Geared turbine engine with relatively lightweight propulsor module
An example gas turbine engine includes a propulsor assembly including a fan and a fan drive turbine. A weight of the propulsor assembly is less than about 40% of a total weight of the gas turbine engine.
1. A gas turbine engine comprising:
a propulsor assembly consisting of a fan and a fan drive turbine, the fan including a hub and an array of fan blades extending from the hub;
a nacelle circumscribing the fan, wherein the propulsor assembly excludes the nacelle;
a bypass ratio of greater than 10;
a low fan pressure ratio of less than 1.45, the fan pressure ratio measured across the fan blades alone;
an epicyclic gear train defining a gear reduction ratio of greater than 2.6;
wherein a weight of the propulsor assembly is less than 40 percent of a total weight of the gas turbine engine, excluding the nacelle;
a high spool including a high pressure turbine;
an inner shaft concentric with an outer shaft, with the high spool comprising the outer shaft;
wherein the high pressure turbine is a two stage turbine, and the fan drive turbine is a three-stage or four-stage turbine;
wherein the fan drive turbine includes an inlet, an outlet, and a pressure ratio greater than 5:1, wherein the 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; and
wherein the fan comprises no more than 20 fan blades that fit within an annular fan case, and a ratio between a total number of the fan blades and a total number of turbine rotors of the fan drive turbine is between 3.3 and 8.6.
2. The gas turbine engine of claim 1 , further comprising a mid-turbine frame between the high pressure turbine and the fan drive turbine, wherein the mid-turbine frame includes a plurality of vanes that serve as inlet guide vanes for the fan drive turbine.
3. The gas turbine engine of claim 2 , wherein the weight of the propulsor assembly is 28.4 percent to 33.2 percent of a total weight of the gas turbine engine, excluding the nacelle.
4. The gas turbine engine of claim 3 , wherein the mid-turbine frame supports a bearing system.
5. The gas turbine engine of claim 4 , wherein the epicyclic gear train is a planetary gear system.
6. The gas turbine engine of claim 5 , wherein the fan blades include a composite material.
7. The gas turbine engine of claim 6 , further comprising tapered roller bearings, and wherein the fan drive turbine comprises directionally solidified blades.
8. The gas turbine engine of claim 7 , wherein the fan has a low corrected fan tip speed of less than 1150 ft/second.
9. The gas turbine engine of claim 1 , wherein the fan drive turbine is a four-stage turbine.
10. The gas turbine engine of claim 9 , wherein the fan blades include a composite material, and the fan has a low corrected fan tip speed of less than 1150 ft/second.
11. A gas turbine engine comprising:
a nacelle;
a propulsor assembly comprising a fan module and a turbine module, wherein the fan module excludes the nacelle, the fan module includes a fan having an array of fan blades, and the nacelle circumscribes the fan;
a bypass ratio of greater than 10;
a low fan pressure ratio of less than 1.45, the fan pressure ratio measured across the fan blades alone;
an epicyclic gear train defining a gear reduction ratio of greater than 2.6;
a mid-turbine frame including a plurality of vanes that serve as inlet guide vanes for the turbine module;
wherein a weight of the propulsor assembly is less than 40 percent of a total weight of the gas turbine engine, excluding the nacelle;
wherein the turbine module is a three-stage or four-stage turbine;
wherein the turbine module includes an inlet, an outlet, and a pressure ratio greater than 5:1, wherein the 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; and
wherein the fan comprises no more than 20 fan blades that fit within an annular fan case, and a ratio between a total number of the fan blades and a total number of turbine rotors of the turbine module is between 3.3 and 8.6.
12. The gas turbine engine of claim 11 , further comprising a two-stage high pressure turbine.
13. The gas turbine engine of claim 12 , wherein the weight of the propulsor assembly is less than 29.8 percent of the total weight of the gas turbine engine.
14. The gas turbine engine of claim 12 , wherein the mid-turbine frame is between the high pressure turbine and the turbine module, and the mid-turbine frame supports a bearing system.
15. The gas turbine engine of claim 14 , wherein the fan drive turbine is a four-stage turbine.
16. The gas turbine engine of claim 15 , further comprising tapered roller bearings.
17. The gas turbine engine of claim 15 , wherein the turbine module comprises directionally solidified blades.
18. The gas turbine engine of claim 17 , wherein the fan blades include a composite material.
19. The gas turbine engine of claim 18 , wherein the fan has a low corrected fan tip speed of less than 1150 ft/second.
20. The gas turbine engine of claim 19 , wherein the epicyclic gear train is a planetary gear system.
21. The gas turbine engine of claim 14 , wherein the fan drive turbine is a three-stage turbine.
22. The gas turbine engine of claim 21 , wherein the fan blades include a composite material, the fan has a low corrected fan tip speed of less than 1150 ft/second, and the epicyclic gear train is a planetary gear system.
23. A gas turbine engine comprising:
a propulsor assembly consisting of a fan and a fan drive turbine, the fan including a hub and an array of fan blades extending from the hub, and the fan blades including a composite material;
a nacelle circumscribing the fan, wherein the propulsor assembly excludes the nacelle;
a bypass ratio of greater than 10;
a low fan pressure ratio of less than 1.45, the fan pressure ratio measured across the fan blades alone;
an epicyclic gear train defining a gear reduction ratio of greater than 2.6;
wherein a weight of the propulsor assembly is about 28.4 percent to 33.2 percent of a total weight of the gas turbine engine, excluding the nacelle;
wherein the fan drive turbine is a three-stage or four-stage turbine;
wherein the fan drive turbine includes an inlet, an outlet, and a pressure ratio greater than 5:1, wherein the 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; and
wherein the fan comprises no more than 20 fan blades that fit within an annular fan case, and a ratio between a total number of the fan blades and a total number of turbine rotors of the fan drive turbine is between 3.3 and 8.6.
24. The gas turbine engine of claim 23 , wherein the epicyclic gear train is a planetary gear system.
25. The gas turbine engine of claim 24 , further comprising a two-stage high pressure turbine.
26. The gas turbine engine of claim 25 , further comprising a mid-turbine frame between the high pressure turbine and the fan drive turbine.
27. The gas turbine engine of claim 26 , wherein the mid-turbine frame has a plurality of vanes that serve as inlet guide vanes for the fan drive turbine.
28. The gas turbine engine of claim 27 , further comprising tapered roller bearings.
29. The gas turbine engine of claim 28 , wherein the fan drive turbine comprises directionally solidified blades.
30. The gas turbine engine of claim 29 , wherein the fan has a low corrected fan tip speed of less than 1150 ft/second.