SQUEEZE FILM BEHAVIOR IN A HEMISPHERICAL POROUS BEARING USING THE BRINKMAN MODEL

On the basis of the Brinkman model, the main objective of this paper i s to theoretically predict the effects of viscous shear stresses on th e pure squeeze film behavior in a hemispherical porous bearing under a constant load. The modified Reynolds equation is derived by using the Brinkman equations to account for the viscous shear effects. Accordin g to the results, the influence of viscous shear stresses on the squee ze film characteristics is significant and not negligible. It is also found that the Brinkman model predicts a quite different squeeze film action than those derived by the Darcy model and the slip-flow model. Compared with that derived by the Darcy model for thin-walled porous b earings, the viscous shear effects of the Brinkman model reduce the lo ad capacity and the response time of the squeeze film, but the viscous shear effects increase the load capacity and lengthen the response ti me of the squeeze film action for rotor-bearing contact to occur as co mpared to that of the slip-flow model. Moreover, by considering the vi scous shear effects and the bearing thickness ratio, the Brinkman mode l provides an appropriate prediction of the squeeze film characteristi cs for a wide range of the porous bearing thickness.