Static Characteristics of Journal Bearings under Starved Lubricating Conditions

Abstract

The static characteristics of journal bearings with an axial groove under starved lubrication are studied theoretically and a lubrication condition map is newly proposed. This map is represented using the contour map of the eccentricity ratio with the Sommerfeld number S in the horizontal axis and the dimensionless oil flow rate Qsup externally supplied in the vertical axis for the wide range of the operating conditions. It is found from the map that the eccentricity ratio increases with the decrease of Qsup. This tendency is more marked for a higher Sommerfeld number. Journal center loci show that the attitude angle decreases with Qsup. The degree of the starvation Λ and the oil supply rate Ψ are defined as the ratio of the dimensionless oil flow rate into the inlet of the oil film region to that obtained under the flooded lubrication condition and as the ratio of Qsup to Qsup* obtained under flooded lubrication conditions, respectively. The degree of starvation Λ varies with Ψ and the value of Λ can be determined by setting the value of Ψ. These facts suggest that the static characteristics and Λ are theoretically predicted once the value of Qsup or Ψ is determined.