CFD simulation of water lubricated conical hydrodynamic journal bearings

Abstract

In concern with the environmental impact of lubricating fluids, water-lubricated bearings have been preferred and recommended instead of conventional oil-lubricated bearingsin food and pharmaceutical industries. Conical hydrodynamic journal bearing with having the ability to support the load in radial as well as in axial direction is beneficial to use in rotating machines, i.e. turbine, compressor etc. Performance of the conical hydrodynamic journal bearing depends on many operational parameters such as aspect ratio, semi cone angle, clearance ratio, eccentricity ratio and speed. At present Computational Fluid Dynamics (CFD) models are used as an alternative to experimental methods in research for overcoming the cost and operational difficulties. In this study conical hydrodynamic journal bearing have been investigated for aspect ratio (λ=0.5, 0.8, 1.0), semi cone angles (γ= 00, 50, 100, 200, 300), clearance ratio (e =0.001, 0.002) and speed (N = 2000, 5000, 10000 rpm) by using Ansys Fluent software. Fluid film pressure is one of the key operating parameters for describing the operating conditions of hydrodynamic journal bearings. Load carrying capacity, fluid film thickness and stability of bearing is evaluated based on pressure developed in clearance space of bearingwith rotation of journal. It was found that numerically simulated results of water lubricated conical journal bearing are influenced by the operational parameters of bearing. Present workis useful indesign ofcompact size conical hydrodynamic journal bearingfor combined radial and axial load application to replace two separate bearings i.e. journal and thrust.