High-frequency blade passing frequency extraction method based on vibration signals of outer casing of gas turbine

Abstract

The invention discloses a gas turbine high-frequency blade passing frequency extraction method based on a vibration signal of a gas turbine outer casing, and relates to the technical field of signal conversion and feature extraction under a variable-speed working condition of a gas turbine, and the method can more accurately and effectively extract and separate the passing frequency component of each stage of high-frequency blade of the gas turbine under a key-phase-free condition. Single-component signal vibration waveform reconstruction is realized, and the method can be used for accurate extraction of vibration characteristics. The method comprises the following steps: acquiring a vibration acceleration signal of a to-be-evaluated gas turbine outer casing by using a vibration acceleration sensor; time-frequency distribution of vibration signals is obtained through short-time Fourier transform, a time-frequency curve with good time-frequency aggregation is obtained through local maximum synchronous extrusion transform (LMSST), a frequency multiplication rotation frequency curve of a rotor is extracted from the time-frequency curve, the frequency multiplication curve of the rotor is multiplied by the number of blades of each stage, and theoretical calculation values of passing frequencies of the blades of each stage can be obtained. And reducing the search range of the time-frequency distribution through the theoretical calculation value of the frequency by depending on each level of blade.

Description

technical field [0001] The invention relates to the technical field of signal conversion and feature extraction under the variable speed working condition of a gas turbine, in particular to a high-frequency blade passing frequency extraction method based on the vibration signal of the outer casing of the gas turbine. Background technique [0002] Gas turbines have been widely used in my country's aerospace, shipbuilding and petrochemical industries. The working environment of gas turbines is harsh, and the operating environment is under high temperature, high pressure, and high speed conditions for a long time, which is prone to failure. Blades are one of the key components of rotating machinery such as gas turbines. According to foreign media reports, the failure of gas turbine blades accounts for 42% of the total failures of gas turbines. Faults such as breakage of blades and detachment of attachments on blades will directly affect the operating status of the equipment. ...

AI Technical Summary

Problems solved by technology

Early time-frequency analysis methods such as wavelet transform and short-time Fourier transform are mainly suitable for analyzing linear and stable vibration signals. Due to the influence of Heisenberg uncertainty, when faced with the variable speed of gas turbines, the gas turbine The high-frequency blade vibration signal changes rapidly, and the time-frequency extraction results have the disadvantages of low time-frequency resolution and energy divergence, which cannot accurately separate and extract individual components in the gas turbine vibration signal

Therefore, there are still some deficiencies in the research on the frequency extraction of high-frequency blades of gas turbines, and the improvement of time-frequency aggregation and the accuracy of frequency extraction of high-frequency blades need to be resolved.

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