Tribology of high speed aerodynamic foil journal bearings

Foil journal bearings come under the category of air lubricated journal bearings where the lubricant is atmospheric air. In this type of bearings the pressure developed is due to the aerodynamic wedge developed between the rotating shaft mid the foil bearing surface. This paper is concerned with the analysis of the bending dominated type foil beariug, in which the compliance is effected mainly through the bending of foils. The nonlinear Reynolds equation has been used for the aerodynamic pressure solution. Effect of clastohydrodynamics on foil jourcril bcarinOris been studied. The problem has been formulated usirt; incretneAil finite' clement method. Two types of bending dominated foil bearings have been considered for analysis, namely straight foil type and curved foil type bearings. The equations for the dynamic coefficients were obtained by a perturbation technique and the results were computed using the finite element method. The effect of bearing compliance and the bearing number on performance parameters has been studied, the results were compared with the available literature.