Steady-State Analysis of an Externally Pressurized Porous Gas Journal Bearing With Herringbone Grooves Considering Velocity Slip Effect

Abstract

Abstract. A novel externally pressurized porous gas journal bearing with herringbone grooves is proposed to provide a larger load-carrying capacity, especially under high compressibility number conditions. The steady-state performance of the proposed bearing is investigated systematically. Considering the Beavers–Joseph velocity slip boundary conditions at the film–bushing interface, the steady-state model of the porous gas journal bearing with herringbone grooves is established by using the boundary-fitted coordinate system and finite volume method. The Newton–Raphson method and the successive over-relaxation scheme are applied to solve the nonlinear equivalent modified Reynolds equation and the three-dimensional porous flow equation, respectively. The numerical model is then validated by comparing with the previously published data regarding the conventional porous gas journal bearing and the self-acting herringbone-groove gas journal bearing. The influence of slip effect, groove effect, and groove parameters on the steady-state performance of the bearing is analyzed under different operating conditions. The calculated result shows that, when the compressibility number Λ > 15 and the feeding parameter Λp < 2, the load capacity of the proposed bearing is much larger than that of the conventional type; but when Λ < 5, the conventional type might be superior for all practical Λp. The groove effect could lead to a reduction in the direct moment but an increase in the cross-coupled moment. Taking the slip effect into account, the load capacity and attitude angle of the bearing reduce by less than 10% and 4.5 deg, respectively. The effect of slip on the load capacity could become the most significant at approximately Λp = 2 corresponding to the maximum load capacity obtained without considering the slip effect. The optimum values of spiral angle and groove depth ratio corresponding to the maximum load capacity and minimum attitude angle are related to the feeding parameter.