Gas turbine engine with high speed low pressure turbine section and bearing support features

Patent metadata

Field	Value
Publication number	US-9835052-B2
Application number	US-201715478671-A
Country	US
Kind code	B2
Filing date	Apr 4, 2017
Priority date	Jan 31, 2012
Publication date	Dec 5, 2017
Grant date	Dec 5, 2017

Abstract

A gas turbine engine according to an example of the present disclosure includes, among other things, a fan, a compressor section, and a turbine section including a fan drive turbine and a second turbine. The fan drive turbine has a first exit area at a first exit point and is rotatable at a first speed. A mid-turbine frame is positioned intermediate the fan drive turbine and the second turbine, and can include a bearing support. The second turbine has a second exit area at a second exit point and is rotatable at a second speed. A first performance quantity is defined as the product of the first speed squared and the first area. A second performance quantity is defined as the product of the second speed squared and the second area.

First claim

What is claimed is:

1. A gas turbine engine comprising:
a fan having fewer than 26 fan blades;
a compressor section including a first compressor and a second compressor;
a turbine section including a fan drive turbine and a second turbine;
a gear system with a gear reduction, the fan drive turbine driving the fan through the gear system;
a mid-turbine frame positioned intermediate the fan drive turbine and the second turbine, and having a first bearing supporting a first shaft rotatable with the fan drive turbine in an overhung manner;
wherein the fan drive turbine has a first exit area at a first exit point and is rotatable at a first speed, the second turbine has a second exit area at a second exit point and is rotatable at a second speed, said first and second speeds being redline speeds; and
wherein a first performance quantity is defined as the product of the first speed squared and the first area, a second performance quantity is defined as the product of the second speed squared and the second area, and a performance ratio of the first performance quantity to the second performance quantity is between 0.5 and 1.5.

2. The gas turbine engine as set forth in claim 1 , wherein the fan drive turbine is a 3-stage to 6-stage turbine, and the second turbine is a 2-stage turbine.

3. The gas turbine engine as set forth in claim 2 , wherein the first compressor has 3 stages.

4. The gas turbine engine as set forth in claim 2 , wherein the mid-turbine frame includes a guide vane positioned intermediate the fan drive turbine and the second turbine.

5. The gas turbine engine as set forth in claim 4 , wherein the performance ratio is equal to or greater than 0.8.

6. The gas turbine engine as set forth in claim 5 , wherein the mid-turbine frame includes a plurality of airfoils in a core airflow path.

7. The gas turbine engine as set forth in claim 6 , wherein the performance ratio is greater than or equal to 1.0.

8. The gas turbine engine as set forth in claim 7 , wherein the gear system is a planetary gear system.

9. The gas turbine engine as set forth in claim 7 , wherein the mid-turbine frame has a second bearing supporting an outer periphery of a second shaft rotatable with the second turbine.

10. The gas turbine engine as set forth in claim 9 , wherein the gear system is intermediate the fan drive turbine and the first compressor such that the fan and the first compressor are rotatable at a common speed.

11. The gas turbine engine as set forth in claim 5 , wherein the performance ratio is less than or equal to 1.075.

12. The gas turbine engine as set forth in claim 5 , wherein the second speed is greater than twice the first speed.

13. The gas turbine engine as set forth in claim 1 , comprising:
a fan drive shaft interconnecting the gear system and the fan;
a frame supporting at least a portion of the fan drive shaft, the frame defining a frame transverse stiffness;
a flexible support at least partially supporting the gear system, the flexible support defining a support transverse stiffness with respect to the frame transverse stiffness; and
wherein the support transverse stiffness is less than 50% of the frame transverse stiffness.

