Enhancing performance in water lubricated bearings with groove structures: a CFD analysis

Abstract

As the development of green tribology in marine industries has gained traction, there has been a gradual shift in the utilization of water-lubricated bearings over oil lubrication in stern tube bearings. Water lubricants are preferred in marine applications because of their availability, non-compressibility, and better frictional and cooling properties. In this study, a computational fluid dynamics (CFD) approach was employed to simulate the water film pressure distribution and additional water film characteristics to analyze the performance of water-lubricated bearings (WLB) under various operational conditions. The design parameters of the WLB were obtained from a commercially available axial groove bearing. To enhance the current bearing design and operational capability, it is imperative to understand the behavior of water-lubricated bearings through numerical techniques. An 8-axial V shaped groove structure with L/D ratios of 1, 1.5, and 2 was considered for simulating WLB behavior at four different journal speeds. The numerical results indicate that a notable increase in the maximum water film pressure and bearing load capacity was observed for WLBs simulated at higher operating speeds. At 4000 RPM, an increase of approximately 2.17% in peak positive pressures was noted for long WLBs than for lower speeds. In the groove domain, the water flow dynamics are considerably complex. A certain quantity of lubricant inflow descends into the groove regions and collides with the groove boundaries, resulting in a recirculation flow and vortices. The simulation results provide guidance for improving groove designs to further enhance the lubrication characteristics of axially grooved WLB.

Keywords

• Water lubricated bearings
• computational fluid dynamics
• water film pressures
• load capacity
• Tribology
• Fluid Mechanics