Geared turbofan gas turbine engine architecture
A gas turbine engine includes a very high speed low pressure turbine such that a quantity defined by the exit area of the low pressure turbine multiplied by the square of the low pressure turbine rotational speed compared to the same parameters for the high pressure turbine is at a ratio between about 0.5 and about 1.5.
1. A gas turbine engine comprising:
a fan section including less than 18 fan blades;
a gear train;
a compressor section;
a combustor in fluid communication with the compressor section;
a turbine section in fluid communication with the combustor and including a fan drive turbine and a second turbine, the fan drive turbine driving a fan rotor through the gear train wherein:
a power density greater than 1.5 lbf/in3 and less than or equal to 5.5 lbf/in3 wherein power density is defined as Sea Level Takeoff Thrust in lbf produced divided by a volume of the turbine section in cubic inches;
the fan drive turbine includes at least one rotor having a live rim radius (r) and a bore width (W), and a ratio of W/r is between 4.65 and 5.55;
the fan drive turbine has a first exit area and is configured to rotate at a first speed, the second turbine has a second exit area and is configured to rotate at a second speed, which is faster than the first speed, said first and second speeds being redline speeds, 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 greater than or equal to 0.8, and less than 1.5; and
the fan drive turbine has a number of fan drive turbine stages, and a ratio between the number of fan blades and the number of fan drive turbine stages is between 2.5 and 8.5.
2. The gas turbine engine set forth in claim 1 , wherein the power density is greater than or equal to 3.0 lbf/in3.
3. The gas turbine engine set forth in claim 2 , wherein the power density is greater than or equal to 4.0 lbf/in3.
4. The gas turbine engine set forth in claim 3 , wherein the performance ratio is greater than or equal to 1.0.
5. The gas turbine engine set forth in claim 1 , wherein the second turbine is a two stage turbine.
6. The gas turbine engine set forth in claim 5 , wherein the gear train is a planetary gear system.
7. The gas turbine engine set forth in claim 6 , further comprising a mid-turbine frame between the fan drive turbine and the second turbine, the mid-turbine frame supporting at least one bearing assembly and including at least one vane.
8. The gas turbine engine set forth in claim 1 , wherein the at least one rotor having a bore radius (R), and a ratio of r/R is between 2.00 and 2.30.
9. The gas turbine engine set forth in claim 8 , wherein the power density is greater than or equal to 3.0 lbf/in3.
10. The gas turbine engine set forth in claim 9 , wherein the power density is greater than or equal to 4.0 lbf/in3.
11. The gas turbine engine set forth in claim 1 , wherein the gear train is a planetary gear system.
12. A gas turbine engine comprising:
a fan section including a plurality of fan blades;
a gear train;
a compressor section;
a combustor in fluid communication with the compressor section;
a turbine section in fluid communication with the combustor and including a fan drive turbine and a second turbine, the fan drive turbine driving a fan rotor through the gear train wherein:
a power density greater than 1.5 lbf/in3 and less than or equal to 5.5 lbf/in3 wherein power density is defined as Sea Level Takeoff Thrust in lbf produced divided by a volume of the turbine section in cubic inches;
the fan drive turbine has a first exit area and is configured to rotate at a first speed, the second turbine has a second exit area and is configured to rotate at a second speed, which is faster than the first speed, said first and second speeds being redline speeds, 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 greater than or equal to 0.8 and less than or equal to 1.5; and
the fan drive turbine has a number of fan drive turbine stages, and a ratio between a number of said fan blades and a number of fan drive turbine stages is between 2.5 and 8.5.
13. The gas turbine engine set forth in claim 12 , wherein the plurality of fan blades is less than 18 fan blades.
14. The gas turbine engine set forth in claim 13 , wherein the gear train is a planetary gear system.
15. The gas turbine engine set forth in claim 14 , wherein the second turbine is a two stage turbine.
16. The gas turbine engine set forth in claim 13 , wherein the performance ratio is greater than or equal to 1.0.
17. The gas turbine engine set forth in claim 16 , wherein the first performance quantity is greater than or equal to 4.0.
18. The gas turbine engine set forth in claim 16 , wherein the gear train is a planetary gear train and the second turbine is a two stage turbine.
19. The gas turbine engine set forth in claim 18 , wherein the fan drive turbine includes at least one rotor having a live rim radius (r) and a bore width (W), and a ratio of W/r is between 4.65 and 5.55.
20. The gas turbine engine set forth in claim 19 , wherein the at least one rotor having a bore radius (R), and a ratio of r/R is between 2.00 and 2.30.
21. A gas turbine engine comprising:
a fan section including a plurality of fan blades;
a gear train;
a compressor section;
a combustor in fluid communication with the compressor section;
a turbine section in fluid communication with the combustor and including a fan drive turbine and a second turbine, the fan drive turbine driving a fan through the gear train wherein:
a power density greater than 1.5 lbf/in3 and less than or equal to 5.5 lbf/in3 wherein power density is defined as Sea Level Takeoff Thrust in lbf produced divided by the volume of the turbine section in cubic inches;
the fan drive turbine has a first exit area and is configured to rotate at a first speed, the second turbine has a second exit area and is configured to rotate at a second speed, which is faster than the first speed, said first and second speeds being redline speeds, 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 greater than or equal to 0.8 and less than or equal to 1.5; and
the fan drive turbine has a number of fan drive turbine stages, and a ratio between the number of fan blades and the number of fan drive turbine stages is between 2.5 and 8.5.
22. The gas turbine engine set forth in claim 21 , wherein the plurality of fan blades is less than 18 fan blades, the gear train is a planetary gear system, and the second turbine is a two stage turbine.
23. The gas turbine engine set forth in claim 21 , wherein the plurality of fan blades is less than 18 fan blades.
24. The gas turbine engine set forth in claim 23 , wherein the second turbine is a two stage turbine.
25. The gas turbine engine set forth in claim 23 , wherein the fan drive turbine includes at least one rotor having a live rim radius (r) and a bore width (W), and a ratio of W/r is between 4.65 and 5.55.
26. The gas turbine engine set forth in claim 21 , wherein the power density is greater than or equal to 3.0 lbf/in3.
27. The gas turbine engine set forth in claim 26 , wherein the power density is greater than or equal to 4.0 lbf/in3.
28. The gas turbine engine set forth in claim 21 , wherein the gear train is a planetary gear system.
29. The gas turbine engine set forth in claim 28 , wherein the power density is greater than or equal to 4.0 lbf/in3.
30. The gas turbine engine set forth in claim 21 , wherein the power density is greater than or equal to 3.0 lbf/in3.
31. The gas turbine engine set forth in claim 21 , wherein the gear train is a planetary gear system.