FLEXIBLE SUPPORT STRUCTURE FOR A GEARED ARCHITECTURE GAS TURBINE ENGINE
A gas turbine engine includes a fan shaft is drivingly connected to a fan having fan blades. A gear system is connected to the fan shaft and driven through an input having a gear reduction ratio of greater than 2.3. A gear system flex mount arrangement accommodates for misalignment of the fan shaft and the input during operation and includes a gear mesh defining a gear mesh transverse stiffness and a ring gear defining a ring gear transverse stiffness that is less than 20% of the gear mesh transverse stiffness. A bypass ratio is greater than ten (10). A fan pressure ratio is less than 1.45 measured across the fan blades alone. A low pressure turbine with an inlet, an outlet, and a low pressure turbine pressure ratio greater than 5:1. The low pressure turbine pressure ratio is a ratio of a pressure measured prior to the inlet as related to a pressure at the outlet prior to any exhaust nozzle.
1 . A gas turbine engine, comprising:
a fan shaft drivingly connected to a fan, said fan having fan blades;
a gear system connected to said fan shaft and driven through an input, said gear system having a gear reduction ratio of greater than 2.3;
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 gear mesh defining a gear mesh transverse stiffness and a ring gear defining a ring gear transverse stiffness that is less than 12% of said gear mesh transverse stiffness;
a bypass ratio greater than ten (10);
a fan pressure ratio of less than 1.45 measured across said fan blades alone; and
a low pressure turbine with an inlet, an outlet, and a low pressure turbine pressure ratio greater than 5:1, wherein said low pressure turbine pressure ratio is a ratio of a pressure measured prior to said inlet as related to a pressure at said outlet prior to any exhaust nozzle.
2 . The gas turbine engine of claim 1 , further comprising a two stage high pressure turbine.
3 . The gas turbine engine of claim 2 , wherein said ring gear defines a ring gear lateral stiffness, said gear mesh defines a gear mesh lateral stiffness, and said ring gear lateral stiffness is less than 12% of said gear mesh lateral stiffness.
4 . The gas turbine engine of claim 3 , wherein said gear system flex mount arrangement further includes a flexible support defining a flexible support lateral stiffness that is less than 8% of said gear mesh lateral stiffness.
5 . The gas turbine engine of claim 4 , wherein said gear system flex mount arrangement further includes a frame supporting said fan shaft defining a frame lateral stiffness and said flexible support lateral stiffness is less than 11% of said frame lateral stiffness.
6 . The gas turbine engine of claim 5 , wherein said flexible support defines a flexible support transverse stiffness, said gear mesh defines a gear mesh transverse stiffness, said frame defines a frame transverse stiffness, and said flexible support transverse stiffness is less than 8% of said gear mesh transverse stiffness and less than 11% of said frame transverse stiffness.
7 . The gas turbine engine of claim 6 , further comprising a fan tip speed of less than 1150 ft/second.
8 . The gas turbine engine of claim 6 , wherein said gear system is positioned between said fan and a low pressure compressor.
9 . The gas turbine engine of claim 8 , wherein said gear system flex mount arrangement further includes said input defining an input lateral stiffness, wherein said input lateral stiffness is less than 11% of said frame lateral stiffness.
10 . The gas turbine engine of claim 6 , wherein said ring gear defines a ring gear lateral stiffness that is less than 12% of said gear mesh lateral stiffness.
11 . The gas turbine engine of claim 10 , further comprising a fan tip speed of less than 1150 ft/second.
12 . The gas turbine engine of claim 1 , wherein said gear system flex mount arrangement further includes a frame supporting said fan shaft defining a frame transverse stiffness, wherein said flexible support defines a flexible support transverse stiffness that is less than 20% of said frame transverse stiffness.
13 . The gas turbine engine of claim 12 , wherein said ring gear defines a ring gear lateral stiffness, said gear mesh defines a gear mesh lateral stiffness, and said ring gear lateral stiffness is less than 12% of said gear mesh lateral stiffness.
14 . The gas turbine engine of claim 13 , wherein said flexible support defines a flexible support lateral stiffness, said frame defines a frame lateral stiffness, and said flexible support lateral stiffness is less than 11% of said frame lateral stiffness.
15 . The gas turbine engine of claim 14 , further comprising a two stage high pressure turbine.
16 . The gas turbine engine of claim 15 , wherein said flexible support transverse stiffness is less than 11% of said frame transverse stiffness.
17 . The gas turbine engine of claim 16 , wherein said gear system flex mount arrangement further includes said input defining an input lateral stiffness, wherein said input lateral stiffness is less than 11% of said frame lateral stiffness.
18 . The gas turbine engine of claim 17 , wherein said flexible support lateral stiffness is less than 8% of said gear mesh lateral stiffness.
19 . The gas turbine engine of claim 18 , wherein said input defines an input transverse stiffness that is less than 11% of said frame transverse stiffness.
20 . The gas turbine engine of claim 19 , further comprising a fan tip speed of less than 1150 ft/second.
21 . The gas turbine engine of claim 20 , wherein said flexible support transverse stiffness is less than 8% of said gear mesh transverse stiffness.
22 . The gas turbine engine of claim 14 , wherein said flexible support lateral stiffness is less than 8% of said gear mesh lateral stiffness.
23 . The gas turbine engine of claim 22 , wherein said flexible support transverse stiffness is less than 8% of said gear mesh transverse stiffness.
24 . The gas turbine engine of claim 23 , further comprising a two stage high pressure turbine.
25 . The gas turbine engine of claim 24 , further comprising a fan tip speed of less than 1150 ft/second.
26 . A gas turbine engine, comprising:
a fan shaft drivingly connected to a fan, said fan having fan blades;
a gear system connected to said fan shaft and driven through an input; 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 frame supporting said fan shaft and defining a frame lateral stiffness, and said input defining an input lateral stiffness that is less than 11% of said frame lateral stiffness.
27 . The gas turbine engine of claim 26 , wherein said frame defines a frame transverse stiffness and said input defines an input transverse stiffness that is less than 11% of said frame transverse stiffness.
28 . The gas turbine engine of claim 27 , wherein said gear system includes a gear mesh, and said gear system flex mount arrangement further includes said gear mesh defining a gear mesh lateral stiffness and a ring gear defining a ring gear lateral stiffness that is less than 12% of said gear mesh lateral stiffness.
29 . The gas turbine engine of claim 28 , wherein said gear system flex mount arrangement further includes a flexible support defining a flexible support transverse stiffness that is less than 20% of said frame transverse stiffness.
30 . The gas turbine engine of claim 29 , wherein said flexible support defines a flexible support lateral stiffness that is less than 20% of said frame lateral stiffness.