GEARED TURBOFAN ENGINE WITH POWER DENSITY RANGE

1 . A gas turbine engine turbine comprising:

a high pressure turbine configured to rotate with a high pressure compressor as a high pressure spool in a first direction about a central axis;

a low pressure turbine configured to rotate with a low pressure compressor as a low pressure spool in said first direction about said central axis;

a power density that is greater than or equal to about 1.5 and less than or equal to about 5.5 lbf/in 3 ; and

a fan connected to the low pressure spool via a speed changing mechanism and will rotate in a second direction opposed to said first direction.

2 . (canceled)

3 . The engine as set forth in claim 1 , wherein said power density is greater than or equal to about 2.0.

4 . The engine as set forth in claim 3 , wherein said power density is greater than or equal to about 4.0.

5 . The engine as set forth in claim 1 , wherein said power density is calculated using a value that is sea level take-off, flat-rated static thrust.

6 . The engine as set forth in claim 5 , wherein guide vanes are positioned upstream of a first stage in said low pressure turbine to direct gases downstream of said high pressure turbine as they approach said low pressure turbine.

7 . The engine as set forth in claim 6 , wherein a mid-turbine frame supports said high pressure turbine.

8 . The engine as set forth in claim 7 , wherein said guide vanes are positioned intermediate said mid-turbine frame and said low pressure turbine.

9 . A gas turbine engine turbine comprising:

a high pressure turbine configured to rotate with a high pressure compressor as a high pressure spool in a first direction about a central axis;

a low pressure turbine configured to rotate with a low pressure compressor as a low pressure spool in said first direction about said central axis;

a power density that is greater than or equal to about 1.5 and less than or equal to about 5.5 lbf/in 3 , said power density is calculated using a value that is sea level take-off, flat-rated static thrust;

a fan connected to the low pressure spool via a speed changing mechanism and will rotate in a second direction opposed to said first direction; and

guide vanes positioned upstream of a first stage in said low pressure turbine to direct gases downstream of said high pressure turbine as they approach said low pressure turbine, wherein said guide vanes are highly cambered such that said vanes direct products of combustion downstream of the high pressure turbine to be properly directed when initially encountering the first stage of the low pressure turbine.

10 . The engine as set forth in claim 1 , wherein said fan section delivering a portion of air into a bypass duct and a portion of the air into said low pressure compressor as core flow, and having a bypass ratio greater than 6.

11 . A gas turbine engine turbine comprising:

a high pressure turbine configured to rotate with a high pressure compressor as a pressure spool in a first direction about a central axis;

a low pressure turbine configured to rotate with a low pressure compressor as a low pressure spool in said first direction about said central axis;

a power density that is greater than or equal to about 1.5 and less than or equal to about 5.5 lbf/in 3 ; and

a fan connected to the low pressure spool via a speed changing mechanism and will rotate in a second direction opposed to said first direction, said fan section delivering a portion of air into a bypass duct and a portion of the air into said low pressure compressor as core flow, and having a bypass ratio greater than 6, and wherein said speed changing mechanism is a gear reduction.

12 . The engine as set forth in claim 11 , wherein a star gear is utilized to change the direction of rotation between said fan and said low pressure spool.

13 . The engine as set forth in claim 12 , wherein said star gear arrangement having a gear ratio above 2.3:1, meaning that the low pressure spool turns at least or equal to about 2.3 times as fast as said fan.

14 . The engine as set forth in claim 1 , wherein said speed changing mechanism is a gear reduction.

15 . The engine as set forth in claim 14 , wherein a star gear is utilized to change the direction of rotation between said fan and said low pressure spool.

16 . The engine as set forth in claim 15 , wherein said star gear arrangement having a gear ratio above 2.3:1, meaning that the low pressure spool turns at least or equal to about 2.3 times as fast as said fan.

17 . A gas turbine engine turbine comprising:

a high pressure turbine configured to rotate with a high pressure compressor as a high pressure spool in a first direction about a central axis;

a low pressure turbine configured to rotate with a low pressure compressor as a low pressure spool in said first direction about said central axis;

a power density that is greater than or equal to about 4.0; and

a fan connected to the low pressure spool via a speed changing mechanism and will rotate in a second direction opposed to said first direction.

18 . The engine as set forth in claim 17 , wherein said power density is a ratio of a thrust provided by said engine to a volume of a turbine section including both said high pressure turbine and said low pressure turbine, said thrust is sea level take-off, flat-rated static thrust.

19 . The engine as set forth in claim 17 , wherein said fan section delivering a portion of air into a bypass duct and a portion of the air into said low pressure compressor as core flow, and having a bypass ratio greater than 6.

20 . The engine as set forth in claim 17 , wherein a star gear is utilized to change the direction of rotation between said fan and said low pressure spool.