Pump cavitation inception identification method based on balanced square envelope spectrum

An identification method and envelope spectrum technology are applied in the field of pump cavitation incipient identification based on balanced square envelope spectrum, which can solve the problems of insensitivity to local faults, low resolution, and poor variance performance, and improve signal anti-noise capability. , The effect of simple operation and strong anti-noise ability

Active Publication Date: 2019-08-27
ZHEJIANG UNIV
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  • Claims
  • Application Information

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Problems solved by technology

However, it has limitations such as complex calculation, poor variance performance, low resolution, and insensitivity to local faults, and it is only good for stationary signal processing.

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  • Pump cavitation inception identification method based on balanced square envelope spectrum
  • Pump cavitation inception identification method based on balanced square envelope spectrum
  • Pump cavitation inception identification method based on balanced square envelope spectrum

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Embodiment Construction

[0043] The balanced squared envelope spectrum mainly uses two statistics, namely kurtosis and autocovariance. Kurtosis is a statistical metric that measures the peak value of a data set and thus can be used to detect fault shocks in signals related to rotating machinery. defined as where Y(t i , f) is obtained by moving a constant length window (Nw) along the signal at time t i The obtained signal x(t i ) short-time Fourier transform. is the operator for averaging. Autocovariance is the calculation of the squared envelope of the signal, defined as Among them, X is the square envelope of the filtered signal, τ=q / f s is the delay factor. Calculating the autocovariance has the benefit of eliminating uncorrelated components of the signal, namely noise and random impulse content, neither of which are related to any particular fault. In addition, the periodic part of the signal is enhanced, so that the signal-to-noise ratio of each demodulated frequency band signal increa...

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Abstract

The invention discloses a pump cavitation inception identification method based on a balanced square envelope spectrum. The method comprises the following steps that (1) vibration signals of a pump are collected, and the decomposition order is determined; (2) the vibration signals are filtered by utilizing the maximum overlapped discrete wavelet packet transformation to be converted into signals after all filtering frequency bands; (3) the square envelope of the signals in each filtering frequency band is calculated; (4) kurtosis values of the square envelopes are calculated, the filtering frequency band with the highest kurtosis value is selected in each decomposition layer, and half of the kurtosis value is taken as a threshold value; (5) the frequency band which is larger than the threshold value is selected in each decomposition layer, the square envelope spectrum of the signals is calculated in each frequency band, and accumulating is carried out after normalization; and (6) all the square envelope spectrums obtained by all the decomposition layers are accumulated to obtain a balance square envelope spectrum, and the frequency characteristics of the fault signals are analyzed.By means of the method, the fault signal of cavitation inception can be detected, and the normal working condition and the cavitation inception working condition of the pump can be distinguished.

Description

technical field [0001] The invention belongs to the field of signal processing, in particular to a pump cavitation primary identification method based on an equalized square envelope spectrum. Background technique [0002] The application and demand of pumps in agriculture, industry and military is huge. Since the working environment is usually complex environments such as high pressure and high speed, pump failures occur frequently. The cause of cavitation is that the partial pressure of the liquid in the fluid machine is lower than the vaporization pressure at that temperature, resulting in cavitation. Pump cavitation will lead to unstable liquid flow, resulting in severe vibration and noise, which will affect the performance of the pump. In addition, the cavitation generated by cavitation will also damage the surface of the blade material and reduce the service life of the pump. [0003] There are many kinds of vibration excitation sources and strong noise in the working...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): F04D15/00
CPCF04D15/0088
Inventor 初宁吴大转余天义曹琳琳杨帅李倩倩
Owner ZHEJIANG UNIV
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