Characteristics of Externally Pressurized Porous Gas Bearings Considering Structure Permeability

Abstract

The performance of a finite length porous journal bearing fed by externally pressurized air is numerically analyzed in the present study. A quasi-linear numerical scheme associated with an underrelaxation factor is used to solve the pressure solutions of the nonlinear coupled partial differential equation (PDE). Two characteristic parameters, i.e., the feeding parameter Λp and a conventional bearing number Λ, are involved in the analysis. The results show that the aerodynamic lubricating effect is dominant for the porous bearing having a small Λp number, whereas the aerostatic effect prevails inside the bearing space as the Λp number is large. When the permeability parameter Λp is small, the aerodynamic effect is further promoted for the bearing operating at heavy load; herein the minimum film thickness becomes relatively small. It is found that a bearing with a small Λp will have a higher risk for the journal shaft to touch the bearing wall than a bearing with large Λp. Therefore, as far as the bearing safety and loading capacity are concerned, a porous journal bearing with Λp ranging between 0.5 and 1 is recommended in practical use.

KEY WORDS:

• Porous Bearings
• Permeability
• Externally Pressurized

Review led by Ted Keith