# US 11,994,089 B2 · After-fan system for a gas turbine engine > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,994,089 B2 - Document ID: US11994089B2 - Status: Granted - Kind: B2 - Application number: 16/837,143 - Filed: 2020-04-01 - Published: 2020-10-15 - Granted: 2024-05-28 - Earliest claimed: 2019-04-10 - Assignees: Rtx Corporation - Applicants: United Technologies Corporation - Inventors: Dmitriy B. Sidelkovskiy; Pitchaiah Vijay Chakka; Michael Winter; Daniel Bernard Kupratis - Web page: https://patentgrep.com/patent/US11994089B2 ## CPC - F02K 3/04: the plant including ducted fans, i.e. fans with high volume, low pressure outputs, for augmenting the jet thrust, e.g. of double-flow type - F02K 3/06: with front fan - F02C 9/20: by throttling; by adjusting vanes - F04D 29/323: {adjustable} - F01D 17/162: {for axial flow, i.e. the vanes turning around axes which are essentially perpendicular to the rotor centre line (F01D17/167 takes precedence)} - 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) - F05D 2220/323: for aircraft propulsion, e.g. jet engines - F05D 2220/36: specially adapted for the fan of turbofan engines - F05D 2240/12: Fluid guiding means, e.g. vanes - F05D 2240/35: Combustors or associated equipment - F05D 2260/40311: of the epicyclical, planetary or differential type - F05D 2260/74: by turning around an axis perpendicular the rotor centre line - F05D 2260/79: Bearing, support or actuation arrangements therefor - 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) - F04D: NON-POSITIVE-DISPLACEMENT PUMPS (engine fuel-injection pumps F02M; ion pumps H01J41/12; electrodynamic pumps H02K44/02) - 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 ## Abstract An after-fan system for a gas turbine engine includes a variable pitch fan exit guide vane array. An after-fan turbine downstream of the variable pitch fan exit guide vane array and a control operable to vary a pitch of the variable fan exit guide vane array. A method of generating thrust for a gas turbine engine includes rotating a fan section with an array of fan blades; rotating an after-fan turbine downstream of the fan section; and varying a pitch of a variable fan exit guide vane array downstream of the fan section and upstream of the after-fan turbine. ## Claims ### Claim 1 An after-fan system for a gas turbine engine, comprising: a variable pitch fan exit guide vane array; an after-fan turbine downstream of the variable pitch fan exit guide vane array, wherein the after-f an turbine is configured to extract a portion of energy from a compressed bypass flow from a fan section and return the portion of the energy to the fan section through torque; and a control operable to vary a pitch of the variable pitch fan exit guide vane array. ### Claim 2 (depends on 1) The after-fan system as recited in claim 1, wherein the variable pitch fan exit guide vane array comprises a split variable pitch fan exit guide vane array. ### Claim 3 (depends on 2) The after-fan system as recited in claim 2, wherein the split variable pitch fan exit guide vane array includes a first variable pitch fan exit guide vane array and a second variable pitch fan exit guide vane array inboard of the first variable pitch fan exit guide vane array. ### Claim 4 (depends on 3) The after-fan system as recited in claim 3, wherein the first variable pitch fan exit guide vane array and the second variable pitch fan exit guide vane array are independently adjustable in the pitch. ### Claim 5 (depends on 4) The after-fan system as recited in claim 4, wherein the first variable pitch fan exit guide vane array and the second variable pitch fan exit guide vane array are separated by a splitter. ### Claim 6 (depends on 5) The after-fan system as recited in claim 5, wherein the after-fan turbine is located within the splitter. ### Claim 7 (depends on 5) The after-fan system as recited in claim 5, wherein the after-fan turbine is located downstream of the splitter. ### Claim 8 (depends on 1) The after-fan system as recited in claim 1, wherein the variable pitch fan exit guide vane array is downstream of the fan section. ### Claim 9 (depends on 1) The after-fan system as recited in claim 1, wherein the variable pitch fan exit guide vane array is downstream of a low pressure compressor section. ### Claim 10 A gas turbine engine, comprising: a fan section with an array of fan blades; a variable pitch fan exit guide vane array downstream of the fan section; and a short span after-fan turbine downstream of the variable pitch fan exit guide vane array, said short span after-fan turbine being positioned between an outer profile of a core static structure and a ring splitter located radially inboard of an inner periphery of a fan nacelle, the short span after-fan turbine being contained radially within the ring splitter, wherein the short span after-fan turbine is configured to extract a portion of energy from a compressed bypass flow from the fan section and return the portion of the energy to the fan section through torque. ### Claim 11 (depends on 10) The gas turbine engine as recited in claim 10, wherein the variable pitch fan exit guide vane array is downstream of a low pressure compressor section which is downstream of the fan section. ### Claim 12 (depends on 10) The gas turbine engine as recited in claim 10, wherein the short span after-fan turbine is driven in concert with the fan section. ### Claim 13 (depends on 10) The gas turbine engine as recited in claim 10, wherein the short span after-fan turbine is driven by a geared architecture which also drives the fan section. ### Claim 14 (depends on 10) The gas turbine engine as recited in claim 10, wherein the gas turbine engine is a high bypass gas turbine engine. ### Claim 15 (depends on 10) The gas turbine engine as recited in claim 10, wherein the gas turbine engine is a low bypass gas turbine engine. ### Claim 16 (depends on 15) The gas turbine engine as recited in claim 15, wherein the low bypass gas turbine engine is variable cycle. ### Claim 17 A method of generating thrust fora gas turbine engine, comprising: rotating a fan section with an array of fan blades; rotating a short span after-fan turbine downstream of the fan section, said short span after-fan turbine being positioned between an outer profile of a core static structure and a ring splitter located radially inboard of an inner periphery of a fan nacelle, the short span after-fan turbine being contained radially within the ring splitter, wherein the short span after-fan turbine extracts a portion of energy from a compressed bypass flow from the fan section and return the portion of the energy to the fan section through torque; and varying a pitch of a variable pitch fan exit guide vane array downstream of the fan section and upstream of the short span after-fan turbine. ### Claim 18 (depends on 17) The method as recited in claim 17, further comprising locating the variable pitch fan exit guide vane array and the short span after-fan turbine downstream of a low pressure compressor section. ### Claim 19 (depends on 17) The method as recited in claim 17, wherein said varying the pitch of the variable pitch fan exit guide vane array comprises independently varying a pitch of an outer diameter section of the variable pitch fan exit guide vane array and an inner diameter section of the variable pitch fan exit guide vane array. ### Claim 20 (depends on 17) The method as recited in claim 17, further comprising locating the ring splitter between an outer diameter section of the variable pitch fan exit guide vane array and an inner diameter section of the variable pitch fan exit guide vane array.