequency vibration state of the blade, and the included angle of the optical axes of the first camera and the second camera is 10-30 degrees; The processing device is used for acquiring photographed images of the first camera and the second camera and determining the photographed sample.
11. A non-transitory, obtained machine-readable medium storing instructions which, when executed by at least one processor, cause the at least one processor to implement the method of obtaining a blade high order mode of vibration based on a low and medium speed camera of any one of claims 1 to 5.

Description

Method and system for acquiring high-order vibration mode of blade based on medium-low speed camera Technical Field The invention relates to the technical field of vibration measurement, in particular to a method and a system for acquiring a blade high-order vibration mode based on a medium-low speed camera. Background The running state of the high-pressure compressor or the turbine of the engine can excite a high-order mode of blade vibration, and the possibility of blade crack occurrence is greatly improved due to high-cycle fatigue caused by the high-order and high-frequency high-order mode, so that the running safety of the engine is endangered. Therefore, the method for obtaining the high-order modal characteristics of the blade has important effects of optimizing the blade configuration and prolonging the service life of the blade. The high-order natural frequency of the blade often exceeds 1500Hz, the vibration mode corresponding to the high-order mode (hereinafter referred to as high-order vibration mode for short) is very complex, the node line distribution is very rich, only the natural frequency of a test piece is obtained through single-measuring point measurement, so that the mode result obtained through finite element calculation of the blade cannot correspond to the test result, and in addition, denser mode distribution exists in the high-frequency state, the real blade vibration mode needs to be obtained, so that the mode judgment and the finite element obtaining result correction are needed. In order to obtain the high-order vibration mode of the blade, the existing technical means comprise the following steps that an acceleration sensor is adopted, but the acceleration sensor has larger additional mass and can influence the vibration mode of the blade, a strain gauge is adopted to obtain the high-order vibration mode of the blade, the required quantity is larger, the manpower and resource cost is higher, and a Doppler scanning laser vibration meter can accurately obtain the high-order vibration mode of the blade, but the required scanning time is longer, and the blade has the risk of damage under high-frequency excitation. Currently, in comprehensive terms, an imaging measurement scheme using a high-speed camera is one of schemes for obtaining the high-order vibration mode of a blade. The high-speed camera has high sampling frequency, and can better realize the acquisition of the high-order vibration mode of the blade, however, the high-speed camera, including the ultra-high-speed camera, cannot be directly acquired through commercial channels due to technical limitations. But the medium-low speed cameras are gradually domesticated at present, and the acquisition channel is easier. Therefore, the high-order vibration mode of the engine blade is obtained based on the medium-speed camera, and the method has important significance for ensuring the safe operation of the engine. Therefore, an attempt is made to provide a method and a system for obtaining a blade high-order vibration mode based on a medium-low speed camera. Disclosure of Invention The invention at least aims to provide a method for acquiring a high-order vibration mode of a blade based on a medium-low speed camera, which adopts the medium-low speed camera to realize the measurement of the high-order vibration mode of the engine blade in a high-frequency vibration state. The following presents a simplified summary of one or more aspects in order to provide a basic understanding of such aspects. This summary is not an extensive overview of all contemplated aspects, and is intended to neither identify key or critical elements of all aspects nor delineate the scope of any or all aspects. Its sole purpose is to present some concepts of one or more aspects in a simplified form as a prelude to the more detailed description that is presented later. One of the embodiments of the invention provides a method for acquiring a blade high-order vibration mode based on a medium-low speed camera, which comprises the steps of determining the maximum deformation position in a shooting sample based on a large number of shooting samples obtained by the medium-low speed camera; the method comprises the steps of obtaining displacement response of the maximum deformation position of a shooting sample, determining a calculating sample, wherein the calculating sample is a corresponding shooting sample with the displacement response in a larger range, and obtaining full-field displacement response corresponding to the calculating sample so as to determine the high-order vibration mode of the blade. In some embodiments, the larger range includes a range of 70% -100% of a maximum displacement response value, where the maximum displacement response value is a maximum value of displacement response corresponding to a maximum deformation position in the plurality of photographed samples. In some embodiments, the number of shot samples obtained by the medium-lo