Investigation of thermohydrodynamic behaviour of gas foil journal bearing accounting slip-flow phenomenon

The use of gas foil bearings in turbomachines such as turbochargers and turboexpanders in recent times comes into picture due to merits of gas foil bearings over simple gas lubricated bearings. The high speed leads to various constraints in selection process of the bearings. However, gas foil bearing's (GFBs) ability to improve the dynamic characteristics (such as stiffness and damping) makes them hot topic to investigate. Usually, gas foil bearings deal with operating conditions such as high speed and low clearance region which further leads to slip-flow condition at solid-fluid interface. The current article investigates the hydrodynamics, thermal characteristics and thermohydrodynamics of the gas foil journal bearing (GFJB) under the impact of slip-flow condition. The mathematical model is formulated by considering first-order velocity slip and thus modifying the Reynold's equation coupled with the energy equation. The viscosity and density are evaluated as a function of temperature which again substituted in Reynold's equation to investigate the thermohydrodynamic characteristics of GFJB. The equations are further discretised using finite difference method and solved using successive over relaxation (SOR) methodology. The comparison is drawn between the performance parameters for both no-slip and slip-flow conditions.