Static and dynamic characteristics of long porous journal bearings: use of the brinkman-extended darcy model

Based on the Brinkman-extended Darcy model, the main objective of this paper is to predict theoretically the effects of viscous shear stresses on the static and dynamic characteristics of long porous journal bearings. The static and dynamic characteristics obtained from the model, as the value of permeability parameter (D approaches zero, give good agreement with those of a solid bearing and hence provide support for the present predictions. The results show that the influences of viscous shear stresses on the static performance and the stability limits of porous journal-bearing systems are apparent and not negligible. In comparison with those of the slip-flow model and the Darcy model, the viscous shear effects of our model significantly provide an increase in the load capacity and static attitude angle as well as a reduction in the friction parameter of long porous journal bearings. Moreover, the long bearing system using our model under small disturbances is more stable than those of the slip-flow and Darcy models; and the quantitative effects on the stability criterion are more pronounced for the low-upsilon and high-epsilon_s. cases.