# US 10,502,139 B2 · Method of starting a gas turbine engine including a cooling phase > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,502,139 B2 - Document ID: US10502139B2 - Status: Granted - Kind: B2 - Application number: 14/607,401 - Filed: 2015-01-28 - Published: 2016-12-01 - Granted: 2019-12-10 - Earliest claimed: 2015-01-28 - Assignees: General Electric Company - Applicants: General Electric Company - Inventors: Steven Alan Ross; Mark Edward Linz; Joseph Daniel Garrett, III; Amid Ansari; Joseph Roger Broda; Thomas Earl Gillingham; Kevin Richard Graziano; Robert Charles Hon; Kenneth Kirchmayer; Daniel Roy Kiracofe; Andrew Todd Lehmann; Michael Scott McCambridge; Tod Robert Steen; Thomas Charles Swager - Web page: https://patentgrep.com/patent/US10502139B2 ## CPC - F02C 7/26: Starting; Ignition - F01D 19/02: dependent on temperature of component parts, e.g. of turbine-casing - F02C 3/04: having a turbine driving a compressor (power transmission arrangements F02C7/36; control of working fluid flow F02C9/16) - F02C 7/12: Cooling of plants (of component parts, see the relevant subclasses, e.g. F01D; cooling of engines in general F01P) - F02C 7/268: Starting drives for the rotor {, acting directly on the rotor of the gas turbine to be started} - F02C 9/00: Controlling gas-turbine plants; Controlling fuel supply in air- breathing jet-propulsion plants (controlling air intakes F02C7/057; controlling turbines F01D; controlling compressors F04D27/00; controlling in general G05) - F05D 2260/85: Starting - F05D 2270/042: by keeping it below damagingly high values - F05D 2270/304: Spool rotational speed - Y02T 50/60: Efficient propulsion technologies, e.g. for aircraft - 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 ## Abstract A method of starting a gas turbine engine having a rotor comprising at least a shaft-mounted compressor and turbine, with a casing surrounding the rotor includes an acceleration phase, a bowed-rotor cooling phase, during the acceleration, and a combustion phase. The bowed-rotor cooling phase comprises a time where the rotational speed of the rotor is maintained below a bowed-rotor threshold speed until a non-bowed condition is satisfied, wherein the air forced through the gas turbine engine cools the rotor. The combustion phase occurs after the bowed-rotor cooling phase and upon reaching the combustion speed, wherein fuel is supplied to the gas turbine engine. ## Claims ### Claim 1 A method of starting a gas turbine engine having a rotor comprising at least a shaft mounted compressor and turbine, with a casing surrounding the rotor, the method comprising: initiating a first acceleration phase where the rotational speed of the rotor is increased toward a combustion speed to force air through the gas turbine engine; sensing vibrations during the first acceleration phase while the rotational speed of the rotor is equal to or less than 500 rpm; sensing a first bowed rotor condition during the first acceleration phase; initiating a first bowed-rotor cooling phase during the first acceleration phase, where the rotational speed of the rotor is maintained below a first bowed-rotor threshold speed until a first non-bowed rotor condition is satisfied, wherein the air forced through the gas turbine engine cools the rotor; sensing the first non-bowed rotor condition; thereafter, initiating a second acceleration phase, wherein the rotor speed is increased from at least 500 rpm toward the combustion speed; sensing a second bowed rotor condition during the second acceleration phase; initiating a second bowed-rotor cooling phase during the second acceleration phase, where the rotational speed of the rotor is decelerated below a second bowed-rotor threshold speed and above the first bowed-rotor threshold speed until a second non-bowed rotor condition is satisfied, wherein the air forced through the gas turbine engine cools the rotor; sensing the second non-bowed rotor condition; and thereafter, initiating a combustion phase, where upon reaching the combustion speed during the combustion phase fuel is supplied to the gas turbine engine and ignition is turned on. ### Claim 2 (depends on 1) The method of claim 1, wherein the rotor is accelerated during the first bowed rotor cooling phase at an acceleration rate that is slower than during the first