# US 9,752,511 B2 · Geared architecture for high speed and small volume fan drive turbine > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,752,511 B2 - Document ID: US9752511B2 - Status: Granted - Kind: B2 - Application number: 15/484,441 - Filed: 2017-04-11 - Published: 2017-08-03 - Granted: 2017-09-05 - Earliest claimed: 2011-06-08 - Assignees: United Technologies Corporation - Applicants: United Technologies Corporation - Inventors: Michael E. McCune; Jason Husband; Frederick M. Schwarz; Daniel Bernard Kupratis; Gabriel L. Suciu; William K. Ackermann - Web page: https://patentgrep.com/patent/US9752511B2 ## CPC - F02K 3/06: with front fan - F02C 3/107: with two or more rotors connected by power transmission - F02C 7/36: Power transmission arrangements between the different shafts of the gas turbine plant, or between the gas-turbine plant and the power user ({F02C3/107 - F02C3/13 and} F02C7/32 take precedence; couplings for transmitting rotation F16D; gearing in general F16H) - F01D 5/06: Rotors for more than one axial stage, e.g. of drum or multiple disc type; Details thereof, e.g. shafts, shaft connections {(F01D5/022, F01D5/023 take precedence)} - F01D 9/041: {using blades (F01D5/148 takes precedence)} - F01D 15/12: Combinations with mechanical gearing (driven by multiple engines F01D13/00) - F02C 7/20: Mounting or supporting of plant; Accommodating heat expansion or creep - F04D 19/002: {Axial flow fans} - F04D 25/045: {the pump wheel carrying the fluid driving means, e.g. turbine blades} - F04D 29/053: Shafts - F04D 29/325: {for axial flow fans (blade mountings F04D29/34, blades F04D29/38)} - F05D 2220/32: in gas turbines - F05D 2220/323: for aircraft propulsion, e.g. jet engines - F05D 2240/60: Shafts - F05D 2260/4031: as in toothed gearing - F05D 2260/40311: of the epicyclical, planetary or differential type - F05D 2300/501: Elasticity - Y02T 50/60: Efficient propulsion technologies, e.g. for aircraft - F02K: JET-PROPULSION PLANTS (features of jet-propulsion plants common to gas-turbine plants, air intakes or fuel supply control of air-breathing jet-propulsion plants F02C7/00, F02C9/00) - F02C: GAS-TURBINE PLANTS; AIR INTAKES FOR JET-PROPULSION PLANTS; CONTROLLING FUEL SUPPLY IN AIR-BREATHING JET-PROPULSION PLANTS (construction of turbines F01D; jet-propulsion plants F02K; construction of compressors or fans F04; generating combustion products of high pressure or high velocity F23R; using gas turbines in compression refrigeration plants F25B11/00) - F01D: NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES (machines or engines for liquids F03; non-positive displacement pumps F04D) - F04D: NON-POSITIVE-DISPLACEMENT PUMPS (engine fuel-injection pumps F02M; ion pumps H01J41/12; electrodynamic pumps H02K44/02) - F05D: INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS - Y02T: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION ## 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. ## Claims ### Claim 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, 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. ### Claim 2 (depends on 1) The gas turbine engine as set forth in claim 1, wherein a mid-turbine frame is positioned between said first and second turbine sections, and includes a plurality of airfoils positioned in a flow path. ### Claim 3 (depends on 2) The gas turbine engine as set forth in claim 2, wherein said first turbine section includes a first turbine having an inlet, an outlet, and a first turbine pressure ratio greater than 5, wherein said first turbine pressure ratio is a ratio of a pressure measured prior to said inlet as related to a pressure at said outlet and prior to any exhaust nozzle. ### Claim 4 (depends on 3) The gas turbine engine as set forth in claim 3, including a power ratio of a flat-rated Sea Level Take-Off thrust provided by said engine in lbf, to a volume of a turbine section including both said first and second turbine sections in inch3 being greater than or equal to 4.0 lbf/inch3. ### Claim 5 (depends on 4) The gas turbine engine as set forth in claim 4, wherein said flexible support lateral stiffness and said flexible support transverse stiffness both are less than 11% of a respective one of said frame lateral stiffness and said frame transverse stiffness. ### Claim 6 (depends on 5) The gas turbine engine as set forth in claim 5, wherein said fan section has a low corrected fan tip speed less than 1,150 ft/sec, wherein said low corrected fan tip speed is an actual fan tip speed divided by [(Tram ° R)/(518.7° R)]0.5. ### Claim 7 (depends on 6) The gas turbine engine as set forth in claim 6, wherein said performance quantity ratio is less than or equal to 1.075. ### Claim 8 (depends on 3) The gas turbine engine as set forth in claim 3, including said power ratio being greater than or equal to 1.5 lbf/inch3. ### Claim 9 (depends on 8) The gas turbine engine as set forth in claim 8, wherein said fan section has a low corrected fan tip speed less than 1,150 