Vortices evolution in round pockets of modern machine tools

Abstract

Vortices evolutions in oil pockets of machine tools were investigated by using a particle image velocimetry (PIV) system and numerical simulations. The influences of Reynolds number (Re), aspect ratio of pocket depth‐to‐nozzle radius (e), and clearance height (h) on the vortices characteristics were studied. Up to three interacting vortices appear, namely, the primary vortex, the secondary vortex, and the tertiary vortex. The vortices evolve in a complex manner. The primary vortex appears at 15 < Re < 1610 and dominates the whole pocket flow at relatively high Re. The secondary vortex appears at Re > 210. The vortices size increases with e increasing. Moreover, the vortices detachment and reattachment positions were also been investigated. The vortices structures have significant influences on the distributions of pressures and wall shear stresses on the upper disc. The results further the understanding of vortices evolutions in oil pockets and will guide engineering applications related to the round pocket flow.