Gas turbine engine with compressor inlet guide vane positioned for starting

Abstract

A gas turbine engine includes a variable inlet guide vane positioned forwardly of a low pressure compressor. The angle of the inlet guide vane is controlled at startup to increase airflow into the compressor. This is particularly useful when the gas turbine engine is being restarted while an associated aircraft is in the air, and is relied upon to increase windmill speed of the compressor and turbine rotors. A method and variable inlet vane are also disclosed.

1 . A gas turbine engine comprising:
 a compressor section;   a low spool;   a fan;   said fan delivering air into said compressor section, and said compressor section compressing air and delivering it into a combustion section;   the combustion section mixing air with fuel, igniting the fuel, and driving the products of the combustion across turbine rotors;   said compressor section including a variable inlet guide vane which is movable between distinct angles to control the airflow approaching said compressor section;   a control for said gas turbine engine, programmed to position said vane at startup of the engine to direct airflow across said compressor section; and   said fan also delivering bypass air into a bypass duct positioned outwardly of a core engine including said compressor section, said combustor, and said turbine rotors, and wherein the position of said vane is configured to direct airflow across the compressor section while an aircraft associated with the gas turbine engine is in the air, and to increase a windmilling speed of the compressor section and said turbine rotors.   
     
     
         2 . The gas turbine engine as set forth in  claim 1 , wherein said compressor section including a low pressure compressor and a high pressure compressor. 
     
     
         3 . The gas turbine engine as set forth in  claim 2 , wherein said vane is positioned forwardly of an upstream most rotor in the low pressure compressor. 
     
     
         4 . The gas turbine engine as set forth in  claim 3 , wherein said fan is driven with said low pressure compressor by said low spool, and there being a gear reduction between said fan and said low spool. 
     
     
         5 . The gas turbine engine as set forth in  claim 2 , wherein said control includes stored desired positions for said vane to provide increased airflow into the compressor at startup at various conditions. 
     
     
         6 . The gas turbine engine as set forth in  claim 5 , wherein said various conditions include the altitude of an aircraft carrying the gas turbine engine, and an air speed of the aircraft. 
     
     
         7 . The gas turbine engine as set forth in  claim 6 , wherein the conditions also include a speed of a low spool, said low spool rotating with said low pressure compressor when startup is occurring. 
     
     
         8 . The gas turbine engine as set forth in  claim 5 , wherein said bypass duct having a variable area nozzle, and the position of the nozzle also being controlled at startup to provide airflow through said bypass duct and across said fan to increase the windmilling speed. 
     
     
         9 . The gas turbine engine as set forth in  claim 8 , wherein a bypass ratio of the volume of air passing into said bypass duct to the volume delivered into said compressor section is greater than about 6. 
     
     
         10 . The gas turbine engine as set forth in  claim 1 , wherein said bypass duct having a variable area nozzle, and the position of the nozzle also being controlled at startup to provide airflow through said bypass duct and across said fan to increase the windmilling speed. 
     
     
         11 . The gas turbine engine as set forth in  claim 10 , wherein a bypass ratio of the volume of air passing into said bypass duct to the volume delivered into said compressor section is greater than about 6. 
     
     
         12 . (canceled) 
     
     
         13 . The gas turbine engine as set forth in  claim 1 , wherein a starter is also utilized in combination with the windmilling while the aircraft is in the air to start the engine. 
     
     
         14 . A method of starting a gas turbine engine comprising the steps of:
 (a) providing a variable inlet guide vane forwardly of a compressor, and moving said vane to a position at startup of the engine selected to provide airflow across said compressor;   (b) starting said gas turbine engine; and   wherein a fan delivers bypass air into a bypass duct positioned outwardly of a core engine which includes said compressor, and turbine rotors, and wherein the position of the vane is configured to direct airflow across the compressor while an aircraft associated with the gas turbine engine is in the air, and to increase a windmilling speed of the compressor and turbine rotors.   
     
     
         15 . The method as set forth in  claim 14 , wherein said desired position is selected to provide increased airflow into the compressor at startup at various conditions. 
     
     
         16 . The method as set forth in  claim 15 , wherein said various conditions include the altitude of an aircraft carrying the gas turbine engine, and the airspeed of the aircraft. 
     
     
         17 . The method as set forth in  claim 14 , wherein said compressor includes a low pressure compressor and a high pressure compressor. 
     
     
         18 . The method as set forth in  claim 16 , wherein the conditions also include a speed of a spool which drives the low pressure compressor. 
     
     
         19 . The method as set forth in  claim 18 , wherein the bypass duct having a variable area nozzle, and the position of the nozzle being controlled at startup to provide airflow across the fan to increase the windmilling speed. 
     
     
         20 . A variable inlet guide vane comprising:
 an inlet guide vane provided with an actuator to change an angle of the vane; and   a control for the actuator programmed to position said vane at a position to provide airflow across said vane at startup of an associated aircraft, and wherein the vane position is configured to direct airflow across said vane to a compressor, to increase a windmilling speed of the compressor and an associated turbine rotor while an aircraft that receives the variable inlet guide vane is in the air.   
     
     
         21 . The gas turbine engine as set forth in  claim 1 , wherein said vane is positioned at startup to maximize airflow across said compressor section. 
     
     
         22 . The method as set forth in  claim 14 , wherein said vane is positioned to maximize airflow to said compressor. 
     
     
         23 . The variable inlet guide vane as set forth in  claim 20 , wherein said vane is positioned at startup to maximize airflow to the compressor.