Test and analysis of self-excited pressure oscillations and noise in a hydraulic jet-pipe servo-valve

Self-excited high frequency pressure oscillations in the flow field of a hydraulic servo-valve are usually the source of high frequency noise. In this paper, by using a piezoelectric dynamic pressure transducer and a microphone, the self-excited high frequency pressure oscillations and noise in a hydraulic jet-pipe servo-valve are measured. The experiments are carried out when the supply pressures of the servo-valve are 11MPa and 20MPa respectively. In order to obtain more precise information, FFT and wavelet analysis are applied to resolve the tested pressure oscillation and noise signals into several basic wave signals. The possible causes of the self-excited high frequency oscillations and noise are predicted according to the analysis results. Based on the results, suggestions are given to reduce the pressure oscillations and noise in hydraulic servo-valves.