Original Article

Characteristics of pressure signal of oil pulsating flow based on wavelet analysis

¹ School of Mechanical & Electrical, Hebei Key Laboratory of Safety Monitoring of Mining Equipment, North China Institute of Science and Technology, Hebei, 065201, PR China
² Heibei Key Laboratory of Hazardous Chemicals Safety and Control Technology, School of Chemical and Environmental Engineering, North China Institute of Science and Technology, Hebei, 065201, PR China

^* e-mail: lycy@ncist.edu.cn

Received: 11 July 2025
Accepted: 4 October 2025

Abstract

An analytical investigation was undertaken to explore the dynamics of pressure signals, focusing on the energy density, energy spectrum, and distribution of vibration energy over time. The analysis incorporated various parameters, including the real part of wavelet coefficients, their magnitude, square values, and variance. The findings indicate the effectiveness of the real part of the wavelet coefficients in capturing the periodic nature of oil pulsating flow. As the scale of wavelet decomposition decreases, the region of periodic changes concomitantly diminishes. It is evident that the periodicity of the pulsating flow becomes more pronounced as the modulus of the wavelet coefficients increases. The oil pressure signal displays five primary periods and exhibits significant modulation characteristics, locality, and discontinuity. It is evident that as the decomposition scale, which is directly related to the primary period increases, there is a concurrent decrease in the vibration frequency of pressure signal. This relationship can be expressed in exponentially decreasing, approximately following a 2:1 ratio. This study quantifies an energy-weighted five-period hierarchy for transformer-oil pulsation and to validate it with synchronous vibration-corrected measurements, to establish a correlation between the oil pressure signal and its vibration characteristics, providing substantial support for research on oil pollution control.