Static and Dynamic Characteristics of Externally Pressurized Porous Gas Journal Bearing With Four Degrees-of-Freedom

Abstract

This paper studies the static and dynamic coefficients of an externally pressurized porous gas journal bearing. The finite difference method is used to solve the Reynolds equation of the bearing to obtain the static load capacity. The linear perturbation method is adopted to derive the perturbation equations considering four degrees-of-freedom (4DOF), namely, the translational movements in x and y directions and the rotational movements around x and y directions. The effects of various parameters on the dynamic behaviors of the journal bearing are studied. These parameters include the bearing number, the supply pressure, the feeding parameter, the length-to-diameter ratio, the porosity parameter, the eccentricity ratio, and tilting angles. Simulated results prove that the proposed method is valid in estimating the static and dynamic characteristics of a porous gas journal bearing with 4DOF.

Investigations of the static and dynamic characteristics of the precision hydrostatic spindle with mid-thrust bearing under different loads

“…Secondly, the dimensionless coefficients of the dynamic characteristics of each bearing can be calculated by integrating transient pressure .1em p ¯ ζ false( θ , z ¯ , t false) across the oil film at the coupled journal and thrust bearings. Furthermore, the total stiffness K false¯ of the spindle is the sum of the stiffnesses of the bearings as follows 19,20 : where K ¯ jr , .1em K ¯ jl , .1em K ¯ tr , .1em and .1em K ¯ tl represent the journal and thrust bearing stiffness matrices on the left and right sides, respectively.…”

“…Secondly, the dimensionless dynamic characteristics coefficients of each bearing can be calculated by integrating transient pressure 𝑝𝑝̅ 𝜁𝜁 (𝜃𝜃, 𝑧𝑧̅ , 𝑡𝑡) across the oil film of the coupled journal and thrust bearings. Further, the total stiffness 𝐾𝐾 � of the spindle is the sum of the stiffness of each bearing as follows [20,21] :…”

A novel transient computational fluid dynamics-fluid–structure interaction model for the pad adaptive motion and rotordynamic coefficients of hybrid porous tilting pad bearings

“…The effects of a surface–restricted porous layer on the bearing characteristics were investigated using porous graphite and metal materials. Jiang et al 7 considered rotor tilting motion and developed Reynolds equations for porous journal bearings with four degrees of freedom. Further, to consider the velocity slip at the interface between the fluid film and porous restrictor, Elsharkawy and Guedouar 8 introduced the stress jump boundary condition to couple the Darcy equations in the porous region and the Stokes equations in the fluid film.…”

Effect of angular misalignment on the dynamic characteristics of externally pressurized air journal bearing

“…Although some articles have studied the dynamic characteristics of hydrodynamic bearings considering the rotating motion of the rotor, their researches cannot be fully applied to the externally pressurized air bearing compensated by orifices. [16][17][18][19] Recently, Xu and Jiang 20 investigated the dynamic characteristics of a motorized spindle with externally pressurized air bearings, which considered 5-DOF of the rotorbearing system. The FDM and perturbation method were used to solve the Reynolds equation, and the effect of rotating speed and tilt angle on the dynamic stiffness coefficients and damping coefficients of the air bearing was studied.…”