Numerical and Experimental Study of the Flow Field Structure Evolution in the Circular Recess of Oil Cavity

The laminar radial flow in the oil cavity of heavy-duty computer numerical control (CNC) machines is very complicated and has not been fully explored. Navier-Stokes equations have been applied through the whole flow region using finite volume approach to explore this complicated flow phenomenon, including the influences of the clearance height ( ), inlet nozzle Reynolds number (Re), and geometrical aspect ratio ( ) on flow behaviors. A fluid dynamic experiment has been conducted to study the flow structure by using particle image velocimetry (PIV). Numerical simulation results have been compared with the experimental results, finding a good agreement with the studied cases. The results suggest that there are complex vortices in the oil cavity. Flow field structure of the oil cavity largely depends on , Re, and . Re and have a great influence on the size and amount of vortices, and has slight effects on the size of the vortices. The lengths of primary, secondary, and tertiary isolated vortices have a linear relationship with . The lengths of the primary and secondary isolated vortices increase linearly with ascending as is small. But when Re and are large enough, the size of the three vortices decreases.