14. The gas turbine engine as set forth in claim 1 , wherein the gear system is straddle-mounted by bearings.

15. The gas turbine engine as set forth in claim 14 , comprising:
a fan drive shaft interconnecting the gear system and the fan;
a frame supporting at least a portion of the fan drive shaft, the frame defining a frame transverse stiffness and a frame lateral stiffness;
a flexible support at least partially supporting the gear system, the flexible support defining a support transverse stiffness with respect to the frame transverse stiffness and a support lateral stiffness with respect to the frame lateral stiffness;
wherein the support transverse stiffness is less than 80% of the frame transverse stiffness; and
wherein the support lateral stiffness is less than 80% of the frame lateral stiffness.

16. The gas turbine engine as set forth in claim 15 , wherein the support transverse stiffness is less than 50% of the frame transverse stiffness, and the support lateral stiffness is less than 50% of the frame lateral stiffness.

17. The gas turbine engine as set forth in claim 16 , wherein the support transverse stiffness is less than 20% of the frame transverse stiffness.

18. The gas turbine engine as set forth in claim 17 , wherein the support lateral stiffness is less than 20% of the frame lateral stiffness.

19. The gas turbine engine as set forth in claim 18 , wherein the second speed is greater than twice the first speed.

20. The gas turbine engine as set forth in claim 19 , wherein the performance ratio is less than or equal to 1.075.

21. A gas turbine engine comprising:
a fan having fewer than 26 fan blades;
a turbine section including a fan drive turbine and a second turbine;
a gear system with a gear reduction, the fan drive turbine driving the fan through the gear system;
a mid-turbine frame positioned intermediate the fan drive turbine and the second turbine;
wherein the mid-turbine frame includes a guide vane positioned intermediate the fan drive turbine and the second turbine;
wherein the fan drive turbine has a first exit area at a first exit point and is rotatable at a first speed, the second turbine has a second exit area at a second exit point and is rotatable at a second speed, said first and second speeds being redline speeds; and
wherein a first performance quantity is defined as the product of the first speed squared and the first area, a second performance quantity is defined as the product of the second speed squared and the second area, and a performance ratio of the first performance quantity to the second performance quantity is between 0.8 and 1.5.

22. The gas turbine engine as set forth in claim 21 , wherein the fan drive turbine and second turbine are rotatable in opposed directions, and the guide vane is an air turning guide vane.

23. The gas turbine engine as set forth in claim 22 , wherein the mid-turbine frame has a first bearing supporting a first shaft rotatable with the fan drive turbine in an overhung manner.

24. The gas turbine engine as set forth in claim 23 , wherein the fan drive turbine is a 3-stage to 6-stage turbine, and the second turbine is a 2-stage turbine.

25. The gas turbine engine as set forth in claim 22 , wherein the fan drive turbine is a 3-stage to 6-stage turbine, and the second turbine is a 2-stage turbine.

26. The gas turbine engine as set forth in claim 25 , wherein the fan drive turbine is a 3-stage turbine.

27. The gas turbine engine as set forth in claim 25 , comprising:
a fan drive shaft interconnecting the gear system and the fan;
a frame supporting at least a portion of the fan drive shaft, the frame defining a frame transverse stiffness;
a flexible support at least partially supporting the gear system, the flexible support defining a support transverse stiffness with respect to the frame transverse stiffness; and
wherein the support transverse stiffness is less than 50% of the frame transverse stiffness.

28. The gas turbine engine as set forth in claim 25 , wherein the performance ratio is greater than or equal to 1.0.

29. The gas turbine engine as set forth in claim 28 , wherein the second speed is greater than

Assignees

• United Technologies Corp

Inventors

• Schwarz Frederick M
• Suciu Gabriel L
• Ackermann William K
• Kupratis Daniel Bernard
• Mccune Michael E

Classifications

• F05D2240/60

  Shafts · CPC title

• F04D29/325

  for axial flow fans (blade mountings F04D29/34, blades F04D29/38) · CPC title

• F04D19/02

  Multi-stage pumps · CPC title

• F05D2220/32

  in gas turbines · CPC title

• F02C3/04

  having a turbine driving a compressor (power transmission arrangements F02C7/36; control of working fluid flow F02C9/16) · CPC title