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Oil Scoop Designs to Improve Oil Distribution

IP.com Disclosure Number: IPCOM000247408D
Publication Date: 2016-Sep-02
Document File: 6 page(s) / 480K

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The IP.com Prior Art Database

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Oil Scoop Designs to Improve Oil Distribution

Background:

    Engine bearings require lubrication systems, to lubricate and cool the bearings during operation. For bearings that operate at higher speeds-for example, bearings in aircraft gas turbine engines-lubrication can be achieved through an "under race" lubrication system. The lubrication system can include one or more stationary nozzles and a rotating component called an "oil scoop," which is mounted on a rotating shaft. The rotating oil scoop captures the spray of oil jets from the stationary nozzles through a sequence of blades, trap zones, annular regions, weirs, axial slots, and holes, and delivers the oil to the bearings.

    The under race lubrication system is designed to ensure that oil flow captured by the oil scoop is distributed relatively uniformly to the bearings. However, some known oil scoop geometries exhibit undesirable non-uniformity of oil distribution (see Figures 1A and 1B). More specifically, at the exit of the oil scoop, the oil undergoes a sudden change in momentum, from a tangential direction to an axial direction due to the rectangular shape of a trap zone. With these designs, axial slots nearest to the end of the trap zone receive relatively more oil compared to other axial slots. The life of the bearings may be shortened, as the bearings are not receiving enough oil and/or are receiving too much oil.

FIGURE 1A:NON-UNIFORMITY OF OIL DISTRIBUTION IN KNOWN OIL SCOOP



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FIGURE 1B:ANALYSIS OF OIL DISTRIBUTION,KNOWN OIL SCOOP

Body:

    Several concepts to improve the oil distribution to the bearings are described herein. Figure 2 illustrates an oil scoop with a "helical" path.

FIGURE 2:OIL SCOOP WITH HELICAL PATH

    The helical design of the oil scoop eliminates the sudden tangential-to-axial momentum change of oil, between a trap zone and an annular reservoir. Indeed, due to the helical path of the oil scoop, the oil has a "smooth" transition into the annular reservoir, conserving most of the tangential momentum of the oil. The oil remains in the annular reservoir for a longer period of time, resulting in a smoother transition of the oil from the oil scoop to the axial slots. As shown

2

360° annular reservoir

Oil Flow Path


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in Figure 3, computational fluid dynamics (CFD) analysis shows improved uniformity of oil distribution from the oil scoop to the axial slots.

FIGURE 3:CFDANALYSIS OF OIL DISTRIBUTION,OIL SCOOP WITH HELICAL PATH

  As discussed above, non-uniform oil distribution in under race lubrication systems can result in overheating of bearing components in some areas with low oil flow, potentially reducing life of those bearings. This helical oil scoop design facilitates more uniform oil distribution to the bearings, improving heat convection by oil and thereby impr...