# US 2014/0196470 A1 · Gas turbine engine buffer system > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2014/0196470 A1 - Document ID: US20140196470A1 - Status: Published application - Kind: A1 - Application number: 14/219,070 - Filed: 2014-03-19 - Published: 2014-07-17 - Earliest claimed: 2012-01-31 - Assignees: United Technologies Corporation - Applicants: United Technologies Corporation - Inventors: Jorn A. Glahn; Clifton J. Crawley, JR.; Philip S. Stripinis; William K. Ackermann - Web page: https://patentgrep.com/patent/US20140196470A1 ## CPC - F02C 9/18: by bleeding, bypassing or acting on variable working fluid interconnections between turbines or compressors or their stages {(F02C3/113 takes precedence)} - F01D 11/04: using sealing fluid, e.g. steam - F01D 25/00: Component parts, details, or accessories, not provided for in, or of interest apart from, other groups - F01D 25/16: Arrangement of bearings; Supporting or mounting bearings in casings (bearings per se F16C) - F02C 6/08: the gas being bled from the gas-turbine compressor - F02C 7/06: Arrangements of bearings (bearings F16C); Lubricating ({of turbo machines F01D25/18; of machines or} engines in general F01M) - F02C 7/12: Cooling of plants (of component parts, see the relevant subclasses, e.g. F01D; cooling of engines in general F01P) - F02C 7/18: the medium being gaseous, e.g. air {(F02C7/125 takes precedence)} - F02C 7/28: Arrangement of seals - F05D 2260/601: using an ejector or a jet pump - Y02T 50/60: Efficient propulsion technologies, e.g. for aircraft - Y10T 29/49229: Prime mover or fluid pump making - 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) - 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 - Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION ## Abstract A gas turbine engine includes a compressor section, a combustor in fluid communication with the compressor section, a turbine section in fluid communication with the combustor, a fan section configured to be driven by the turbine section via a geared architecture, and a buffer system that communicates buffer air to a portion of the gas turbine engine. The buffer system includes a first circuit configured to selectively mix a first bleed air supply having a first pressure and a second bleed air supply having a second pressure that is greater than the first pressure to provide a first buffer supply air having an intermediate pressure compared to the first pressure and the second pressure. ## Claims ### Claim 1 A gas turbine engine, comprising: a compressor section; a combustor in fluid communication with said compressor section; a turbine section in fluid communication with said combustor; a fan section configured to be driven by the turbine section via a geared architecture; and a buffer system that communicates buffer air to a portion of the gas turbine engine, wherein the buffer system includes a first circuit configured to selectively mix a first bleed air supply having a first pressure and a second bleed air supply having a second pressure that is greater than the first pressure to provide a first buffer supply air having an intermediate pressure compared to the first pressure and the second pressure. ### Claim 2 (depends on 1) The gas turbine engine as recited in claim 1, wherein the buffer system includes a second circuit that selects between a third bleed air supply and a fourth bleed air supply to communicate a second buffer air supply to a different portion of the gas turbine engine. ### Claim 3 (depends on 2) The gas turbine engine as recited in claim 2, wherein one of said first circuit and said second circuit includes a conditioning device. ### Claim 4 (depends on 2) The gas turbine engine as recited in claim 2, wherein at least one of said first circuit and said second circuit includes at least one of an ejector and a valve. ### Claim 5 (depends on 2) The gas turbine engine as recited in claim 2, wherein the gas turbine engine is a high bypass geared aircraft engine having a bypass ratio of greater than about six (6). ### Claim 6 (depends on 5) The gas turbine engine as recited in claim 5, wherein the bypass ratio is greater than about ten (10). ### Claim 7 (depends on 6) The gas turbine engine as recited in claim 6, wherein the gas turbine engine includes a Fan Pressure Ratio of less than about 1.45. ### Claim 8 (depends on 7) The gas turbine engine as recited in claim 7, wherein the turbine section includes a fan drive turbine configured to drive the fan section through the geared architecture and the fan drive turbine section is configured to rotate at a first speed and the fan section is configured to rotate at a second speed less than the first speed. ### Claim 9 (depends on 8) The gas turbine engine as recited in claim 8, wherein the fan drive turbine has a pressure ratio that is greater than about five (5). ### Claim 10 (depends on 9) The gas turbine engine as recited in claim 9, wherein fan drive turbine is arranged on a first spool supported for rotation about an engine axis