Basic Study on Simultaneous Measurement of Oil Film Thickness and Oil Film Temperature Using Dual Fluorescence Method

Abstract

A new method has been investigated for the simultaneous measurement of oil film thickness and temperature by using fluorescence technique, which was proposed by Azetsu et. al.⁽⁴⁾. The capability of oil film temperature measurement was confirmed by the precise calibration in the range from room temperature to 180°C with Coumarin 6 and Rhodamine B, which were dyes of different wavelength and of different dependence of intensity with temperature. The absorption by Rhodamine B was found out to influence the dependence of fluorescence intensity of Coumarin 6 with temperature. Consequently, the concentration ratio of dyes can be determined in which the fluorescence intensity was least affected by temperature. Based on the investigation, Laser Induced Fluorescence system was extended to measure the oil film thickness and temperature simultaneously with dual equipments for measuring fluorescence intensity of different wavelength range. The system was applied to the measurement of piston oil film in real operating conditions, which provided reasonable results for the oil film temperature on the piston top land.