Particle motion and erosion morphology of the spool orifice in an electro-hydraulic servo valve under a small opening

Abstract

To explore the spool orifice’s particle motion and erosion morphology in an electro-hydraulic servo valve under a small opening, a modeled particle motion visualization test and CFD calculation were conducted to study typical particle trajectory. The influence of pressure differential, particle shape, and particle diameter on the erosion rate along the working edges was discussed. The erosion characteristic morphology and working edges’ fillet diameter distribution were measured and analyzed. There are four typical particle motions: translation and spin on the wall faced the flow, translation and turn on the backflow wall, carried motion by the mainstream and particle rotation in a vortex. A model of the erosive particle motion of the spool orifice was built based on the visualization test and CFD. During these motions, the microscopic scraping and collision of particles with the working edges are the main causes of erosion wear. The erosion wear rate of the working edge is proportional to the pressure differential and the non-roundness of the particles. The fillet of a working edge periodically increases or decreases with the circumferential angle, which occurs due to the morphology and is consistent with the erosion wear rate distribution along the working edge.