Geared architecture for high speed and small volume fan drive turbine
First Claim
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1. A gas turbine engine comprising:
- a fan shaft driving a fan having fan blades;
a frame which supports said fan shaft, said frame having a frame lateral stiffness and a frame transverse stiffness;
an epicyclic gear system having a gear reduction ratio of greater than 2.3;
a flexible support which supports said epicyclic gear system and has a flexible support lateral stiffness and a flexible support transverse stiffness, and at least one of said flexible support lateral stiffness and said flexible support transverse stiffness is less than 11% of a respective one of said frame lateral stiffness and said frame transverse stiffness;
a first turbine section providing a drive input into a sun gear in an epicyclic gear system;
a second turbine section, andwherein said first turbine section has a first exit area at a first exit point and rotates at a first speed,wherein said second turbine section has a second exit area at a second exit point and rotates at a second speed, which is faster than said first speed, said first and second speeds being redline speeds,wherein a first performance quantity is defined as the product of said first speed squared and said first area,wherein a second performance quantity is defined as the product of said second speed squared and said second area,wherein a performance quantity ratio of said first performance quantity to said second performance quantity is between 0.5 and 1.5; and
a fan section including said fan is configured to include a low fan pressure ratio of less than 1.45 measured across said fan blades alone.
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Abstract
A gas turbine engine includes a gear system that provides a speed reduction between a fan drive turbine and a fan rotor. Aspects of the gear system are provided with some flexibility. The fan drive turbine has a first exit area and rotates at a first speed. A second turbine section has a second exit area and rotates at a second speed, which is faster than said first speed. A performance quantity can be defined for both turbine sections as the products of the respective areas and respective speeds squared. A performance quantity ratio of the performance quantity for the fan drive turbine to the performance quantity for the second turbine section is relatively high.
239 Citations
30 Claims
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1. A gas turbine engine comprising:
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a fan shaft driving a fan having fan blades; a frame which supports said fan shaft, said frame having a frame lateral stiffness and a frame transverse stiffness; an epicyclic gear system having a gear reduction ratio of greater than 2.3; a flexible support which supports said epicyclic gear system and has a flexible support lateral stiffness and a flexible support transverse stiffness, and at least one of said flexible support lateral stiffness and said flexible support transverse stiffness is less than 11% of a respective one of said frame lateral stiffness and said frame transverse stiffness; a first turbine section providing a drive input into a sun gear in an epicyclic gear system; a second turbine section, and wherein said first turbine section has a first exit area at a first exit point and rotates at a first speed, wherein said second turbine section has a second exit area at a second exit point and rotates at a second speed, which is faster than said first speed, said first and second speeds being redline speeds, wherein a first performance quantity is defined as the product of said first speed squared and said first area, wherein a second performance quantity is defined as the product of said second speed squared and said second area, wherein a performance quantity ratio of said first performance quantity to said second performance quantity is between 0.5 and 1.5; and a fan section including said fan is configured to include a low fan pressure ratio of less than 1.45 measured across said fan blades alone. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. A gas turbine engine comprising:
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a fan shaft driving a fan having fan blades and a frame supporting said fan shaft and having a frame lateral stiffness and a frame transverse stiffness; a plurality of gears which drive said fan shaft; a flexible support which supports said plurality of gears, and has a flexible support lateral stiffness and a flexible support transverse stiffness and at least one of said flexible support lateral stiffness and said flexible support transverse stiffness is less than 11% of a respective one of said frame lateral stiffness and said frame transverse stiffness; a first turbine section providing a drive input into said plurality of gears; a second turbine section, wherein said first turbine section has a first exit area at a first exit point and rotates at a first speed, wherein said second turbine section has a second exit area at a second exit point and rotates at a second speed, which is faster than said first speed, said first and second speeds being redline speeds, wherein a first performance quantity is defined as the product of said first speed squared and said first area, wherein a second performance quantity is defined as the product of said second speed squared and said second area, wherein a performance quantity ratio of said first performance quantity to said second performance quantity is between 0.5 and 1.5; and a bypass ratio greater than 10. - View Dependent Claims (17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30)
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Specification