Single- and dual-fiber fluorescence probes have been utilized to study oil-film behavior in a firing Diesel engine. A detailed analysis of the response characteristics of these probes was performed, and universal response curves have been generated through identification of the appropriate nondimensional parameters. For single-fiber probes a single curve was obtained, and for dual-fiber probes families of curves were identified based on three geometric dimensionless parameters. The complementary response characteristics of the single- and dual-fiber probes allows determination of the oil distribution within the piston–liner gap. The dual-fiber probe is not sensitive at small distances. Thus its signal originates solely from the piston surface, whereas the single-fiber probe is most sensitive at small distances and hence to the wall oil film. The engine data from the dual-fiber probe confirmed the presence of an oil film on the piston and provided a means of quantifying the transport of this oil within the engine.
© 2000 Optical Society of America
Original Manuscript: November 1, 1999
Revised Manuscript: June 26, 2000
Published: October 20, 2000
Jaal B. Ghandhi, "Single- and dual-fiber fluorescence probes: application to oil-film measurements in an internal combustion engine," Appl. Opt. 39, 5456-5464 (2000)