Study on a high-speed oil-free pump with fluid hydrodynamic lubrication

A novel centrifugal pump with axial directional inlet and outlet flow was presented. The system fluid was employed as the lubricant for the hydrodynamic bearings by which the pump can operate at the maximum speed of 8100 r/min without oil lubrication or rigid support. The performance curves related to the efficiency, head, and volume flow rate were obtained via a water cycle test rig. The efficiency at best efficiency point reached 36.14% with a volume flow rate of 4.13 m 3 /h and a head of 27.34 m at 7800 r/min. The maximum head reached 37.28 m, with a volume flow rate of 0.568 m 3 /h at 7800 r/min. The maximum volume flow rate of 6.05 m 3 /h was obtained with a head of 19.45 m at 8100 r/min. Then, the three-dimension computational fluid dynamics model with Reynolds-averaged Navier–Stokes equations and shear stress transport k- ω turbulence model for the pump and bearings was set up individually. The numerical results agreed well with the experimental data.