acceleration phase prior to sensing the first bowed rotor condition. ### Claim 3 (depends on 1) The method of claim 1, wherein the rotor is accelerated during the second bowed rotor cooling phase at an acceleration rate that is slower than during the second acceleration phase prior to sensing the second bowed rotor condition. ### Claim 4 (depends on 1) The method of claim 1, wherein the first acceleration phase and the second acceleration phase comprise externally rotating the rotor. ### Claim 5 (depends on 1) The method of claim 1, wherein the first bowed-rotor threshold speed comprises a non-contact speed below which the rotor does not contact the casing. ### Claim 6 (depends on 5) The method of claim 5, wherein the non-contact speed is less than a natural frequency of the turbine engine. ### Claim 7 (depends on 1) The method of claim 1, wherein the first non-bowed-rotor condition comprises a rotational imbalance of the rotor. ### Claim 8 (depends on 1) The method of claim 1, wherein sensing the first non-bowed rotor condition comprises: sensing a rotational imbalance of the rotor during the first bowed-rotor cooling phase; and determining that the rotational imbalance is less than a rotational imbalance threshold to satisfy the first non-bowed-rotor condition. ### Claim 9 (depends on 1) The method of claim 1, wherein sensing the first non-bowed rotor condition comprises: monitoring a temperature at multiple portions of the rotor; and determining when the temperatures monitored are within a predetermined range of each other to satisfy the first non-bowed rotor condition. ### Claim 10 (depends on 1) The method of claim 1, wherein the second non-bowed-rotor condition comprises a rotational imbalance of the rotor. ### Claim 11 (depends on 1) The method of claim 1, wherein sensing the second non-bowed rotor condition comprises: sensing the rotational imbalance of the rotor during the second bowed-rotor cooling phase; and determining that the rotational imbalance is less than a rotational imbalance threshold to satisfy the second non-bowed-rotor condition. ### Claim 12 (depends on 1) The method of claim 1, wherein sensing the second non-bowed rotor condition comprises: monitoring a temperature at multiple portions of the rotor; and determining when the temperatures monitored are within a predetermined range of each other to satisfy the second non-bowed rotor condition. ### Claim 13 (depends on 1) The method of claim 1, wherein maintaining the rotational speed of the rotor below the first bowed-rotor threshold speed comprises maintaining the rotational speed of the rotor at a substantially constant speed. ### Claim 14 (depends on 13) The method of claim 13, wherein the constant speed is less than a natural frequency of the turbine engine. ### Claim 15 A method of starting a gas turbine engine having a rotor comprising at least a shaft mounted compressor and turbine, with a casing surrounding the rotor, the method comprising: accelerating the rotor during an acceleration phase, where the rotational speed of the rotor is increased toward a combustion speed to force air through the gas turbine engine; actively sensing vibrations during a condition monitoring phase during the acceleration phase, wherein vibrations are actively monitored while the rotational speed of the rotor is equal to or less than 500 rpm; actively sensing vibrations during a bowed-rotor condition monitoring phase in the acceleration phase, where the rotor is monitored for a bowed-rotor condition; maintaining a first rotational speed of the rotor, during a first bowed-rotor cooling phase during the acceleration phase, below a non-contact speed below which the rotor does not contact the casing upon the presence of the bowed-rotor condition; and maintaining a second rotational speed of the rotor during a second bowed-rotor cooling phase following the first bowed-rotor cooling phase, whereupon in the presence of the bowed-rotor condition the rotational speed of the rotor continues to be maintained below the non-contact speed below which the rotor does not contact the casing, and wherein the second rotational speed of the rotor is greater than the first rotational speed, wherein at least a portion of the bowed-rotor condition monitoring phase occurs after initiating the first bowed-rotor cooling phase.