Study on Mechanism of Lubrication in Porous Journal Bearings. Static Characteristics of Porous Journal Bearings With Open Ends at Start of Operation.

Abstract

A theoretical investigation of static characteristics at the start of operation is developed for a porous journal bearing with open ends lubricated only by the oil initially provided within its structures. Numerical results show that a negative pressure region exists in the porous matrix. Hence, air penetrates into the porous matrix both at the oil-film rupture zone in the clearance gap and at the porous ends of the bearing, which causes the reduction of oil content within the porous matrix. In the porous bearing with open ends, the angular extent of oil-film, the oil film force and the total leakage flow are smaller than those in the porous bearing with sealed ends. These static characteristics in the bearing with open ends are insignificantly affected by the eccentricity ratio as compared to those in the bearing with sealed ends. The experimental results show that the bearing with open ends yields a smaller amount of oil loss just after the start of the operation than the bearing with sealed ends, which qualitatively agrees with the theoretical prediction.