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CN-117034536-B - Rotor blade damping ratio calculation method

CN117034536BCN 117034536 BCN117034536 BCN 117034536BCN-117034536-B

Abstract

The present disclosure discloses a method for calculating a damping ratio of a rotor blade, comprising collecting time pulse signals of a blade tip by using two blade tip timing sensors, collecting a rotational speed reference pulse signal of the blade by using one OPR sensor, obtaining a rotational period T OPR of the rotor blade according to the rotational speed signal, and obtaining an actual arrival time based on the blade And calculating displacement data of the tip of the rotor blade with a rotation period T OPR Tip-based displacement data Extracting displacement trend curves of two sensors, calculating standard deviation of first derivatives of the two displacement trend curves, searching for the resonance center time t m of the blade, calculating the resonance frequency F of the blade by combining the known first-order modal frequency F n of the rotor blade, performing time-frequency analysis on a time pulse signal of the rotor blade to obtain a frequency response curve of the rotor blade, and fitting the frequency response curve by nonlinear least square based on the resonance frequency F to obtain the damping ratio ζ of the rotor blade.

Inventors

  • YANG ZHIBO
  • LI HAOQI
  • HU HUAHUI
  • CHEN XUEFENG
  • TIAN SHAOHUA
  • ZHANG XINGWU
  • CAO JIAHUI

Assignees

  • 西安交通大学

Dates

Publication Date
20260512
Application Date
20230619
Priority Date
20230515

Claims (10)

  1. 1. A method of rotor blade damping ratio calculation, comprising the steps of: step 1, collecting time pulse signals of the rotor blade by using two blade end timing sensors, and obtaining the actual arrival time of the rotor blade according to the time pulse signals Collecting a rotating speed reference pulse signal of the rotor blade by using an OPR sensor, and obtaining a rotating period T OPR of the rotor blade according to the rotating speed reference pulse signal; step2 based on the actual arrival time of the rotor blade And the rotation period T OPR calculates the actual angle of arrival of the rotor blade Step 3, according to the radius R of the rotor blade and the actual arrival angle of the rotor blade Angle of arrival from theory Angle difference of (2) Calculating displacement data of blade tips Step 4, based on the displacement data of the blade tip Extracting displacement trend curves of two leaf-end timing sensors, calculating standard deviation of first derivatives of the two displacement trend curves, and taking time corresponding to the maximum standard deviation as resonance center time t m of the rotor blade; Step 5, searching a resonance frequency F r corresponding to the resonance center time t m of the rotor blade based on a time-frequency curve of the rotating speed reference pulse signal, and calculating the resonance frequency F of the rotor blade by combining the known first-order modal frequency F n of the rotor blade; step 6, performing time-frequency analysis on the time pulse signals of the rotor blade to obtain a time-frequency diagram; And 7, extracting formant ridgelines in the time-frequency diagram to obtain a frequency response curve of the rotor blade, and fitting the frequency response curve based on the resonance frequency F of the rotor blade in the step 5 by nonlinear least square to obtain the damping ratio zeta of the rotor blade.
  2. 2. The method according to claim 1, wherein, preferably, in step 1, the mounting angles of the two dual sensors satisfy the following formula: Wherein k is such that it satisfies EO p is the resonance order of interest in the test.
  3. 3. The method according to claim 1, wherein in step 2, the actual angle of arrival of the rotor blade Calculated by the following formula: Wherein, the Representing the actual arrival time of the rotor blade, T OPR represents the rotation period of the rotor blade.
  4. 4. The method of claim 1, wherein in step 3, the theoretical angle of arrival of the rotor blade Calculated by the following formula: wherein the subscript i denotes the number of the rotor blade, the subscript j denotes the number of the sensor, n denotes the number of rotations of the rotor blade, and M denotes that the rotor blade has rotated M rotations.
  5. 5. The method of claim 1, wherein in step 3, the displacement data of the rotor blade Calculated by the following formula: wherein R represents the radius of the rotor blade, pi represents the circumference ratio, Representing the actual angle of arrival of a rotor blade Angle of arrival from theory Is provided with a plurality of angular differences,
  6. 6. The method of claim 1, wherein in step 4, the standard deviation of the first derivative of the displacement trend curve is calculated by: Wherein, the Representing the first derivative of the signal measured by the jth sensor for the ith blade at the nth turn, Representing the standard deviation of the derivative of the two sensor signals of blade number i at turn n, Representing the mean of the first derivatives of the two sensor trend signals.
  7. 7. The method of claim 1, wherein in step 5, the resonant frequency F i of the rotor blade is calculated by: F i ＝f ri EO Where f n denotes the first order modal frequency of the rotor blade, f ri denotes the corresponding rotation frequency of the rotor blade at time t i , EO denotes the order of the resonance frequency of the rotor blade, [. Cndot. ] denotes the rounded-off rounding value.
  8. 8. The method of claim 1, wherein in step 7, the damping ratio ζ of the rotor blade is calculated by: Where m represents the mass of the rotor blade, c represents the damping of the rotor blade, k represents the stiffness of the rotor blade, ω n represents the natural frequency of the rotor blade.
  9. 9. An electronic device, comprising: a memory, a processor, and a computer program stored on the memory and executable on the processor, wherein, The processor, when executing the program, implements the method of any one of claims 1 to 8.
  10. 10. A computer storage medium, characterized in that, the computer storage medium stores computer-executable instructions, the computer executable instructions are for performing the method of any one of claims 1 to 8.

