Particle erosion transient process visualization and influencing factors of the hydraulic servo spool valve orifice

Abstract

The erosion of the valve orifice can easily lead to the performance degradation of the hydraulic servo spool valve, which seriously affects the service life and reliability of the hydraulic servo system. In this paper, the erosion micro-morphological characteristics, erosive transient process visualization of solid particles, and factors affecting the erosion rate of the spool working edges were investigated. The results showed that there was a significant “edge collapse” phenomenon on the working edges of the spool, which was mainly characterized by surface peeling, notches, grooves, chamfers, and the radius of the fillet which fluctuated violently in the circumferential direction. The “smoothing, slipping, and somersaulting” evolution process started when the incident angle increased and the particles hit the valve orifice by a new visualization experiment model composed of the nozzle-baffle submerged jet. The erosion rate of the working edges also showed continuous fluctuations and violent changes, with strong scatter-like distribution characteristics. The erosion rate of the working edge in the up-flow field was approximately one time higher than that in the back-flow field. The erosion rate of the working edges increased as the oil viscosity and particle concentration increased. Under small openings, the impact frequency of particles and the working edge increased significantly. The distribution law of the erosion rate of the working edge agreed with the distribution characteristics of the erosion fillet radius of the working edges. The erosion rate variance was defined, which can be used to quantify the circular distribution of erosion rate. This study provides further understanding of the mechanism and influencing factors of the hydraulic servo spool valve erosion.