Observation of Oil Film Behavior in Oil Film Rupture Region on Journal Bearings utilizing Photochromic Visualization Technique

Abstract

The oil film behavior in a journal bearing was observed utilizing a photochromism visualization technique that uses an oil film that changes color when irradiated with ultraviolet light as a tracer. This method is an innovative technique that enables simultaneous measurement of oil film flow and oil film thickness. In the end-expanded gap of a journal bearing, a gas-phase region is generated due to negative pressure and the drawing in of air. Since cavitation greatly affects bearing performance depending on its condition, it is important to understand it by direct observation of the bearing surface. In this study, a sapphire journal bearing with a transparent surface was used for observation. By coloring the inside of the gas phase, it was possible to simultaneously observe the oil film that stays on the bearing surface and the oil film that moves with the shaft. From the difference in the thickness of the oil film on the bearing surface and the shaft side, the location of the gas phase can be determined.