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Method of recognizing asynchronous vibration parameters of blades under variable speed excitation

A technology of vibration parameters and identification methods, which is applied in the direction of measuring vibration, vibration measurement in solids, and measuring devices, and can solve problems such as difficulty

Inactive Publication Date: 2015-06-10
NANJING UNIV OF AERONAUTICS & ASTRONAUTICS
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Problems solved by technology

The blade tip timing method of non-contact measurement only measures one vibration signal of the blade in a week, and the sampling frequency is the rotational speed. Generally, the vibration frequency of the blade is above kHz, and the sampling frequency is only a few hundred Hz. Therefore, parameter identification is a serious undersampling signal. Under the identification, there is a certain degree of difficulty and particularity

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  • Method of recognizing asynchronous vibration parameters of blades under variable speed excitation
  • Method of recognizing asynchronous vibration parameters of blades under variable speed excitation
  • Method of recognizing asynchronous vibration parameters of blades under variable speed excitation

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[0024] The method for identifying asynchronous vibration parameters of blades under variable speed excitation proposed by the present invention will be described in detail below in conjunction with the accompanying drawings.

[0025] The single-blade single-degree-of-freedom vibration displacement equation can be expressed as:

[0026]

[0027] Among them: A is the vibration amplitude, is the initial phase, i=0,1,2,...,M-1, M is the number of sensors, t i Sampling interval.

[0028] Because the vibration frequency of the blade is a non-integer multiple of the rotational speed, ω=(m+Δm)Ω, (m+Δm) is the asynchronous vibration order, where m is a positive integer, Δm is a decimal between 0 and 1, and Ω is speed frequency, and let t i =(θ i +2πn) / Ω, θ i is the installation angle of the sensor, and n is the number of rotations. Therefore, formula (1) can be transformed into:

[0029]

[0030] in And Δm=Δω / Ω, Δω is the aliasing frequency, substituting into formula (2...

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Abstract

The invention discloses a method of recognizing asynchronous vibration parameters of blades under variable speed excitation. According to the method, aliasing frequency is acquired by means of increasing sampling rate by interpolation of measurement data of adjacent two blades, vibration aliasing frequency and phase is acquired by full-phase FFT (fast Fourier transform), and a fractional part of non-integer order is acquired; order tracking is performed according to a relation between the phase and the sensor mounting angle, and an integral part of asynchronous vibration order of the blades is recognized; an algorithm is verified by deceleration multi-octave asynchronous vibration data generated by a four-blade simulation model, simulation data is vibration data of the single blade measured by a single sensor, recognition results are compared to simulation parameters, and the ability of the algorithm to correctly recognize the asynchronous vibration parameters of the blades is verified. The method is correct, reliable, simple and feasible.

Description

technical field [0001] The invention belongs to the technical field of turbomachinery blade testing, in particular to a blade asynchronous vibration parameter identification method. Background technique [0002] The blade is an important part of the turbomachinery, and its reliable operation is the key to ensure the safe operation of the rotating machinery. The current method of measuring the vibration of the blade adopts the non-contact measurement of the blade tip timing method. The blade tip timing vibration measurement technology is to use the blade tip timing sensor along the It is radially installed on the relatively static shell of the rotating machine. According to the difference between the pulse time t of the blade arriving at the sensor and the theoretical arrival time, the subsampling sequence of blade vibration is obtained, and the blade vibration parameters are obtained by using a special parameter identification method. The blade tip timing method of non-conta...

Claims

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Application Information

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IPC IPC(8): G01H1/14
Inventor 岳林李海洪王德友王磊胡伟
Owner NANJING UNIV OF AERONAUTICS & ASTRONAUTICS
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