Flexible support structure for a geared architecture gas turbine engine
A gas turbine engine includes a fan shaft that drives a fan that has fan blades. The fan delivers airflow to a bypass duct. A gear system is connected to the fan shaft and is driven through an input defining an input lateral stiffness and an input transverse stiffness. A gear system flex mount arrangement accommodates misalignment of the fan shaft and the input during operation. A frame for supporting the fan shaft defines a frame lateral stiffness and a frame transverse stiffness. The input lateral stiffness is less than 11% of the frame lateral stiffness and the input transverse stiffness is less that 11% of the frame transverse stiffness.
1. A gas turbine engine, comprising:
a fan shaft driving a fan having fan blades, wherein the fan delivers airflow to a bypass duct;
a gear system connected to said fan shaft and driven through an input defining an input lateral stiffness and an input transverse stiffness, said gear system includes a gear mesh defining a gear mesh lateral stiffness;
a gear system flex mount arrangement, wherein said gear system flex mount arrangement accommodates misalignment of said fan shaft and said input during operation; and
a frame for supporting said fan shaft defining a frame lateral stiffness and a frame transverse stiffness, wherein said input lateral stiffness is less than 11% of said frame lateral stiffness and less than 5% of said gear mesh lateral stiffness.
2. The gas turbine engine of claim 1 , wherein said gear system includes a ring gear defining a ring gear lateral stiffness that is less than 12% of said gear mesh lateral stiffness.
3. The gas turbine engine of claim 2 , wherein said gear system flex mount arrangement further includes a flexible support defining a flexible support transverse stiffness and said flexible support transverse stiffness is less than 11% of said frame transverse stiffness.
4. The gas turbine engine of claim 3 , further comprising a two stage high pressure turbine and the bypass duct is at least partially defined by a housing outward of the fan.
5. The gas turbine engine of claim 4 , wherein said flexible support define a flexible support lateral stiffness that is less than 11% of said frame lateral stiffness.
6. The gas turbine engine of claim 1 , wherein said gear system includes a ring gear defining a ring gear transverse stiffness and said gear mesh define a gear mesh transverse stiffness and said ring gear transverse stiffness is less than 12% of said gear mesh transverse stiffness.
7. The gas turbine engine of claim 6 , wherein said input transverse stiffness is less than 5% of said gear mesh transverse stiffness.
8. The gas turbine engine of claim 2 , wherein said ring gear define a ring gear transverse stiffness and said gear mesh defines a gear mesh transverse stiffness and said ring gear transverse stiffness is less than 12% of said gear mesh transverse stiffness.
9. The gas turbine engine of claim 1 , wherein said gear system flex mount arrangement includes a flexible support defining a flexible support lateral stiffness that is less than 11% of said frame lateral stiffness.
10. The gas turbine engine of claim 9 , wherein said gear mesh define a gear mesh transverse stiffness, and said input transverse stiffness is less than 5% of said gear mesh transverse stiffness.
11. The gas turbine engine of claim 10 , wherein said gear system includes a ring gear defining a ring gear lateral stiffness less that 12% of said gear mesh lateral stiffness.
12. A gas turbine engine, comprising:
a fan shaft driving a fan having fan blades, wherein the fan delivers airflow to a bypass duct;
a gear system drivingly connected to said fan shaft, said gear system includes a ring gear defining a ring gear lateral stiffness and a gear mesh defining gear mesh lateral stiffness and a gear mesh transverse stiffness;
a flexible support defining a flexible support lateral stiffness and a flexible support transverse stiffness; and
wherein said ring gear lateral stiffness is less than 12% of said gear mesh lateral stiffness and at least one of said flexible support lateral stiffness and said flexible support transverse stiffness is less than 8% of a respective one of said gear mesh lateral stiffness and said gear mesh transverse stiffness.
13. The gas turbine engine of claim 12 , wherein said flexible support transverse stiffness is less than 8% of said gear mesh transverse stiffness.
14. The gas turbine engine of claim 13 , wherein said flexible support lateral stiffness is less than 8% of said gear mesh lateral stiffness.
15. The gas turbine engine of claim 12 , wherein a fan shaft support defines a fan shaft support lateral stiffness and a fan shaft support transverse stiffness and at least one of said flexible support lateral stiffness and said flexible support transverse stiffness is less than 11% of a respective one of said fan shaft support lateral stiffness and said fan shaft support transverse stiffness.
16. The gas turbine engine of claim 15 , wherein said flexible support transverse stiffness is less than 11% of said fan shaft support transverse stiffness.
17. The gas turbine engine of claim 16 , wherein the flexible support lateral stiffness is less than 11% of said fan shaft support lateral stiffness.
18. The gas turbine engine of claim 17 , wherein said flexible support lateral stiffness and said flexible support transverse stiffness are less than 8% of a respective one of said gear mesh lateral stiffness and said gear mesh transverse stiffness.
19. The gas turbine engine of claim 12 , further comprising a two stage high pressure turbine and the bypass duct is at least partially defined by a housing outward of the fan.
20. A gas turbine engine, comprising:
a fan shaft driving a fan having fan blades, wherein the fan delivers airflow to a bypass duct;
a frame supporting said fan shaft and defining a frame lateral stiffness and a frame transverse stiffness;
a gear system connected to said fan shaft and driven through an input wherein said input to said gear system defines an input lateral stiffness; and
a gear system flex mount arrangement, wherein said flex mount arrangement accommodates misalignment of said fan shaft and said input during operation and includes a flexible support defining a flexible support lateral stiffness and a flexible support transverse stiffness and the flexible support lateral stiffness is less than 11% of said frame lateral stiffness and the flexible support transverse stiffness is less than 11% of said frame transverse stiffness.
21. The gas turbine engine of claim 20 , wherein said gear system includes a gear mesh defining a gear mesh lateral stiffness and said flexible support lateral stiffness is less than 8% of said gear mesh lateral stiffness.
22. The gas turbine engine of claim 21 , wherein said gear system includes a ring gear defining a ring gear lateral stiffness that is less than 12% of said gear mesh lateral stiffness.
23. The gas turbine engine of claim 22 , wherein said gear mesh defines a gear mesh transverse stiffness, and said flexible support transverse stiffness is less than 8% of said gear mesh transverse stiffness.
24. The gas turbine engine of claim 23 , wherein said ring gear defines a ring gear transverse stiffness and said ring gear transverse stiffness is less than 12% of said gear mesh transverse stiffness.
25. The gas turbine engine of claim 24 , further comprising a two stage high pressure turbine and the bypass duct is at least partially defined by a housing outward of the fan.
26. The gas turbine engine of claim 22 , wherein said input lateral stiffness is less than 5% of said gear mesh lateral stiffness.
27. The gas turbine engine of claim 26 , further comprising a journal bearing defining a journal bearing lateral stiffness that is less than said gear mesh lateral stiffness.