ft/sec, wherein said low corrected fan tip speed is an actual fan tip speed divided by [(Tram ° R)/(518.7° R)]0.5. ### Claim 10 (depends on 3) The gas turbine engine as set forth in claim 3, wherein said power ratio being greater than or equal to 4.0 and less than or equal to 5.5 lbf/inch3. ### Claim 11 (depends on 1) The gas turbine engine as set forth in claim 1, wherein said fan section has a low corrected fan tip speed less than 1,150 ft/sec, wherein said low corrected fan tip speed is an actual fan tip speed divided by [(Tram ° R)/(518.7° R)]0.5. ### Claim 12 (depends on 11) The gas turbine engine as set forth in claim 11, wherein said performance quantity ratio is less than or equal to 1.075. ### Claim 13 (depends on 1) The gas turbine engine as set forth in claim 1, wherein said performance quantity ratio is greater than or equal to 0.8. ### Claim 14 (depends on 13) The gas turbine engine as set forth in claim 13, wherein said flexible support lateral stiffness and said flexible support transverse stiffness both are less than 11% of a respective one of said frame lateral stiffness and said frame transverse stiffness. ### Claim 15 (depends on 14) The gas turbine engine as set forth in claim 14, wherein said plurality of gears have a gear mesh transverse stiffness, and said flexible support transverse stiffness is less than 8% of said gear mesh transverse stiffness. ### Claim 16 A gas turbine engine comprising: 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. ### Claim 17 (depends on 16) The gas turbine engine as set forth in claim 16, including a power ratio of a flat-rated Sea Level Take-Off thrust provided by said engine in lbf, to a volume of a turbine section including both said first and second turbine sections in inch3 being greater than or equal to 1.5 and less than or equal to 5.5 lbf/inch3. ### Claim 18 (depends on 16) The gas turbine engine as set forth in claim 16, wherein both said flexible support lateral stiffness and said flexible support transverse stiffness are less than 11% of a respective one of said frame lateral stiffness and said frame transverse stiffness. ### Claim 19 (depends on 18) The gas turbine engine set forth in claim 18, wherein a fan section including said fan is configured to include a low fan pressure ratio of less than 1.45, said low fan pressure ratio measured across said fan blades alone. ### Claim 20 (depends on 19) The gas turbine engine as set forth in claim 19, wherein said plurality of gears is an epicyclic gear system having a gear reduction ratio of greater than 2.3. ### Claim 21 (depends on 20) The gas turbine engine as set forth in claim 20, wherein said performance quantity being greater than or equal to 0.8 and said second speed is more than twice said first speed. ### Claim 22 (depends on 20) The gas turbine engine as set forth in claim 20, wherein said plurality of gears have a gear mesh transverse stiffness, and said flexible support transverse stiffness is less than 8% of said gear mesh transverse stiffness. ### Claim 23 (depends on 17) The gas turbine engine as set forth in claim 17, wherein said power ratio being greater than or equal to 4.0 lbf/inch3. ### Claim 24 (depends on 23) The gas turbine engine as set forth in claim 23, wherein said plurality of gears is an epicyclic gear system having a gear reduction ratio greater than 2.3, 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. ### Claim 25 (depends on 24) The gas turbine engine as set forth in claim 24, wherein both said flexible support lateral stiffness and said flexible support transverse stiffness are less than 11% of a respective one of said frame lateral stiffness and said frame transverse stiffness. ### Claim 26 (depends on 25) The gas turbine engine as set forth in claim 25, wherein said fan section has a low corrected fan tip speed less than 1,150 ft/sec, wherein said low corrected fan tip speed is an actual fan tip speed divided by [(Tram ° R)/(518.7° R)]0.5. ### Claim 27 (depends on 16) The gas turbine engine as set forth in claim 16, wherein both said flexible support lateral stiffness and said flexible support transverse stiffness are less than 11% of a respective one of said frame lateral stiffness and said frame transverse stiffness. ### Claim 28 (depends on 27) The gas turbine engine as set forth in claim 27, wherein said performance quantity ratio is greater than or equal to 0.8, said plurality of gears is an epicyclic gear system having a gear reduction ratio greater than 2.3. ### Claim 29 (depends on 16) The gas turbine engine as set forth in claim 16, wherein said performance quantity ratio is greater than or equal to 0.8, and said plurality of gears is an epicyclic gear system having a gear reduction ratio greater than 2.3. ### Claim 30 (depends on 29) The gas turbine engine as set forth in claim 29, wherein said epicyclic gear system has a gear mesh transverse stiffness, and said flexible support transverse stiffness is less than 8% of said gear mesh transverse stiffness.