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 (h), inlet nozzle Reynolds number (Re), and geometrical aspect ratio (e) 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 h, Re, and e. Re and e have a great influence on the size and amount of vortices, and h has slight effects on the size of the vortices. The lengths of primary, secondary, and tertiary isolated vortices have a linear relationship with h. The lengths of the primary and secondary isolated vortices increase linearly with ascending e as e is small. But when Re and e are large enough, the size of the three vortices decreases