Experimental analysis of the performances of oil filters in aero engines

摘要

This paper presents the results from an investigation on the mechanism of loading in the oil filters. The objectives of this study were targeting the understanding of the filter loading mechanisms and thus, quantification of their lives. Two models of flow at macro-level within the cartridge of the filter and at the micro-level within the pores of the three-layer paper of the filter were developed and run. The results were used to identify the maximum flow areas in the cartridge and flow velocity through the fibers. The experimental work was performed on commercial aircraft engine paper filters. Clean papers of the filter were scanned on 1 mm × 1 mm surfaces and mathematical models of the configuration of the fiber in the three folds were formulated. The entire filter surface was further generated by repetition of the scanner regions. Same type of loaded filter was disassembled and on specific determined surfaces, the particles were washed from the filter and preserved. The particles were measured and counted. The results analyzed in all three layers of the filter show that a 22 μm filter retained a population of particles ranging from 2 μm to 35 μm. The filtered particles are the ones circulating in the oil either as wear debris or as other types of impurities, and it is expected that particles with size larger than the size nomination of the filter are stopped. However, much smaller particles are equally retained by the filter. The results from this study are instrumental in the understanding of the mechanism of the filter loading and the wear particle distribution. The particle counting procedure employs biomedical techniques which represent a new approach to the area of experimental tribology.