by at least one bearing structure arranged in a bearing compartment. ### Claim 11 (depends on 10) The gas turbine engine as recited in claim 10, wherein at least one of the first and second circuits supplies buffer supply air to the at least one bearing compartment. ### Claim 12 (depends on 11) The gas turbine engine as recited in claim 11, wherein the at least one bearing compartment is in the turbine section. ### Claim 13 (depends on 11) The gas turbine engine as recited in claim 11, wherein the at least one bearing compartment comprises a first bearing compartment aft of the geared architecture and a second bearing compartment forward of the geared architecture. ### Claim 14 (depends on 10) The gas turbine engine as recited in claim 10, wherein the geared architecture includes an epicyclic gear train. ### Claim 15 (depends on 14) The gas turbine engine as recited in claim 14, wherein the epicyclic gear train is a planetary gear system. ### Claim 16 (depends on 14) The gas turbine engine as recited in claim 14, wherein the epicyclic gear train has a gear reduction ratio of greater than about 2.3. ### Claim 17 (depends on 16) The gas turbine engine as recited in claim 16, wherein the epicyclic gear train has a gear reduction ratio of greater than about 2.5. ### Claim 18 (depends on 14) The gas turbine engine as recited in claim 14, wherein the compressor section comprises a first compressor and a second compressor and the turbine section comprises the fan drive turbine and a second turbine, wherein the second compressor and the second turbine are arranged on a second spool, the second spool including at least one bearing system arranged in a bearing compartment, and at least one of the first and second circuits supplies buffer supply air to the at least one bearing compartment. ### Claim 19 (depends on 18) The engine as recited in claim 18, wherein the turbine section includes the fan drive turbine, the second turbine and a third turbine, wherein the second turbine and the third turbine are configured to drive the first compressor and the second compressor. ### Claim 20 (depends on 18) The gas turbine engine as recited in claim 18, wherein the second spool rotates faster than the first spool. ### Claim 21 A method of designing a gas turbine engine comprising: defining a compressor section; defining a combustor in fluid communication with the compressor section; defining a turbine section in fluid communication with said combustor; defining a fan section configured to be driven by a turbine section via a geared architecture; and configuring a buffer system for communicating buffer air to a portion of the gas turbine engine, wherein the buffer system is defined to include a first circuit for selectively mixing a first bleed air supply having a first pressure and a second bleed air supply having a second pressure that is greater than the first pressure to provide a first buffer supply air having an intermediate pressure compared to the first pressure and the second pressure. ### Claim 22 (depends on 21) The method of designing as recited in claim 21, including defining the buffer system to include a second circuit that selects between a third bleed air supply and a fourth bleed air supply for communicating a second buffer air supply to a different portion of the gas turbine engine. ### Claim 23 (depends on 22) The method as recited in claim 22, including defining one of said first circuit and said second circuit to include a conditioning device. ### Claim 24 (depends on 23) The method as recited in claim 23, including configuring at least one of said first circuit and said second circuit to include at least one of an ejector and a valve. ### Claim 25 (depends on 24) The method as recited in claim 24, including defining the turbine section to include a fan drive turbine configured to drive the fan section through the geared architecture and configuring the fan drive turbine section to rotate at a first speed and the fan section to rotate at a second speed less than the first speed. ### Claim 26 (depends on 25) The method as recited in claim 25, including configuring the fan drive turbine to include a pressure ratio greater than about five (5). ### Claim 27 (depends on 26) The method as recited in claim 26, including configuring the fan drive turbine on a first spool supported for rotation about an engine axis by at least one bearing structure arranged in a bearing compartment. ### Claim 28 (depends on 27) The method as recited in claim 27, including configuring at least one of the first and second circuits to supply buffer supply air to the at least one bearing compartment. ### Claim 29 (depends on 28) The method as recited in claim 28, wherein the at least one bearing compartment is in the turbine section. ### Claim 30 (depends on 28) The method as recited in claim 28, wherein the at least one bearing compartment comprises a first bearing compartment aft of the geared architecture and a second bearing compartment forward of the geared architecture.