Lubrication of epicyclic gear system for gas turbine engine
An epicyclic gear system includes a sun gear, a ring gear, and two or more star gear assemblies enmeshed between the sun gear and the ring gear. Each star gear assembly includes a star gear and a journal bearing supportive of the star gear. The journal bearing includes one or more lubricant passageways to deliver a flow of lubricant to a selected location of the star gear assembly, wherein a first cross-sectional area of a lubricant passage of a first journal bearing of the two or more star gear assemblies is greater than a second cross-sectional area of the corresponding lubricant passage of a second journal bearing of the two or more star gear assemblies.
1. An epicyclic gear system comprising:
a sun gear;
a ring gear; and
two or more star gear assemblies enmeshed between the sun gear and the ring gear, each star gear assembly including:
a star gear; and
a journal bearing supportive of the star gear;
wherein the journal bearing includes one or more lubricant passageways to deliver a flow of lubricant to a selected location of the star gear assembly, wherein a first cross-sectional area of a lubricant passage of a first journal bearing of the two or more star gear assemblies is greater than a second cross-sectional area of the corresponding lubricant passage of a second journal bearing of the two or more star gear assemblies; and
wherein the first journal bearing is positioned vertically higher than the second journal bearing.
2. The epicyclic gear system of claim 1 , wherein the one or more lubricant passageways includes:
an axially-extending lubricant passageway; and
a radially-extending lubricant passageway fluidly connected to the axially-extending lubricant passage.
3. The epicyclic gear system of claim 2 , wherein the first cross-sectional area is a cross-sectional area of the radially-extending lubricant passageway of the first journal bearing and the second cross-sectional area is a cross-sectional area of the radially-extending lubricant passageway of the second journal bearing.
4. The epicyclic gear system of claim 1 , wherein the selected location is an interface defined between a radial inner surface of the star gear and a radial outer surface of each journal bearing.
5. The epicyclic gear system of claim 1 , wherein each journal bearing is fluidly connected to a lubricant manifold.
6. The epicyclic gear system of claim 1 , further comprising a carrier to which the two or more star gear assemblies are coupled.
7. The epicyclic gear system of claim 1 , further comprising five star gear assemblies enmeshed between the sun gear and the ring gear.
8. The epicyclic gear system of claim 7 , wherein the cross-sectional areas of the lubricant passageways of the journal bearings varies with vertical position of the journal bearings in the epicyclic gear system.
9. A gas turbine engine comprising:
a fan section;
a compressor section;
a combustor section;
a turbine section; and
an epicyclic gear system to couple the fan section to the compressor section, the epicyclic gear system including:
a sun gear;
a ring gear; and
two or more star gear assemblies enmeshed between the sun gear and the ring gear, each star gear assembly including:
a star gear; and
a journal bearing supportive of the star gear;
wherein the journal bearing includes one or more lubricant passageways to deliver a flow of lubricant to a selected location of the star gear assembly, wherein a first cross-sectional area of a lubricant passage of a first journal bearing of the two or more star gear assemblies is greater than a second cross-sectional area of the corresponding lubricant passage of a second journal bearing of the two or more star gear assemblies; and
wherein the first journal bearing is positioned vertically higher than the second journal bearing.
10. The gas turbine engine of claim 9 , wherein the one or more lubricant passageways includes:
an axially-extending lubricant passageway; and
a radially-extending lubricant passageway fluidly connected to the axially-extending lubricant passage.
11. The gas turbine engine of claim 10 , wherein the first cross-sectional area is a cross-sectional area of the radially-extending lubricant passageway of the first journal bearing and the second cross-sectional area is a cross-sectional area of the radially-extending lubricant passageway of the second journal bearing.
12. The gas turbine engine of claim 9 , wherein the selected location is an interface defined between a radial inner surface of the star gear and a radial outer surface of each journal bearing.
13. The gas turbine engine of claim 9 , wherein each journal bearing is fluidly connected to a lubricant manifold.
14. The gas turbine engine of claim 9 , further comprising a carrier to which the two or more star gear assemblies are coupled.
15. The gas turbine engine of claim 9 , further comprising five star gear assemblies enmeshed between the sun gear and the ring gear.
16. The gas turbine engine of claim 15 , wherein the cross-sectional areas of the lubricant passageways of the journal bearings varies with vertical position of the journal bearings in the epicyclic gear system.
17. A method of providing a flow of lubricant to an epicyclic gear system comprising:
urging a flow of lubricant from a lubricant source toward the epicyclic gear system;
distributing the flow of lubricant to two or more star gear assemblies of the epicyclic gear system; and
flowing the flow of lubricant through a lubricant passageway disposed at a journal bearing of each star gear assembly of the two or more star gear assemblies;
wherein a first cross-sectional area of a lubricant passage of a first journal bearing of the two or more star gear assemblies is greater than a second cross-sectional area of the corresponding lubricant passage of a second journal bearing of the two or more star gear assemblies; and
wherein the first journal bearing is positioned vertically higher than the second journal bearing.
18. The method of claim 17 , further comprising lubricating an interface defined between a radial inner surface of a star gear and a radial outer surface of each journal bearing.