Description

Rotor blade damping ratio calculation method Technical Field The disclosure belongs to the field of rotor blade online monitoring and dynamic parameter identification, and particularly relates to a rotor blade damping ratio calculation method. Background Turbomachinery is widely used in industry, particularly in the fields of aviation, navigation and electrical energy. The blade is an important part for ensuring performance and operation safety of the turbine machinery, but because the blade is impacted by high temperature and high pressure, alternating load and foreign objects for a long time, the service life of the blade is influenced, and the operation safety of the whole machine is threatened, so that the vibration state detection of the blade is very important. The traditional contact type measuring method, such as strain gauge measurement, has high system complexity and low efficiency, is difficult to apply to the actual industrial environment, and Blade tip timing (Blade TIP TIMING, BTT) is a non-contact type method, which records the arrival time pulse of the Blade by using a probe (capacitive type, optical fiber type, electric vortex type and the like) installed in a casing, converts the theoretical arrival angle and the actual arrival angle difference under the condition of not considering the vibration of the Blade into Blade tip displacement, thereby obtaining the vibration displacement of the Blade tip, and analyzes the health condition of the Blade according to the vibration displacement. The traditional rotor blade damping ratio estimation can only be measured through a strain gauge, but the undersampling characteristic of the blade tip timing signal causes that the method is difficult to collect the maximum displacement of blade resonance, so that a larger error occurs in the amplitude response curve fitting result. Disclosure of Invention In view of the shortcomings in the prior art, an object of the present disclosure is to provide a rotor blade damping ratio calculation method, which can obtain a natural frequency and a damping ratio from strictly undersampled tip timing data, so as to realize health monitoring of a blade. In order to achieve the above object, the present disclosure provides the following technical solutions: a method of rotor blade damping ratio calculation, comprising the steps of: step 1, collecting time pulse signals of the rotor blade by using two blade end timing sensors, and obtaining the actual arrival time of the rotor blade according to the time pulse signals Collecting a rotating speed reference pulse signal of the rotor blade by using an OPR sensor, and obtaining a rotating period T OPR of the rotor blade according to the rotating speed reference pulse signal; step2 based on the actual arrival time of the rotor blade And the rotation period T OPR calculates the actual angle of arrival of the rotor blade Step 3, according to the radius R of the rotor blade and the actual arrival angle of the rotor bladeAngle of arrival from theoryAngle difference of (2)Calculating displacement data of blade tips Step 4, based on the displacement data of the blade tipExtracting displacement trend curves of two leaf-end timing sensors, calculating standard deviation of first derivatives of the two displacement trend curves, and taking time corresponding to the maximum standard deviation as resonance center time t m of the rotor blade; Step 5, searching a resonance frequency F r corresponding to the resonance center time t m of the rotor blade based on a time-frequency curve of the rotating speed reference pulse signal, and calculating the resonance frequency F of the rotor blade by combining the known first-order modal frequency F n of the rotor blade; step 6, performing time-frequency analysis on the time pulse signals of the rotor blade to obtain a time-frequency diagram; And 7, extracting formant ridgelines in the time-frequency diagram to obtain a frequency response curve of the rotor blade, and fitting the frequency response curve based on the resonance frequency F of the rotor blade in the step 5 by nonlinear least square to obtain the damping ratio zeta of the rotor blade. Preferably, in step 1, the installation angle of the two dual sensors satisfies the following formula: wherein k is such that Satisfy the following requirementsEO p is the resonance order of interest in the test. Preferably, in step2, the actual angle of arrival of the rotor bladeCalculated by the following formula: Wherein, the Representing the actual arrival time of the rotor blade, T OPR represents the rotation period of the rotor blade. Preferably, in step 3, the theoretical angle of arrival of the rotor bladeCalculated by the following formula: wherein the subscript i denotes the number of the rotor blade, the subscript j denotes the number of the sensor, n denotes the number of rotations of the rotor blade, and M denotes that the rotor blade has rotated M rotations. Preferably, in step 3, the dis