A practical optical fiber reflective sensor model of measuring oil film thickness for thrust bearing

An overall and systematical study for optical fiber sensor of measuring oil film thickness in thrust bearing is introduced. On the basis of experiment results of the effect from temperature and pressure of lubrication oil to oil film thickness, a new kind of optical fiber sensor mathematical model of measuring oil film thickness that forms double concentric rings around emitter is set up. The outputs of this compensated kind of optical fiber sensor are independent of the characteristics of the light source, of the losses in the ambient medium and target reflectivity. In addition, the distance information is averaged over several receivers on the target surface, which reduces signal fluctuations due to in homogeneities. An actual measurement was made with HEC thrust bearing and the results were in good agreement with theoretical calculations.