# US 11,027,827 B2 · Method for separated flow detection > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,027,827 B2 - Document ID: US11027827B2 - Status: Granted - Kind: B2 - Application number: 16/121,517 - Filed: 2018-09-04 - Published: 2020-03-05 - Granted: 2021-06-08 - Earliest claimed: 2018-09-04 - Assignees: Raytheon Technologies Corporation - Applicants: United Technologies Corporation - Inventors: Dmitriy B. Sidelkovskiy - Web page: https://patentgrep.com/patent/US11027827B2 ## CPC - F02C 7/04: Air intakes for gas-turbine plants or jet-propulsion plants - B64C 21/00: Influencing air flow over aircraft surfaces by affecting boundary layer flow - B64D 29/00: Power-plant nacelles, fairings or cowlings - B64D 33/02: of combustion air intakes - F01D 17/08: responsive to condition of working-fluid, e.g. pressure - F02C 7/057: Control or regulation (conjointly with fuel supply control F02C9/50, with nozzle area control F02K1/16) - B64C 2230/04: by actively generating fluid flow - F05D 2220/323: for aircraft propulsion, e.g. jet engines - F05D 2260/80: Diagnostics - F05D 2270/102: caused by working fluid flow velocity profile distortion - F05D 2270/3011: Inlet pressure - F05D 2270/80: Devices generating input signals, e.g. transducers, sensors, cameras or strain gauges - 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) - B64C: AEROPLANES; HELICOPTERS - B64D: EQUIPMENT FOR FITTING IN OR TO AIRCRAFT; FLIGHT SUITS; PARACHUTES; ARRANGEMENT OR MOUNTING OF POWER PLANTS OR PROPULSION TRANSMISSIONS IN AIRCRAFT - 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 A method to predict an onset of flow separation from a surface of an inner barrel of a nacelle is disclosed. In various embodiments, the method includes determining a static pressure distribution about the inner barrel surface of the nacelle; determining a mean static pressure value and a minimum static pressure value using the static pressure distribution; determining a separation indicator value using the mean static pressure value and the minimum static pressure value; and comparing the separation indicator value against a separation threshold value. ## Claims ### Claim 1 A method to predict an onset of flow separation from a surface of an inner barrel of a nacelle, comprising: determining a static pressure distribution about the inner barrel surface of the nacelle; determining a mean static pressure value and a minimum static pressure value using the static pressure distribution; determining a separation indicator value using the mean static pressure value and the minimum static pressure value; and comparing the separation indicator value against a separation threshold value. ### Claim 2 (depends on 1) The method of claim 1, wherein determining the static pressure distribution about the surface of the inner barrel includes receiving by a controller a discrete set of static pressure values taken from the surface of the inner barrel. ### Claim 3 (depends on 2) The method of claim 2, wherein the discrete set of static pressure values is taken from a reference plane positioned circumferentially about the surface of the inner barrel. ### Claim 4 (depends on 2) The method of claim 2, wherein determining the mean static pressure value comprises calculating by the controller an arithmetic mean of the discrete set of static pressure values. ### Claim 5 (depends on 4) The method of claim 4, wherein determining the minimum static pressure value comprises calculating by the controller an arithmetic minimum of the discrete set of static pressure values. ### Claim 6 (depends on 5) The method of claim 5, wherein determining the separation indicator value using the mean static pressure value and the minimum static pressure value comprises calculating by the controller an arithmetic difference by subtracting the mean static pressure value from the minimum static pressure value. ### Claim 7 (depends on 6) The method of claim 6, wherein determining the separation indicator value using the mean static pressure value and the minimum static pressure value further comprises normalizing the separation indicator value by a total pressure value to obtain a normalized-separation indicator value. ### Claim 8 (depends on 7) The method of claim 7, wherein the separation threshold value is within a range equal from about negative ten one-hundredths to about negative twelve one-hundredths. ### Claim 9 (depends on 8) The method of claim 8, wherein comparing the separation indicator value against the separation threshold value comprises determining by the controller whether the normalized-separation indicator value is less than or greater than the separation threshold value. ### Claim 10 (depends on 1) The method of claim 1, wherein comparing the separation indicator value against the separation threshold value comprises comparing the separation indicator value against a first separation threshold value to predict the onset of flow separation and comparing the separation indicator value against a second separation threshold value to predict an occurrence of flow separation. ### Claim 11 A system to predict an onset of flow separation from a surface of an inner barrel of a nacelle, comprising: a plurality of static pressure sensors distributed about the surface of the inner barrel; and a controller configured to: calculate a static pressure distribution about the inner barrel surface of the nacelle using data provided to the controller from the plurality of static pressure sensors; calculate a mean static pressure value and a minimum static pressure value using the static pressure distribution; calculate a separation indicator value using the mean static pressure value and the minimum static pressure value; and compare the separation indicator value against a separation threshold value. ### Claim 12 (depends on 11) The system of claim 11, wherein the plurality of static pressure sensors is positioned circumferentially about a reference plane and configured to provide a discrete set of static pressure values. ### Claim 13 (depends on 12) The system of claim 12, wherein the mean static pressure value is determined by the controller by calculating an arithmetic mean of the discrete set of static pressure values. ### Claim 14 (depends on 13) The system of claim 13, wherein the minimum static pressure value is determined by the controller by calculating an arithmetic minimum of the discrete set of static pressure values. ### Claim 15 (depends on 14) The system of claim 14, wherein the separation indicator value is determined by the controller by subtracting the mean static pressure value from the minimum static pressure value. ### Claim 16 (depends on 15) The system of claim 15, further comprising a total pressure sensor configured to provide a total pressure value to the controller and wherein the controller is configured to determine a normalized-separation indicator value by normalizing the separation indicator value by the total pressure value. ### Claim 17 (depends on 16) The system of claim 16, wherein the separation threshold value is within a range equal from about negative ten one-hundredths to about negative twelve one-hundredths. ### Claim 18 (depends on 17) The system of claim 17, wherein the controller is configured to calculate whether the normalized-separation indicator value is less than or greater than the separation threshold value. ### Claim 19 A gas turbine engine, comprising: a nacelle having an inner barrel surface; a plurality of static pressure sensors spaced circumferentially about the inner barrel surface; a controller configured to: calculate a static pressure distribution about the inner barrel surface of the nacelle using data provided to the controller from the plurality of static pressure sensors; calculate a mean static pressure value and a minimum static pressure value using the static pressure distribution; calculate a separation indicator value using the mean static pressure value and the minimum static pressure value; and compare the separation indicator value against a separation threshold value. ### Claim 20 (depends on 19) The gas turbine engine of claim 19, wherein the controller is configured to calculate the separation indicator value is by subtracting the mean static pressure value from the minimum static pressure value and wherein the controller is configured to calculate a normalized-separation indicator value by normalizing the separation indicator value by a total pressure value.