VMD analysis of pulsating flow pressure signal of oil with different particle concentration

Abstract

The Variational Mode Decomposition (VMD) method was used to decompose the oil pressure signals containing different particle concentrations; the number of components of VMD decomposition is determined by using the criterion of joint comparison between the slope of the center frequency of each component and the main frequency of the component of VMD decomposition, and a method for determining the main components of the signal is proposed by the average energy value; the Hilbert envelope demodulation analysis was carried out for the maximum energy component of each pressure signal. The results showed that the larger the particle concentration in the oil, the greater the number of main components obtained by VMD decomposition, and the proportion of the main components per unit concentration showed a monotonically decreasing trend. The main frequency of the main component is the fundamental frequency of its signal or the multiplication frequency combined with the rotating shaft frequency; there is an amplitude modulation relationship between any components; with the increase of particle concentration, the fundamental frequency of the pressure signal decreases successively; the maximum energy component of each pressure signal has the characteristics of amplitude modulation and frequency modulation in different degrees.