Gas turbine engine
A gas turbine engine is provided. The gas turbine engine includes: a fan; a turbomachine drivingly coupled to the fan and defining in part a working gas flowpath, the gas turbine engine defining a bypass passage over the turbomachine, the turbomachine defining an annular cooling passage extending between a CP inlet and a CP outlet, the CP inlet in airflow communication with the working gas flowpath and the CP outlet in airflow communication with the bypass passage; and a variable bleed assembly including a variable bleed duct extending between a VB inlet and a VB outlet, the VB inlet in airflow communication with the working gas flowpath at a location downstream of the CP inlet and the VB outlet in airflow communication with the annular cooling passage for urging an airflow through the cooling passage.
1 . A gas turbine engine comprising:
a fan assembly comprising a fan at a forward end of the gas turbine engine, the fan being a first stage of compression for the gas turbine engine;
a turbomachine drivingly coupled to the fan and comprising a compressor section, a combustion section, and a turbine section arranged in serial flow order and defining in part a working gas flowpath, the gas turbine engine defining a bypass passage over the turbomachine, the turbomachine defining an annular cooling passage extending between a CP inlet and a CP outlet, the CP inlet in airflow communication with the working gas flowpath and the CP outlet in airflow communication with the bypass passage, wherein the turbomachine defines an inlet to the working gas flowpath located downstream of the fan, wherein the compressor section defines a second stage of compression for the gas turbine engine, wherein the CP inlet is in airflow communication with the working gas flowpath at a location upstream of the second stage of compression, and wherein no intermediate stages of compression are located between the first stage of compression and the second stage of compression; and
a variable bleed assembly comprising a variable bleed duct extending between a VB inlet and both a VB outlet and supplementary VB outlet, the VB inlet in airflow communication with the working gas flowpath at a location downstream of the CP inlet, the VB outlet in airflow communication with the annular cooling passage for urging an airflow through the annular cooling passage and the supplementary VB outlet is in direct airflow communication with the bypass passage and is separated and downstream from the CP outlet.
2 . The gas turbine engine of claim 1 , wherein the compressor section comprises a compressor, and wherein the VB inlet is in airflow communication with the working gas flowpath at a location downstream of the compressor.
3 . The gas turbine engine of claim 2 , wherein the compressor is a low pressure compressor.
4 . The gas turbine engine of claim 3 , wherein the compressor section further comprises a high pressure compressor, wherein the location is upstream of the high pressure compressor.
5 . The gas turbine engine of claim 1 , wherein the variable bleed assembly comprises a variable bleed valve for varying an amount of a bleed airflow through the variable bleed duct.
6 . The gas turbine engine of claim 5 , further comprising: a controller operably coupled to the variable bleed valve, wherein the controller is configured to actuate the variable bleed assembly to increase the amount of the bleed airflow through the variable bleed duct in response to an operating condition of the gas turbine engine to increase an amount of the airflow through the annular cooling passage.
7 . The gas turbine engine of claim 1 , wherein the VB outlet forms at least in part an ejector.
8 . The gas turbine engine of claim 1 , wherein substantially all of the airflow through the variable bleed duct is provided through the VB outlet to the annular cooling passage.
9 . The gas turbine engine of claim 1 , wherein the turbomachine comprises a heat exchanger in thermal communication with the airflow through the annular cooling passage.
10 . The gas turbine engine of claim 9 , wherein the VB outlet is in airflow communication with the annular cooling passage at a location downstream of the heat exchanger.
11 . The gas turbine engine of claim 1 , wherein the fan of the fan assembly is a single stage fan.
12 . The gas turbine engine of claim 1 , wherein the fan of the fan assembly is an open rotor fan.
13 . The gas turbine engine of claim 1 , wherein the compressor section comprises a low pressure compressor and a high pressure compressor.
14 . A method of operating a gas turbine engine comprising a fan assembly and a turbomachine drivingly coupled to a fan of the fan assembly, the fan at a forward end of the gas turbine engine and being a first stage of compression for the gas turbine engine, the method comprising:
receiving data indicative of an operating condition of the gas turbine engine;
varying an amount of a variable bleed airflow through a variable bleed duct, the variable bleed duct extending between a VB inlet and both a VB outlet and a supplementary VB outlet where the VB inlet is in airflow communication with a working gas flowpath at a location downstream of a CP inlet; and
providing to an annular cooling passage, via the VB outlet, the amount of the variable bleed airflow in response to the data, the annular cooling passage extending between the CP inlet in airflow communication with the working gas flowpath of the turbomachine and a CP outlet in airflow communication with a bypass passage of the gas turbine engine, wherein the turbomachine defines an inlet to the working gas flowpath located downstream of the fan, wherein
a compressor section defines a first second stage of compression downstream of the inlet, wherein the CP inlet in airflow communication with the working gas flowpath at a location upstream of the first second stage of compression, wherein
no intermediate stages of compression are located between the first stage of compression and the second stage of compression, and wherein
the supplementary VB outlet is in direct airflow communication with the bypass passage and is separated and downstream from the CP outlet.
15 . The method of claim 14 , wherein the operating condition is a low fan power operating condition, and wherein varying the amount of variable bleed airflow through the variable bleed duct provided to the annular cooling passage comprises increasing the amount of variable bleed airflow through the variable bleed duct provided to the annular cooling passage.
16 . The method of claim 15 , wherein the low fan power operating condition is a ground idle operating condition or a flight idle descent operating condition.
17 . The method of claim 14 , wherein the operating condition is indicative of an ambient temperature.
18 . The method of claim 14 , wherein a variable bleed assembly comprises a variable bleed valve for varying the amount of the variable bleed airflow through the variable bleed duct.
19 . The method of claim 14 , wherein the turbomachine comprises a heat exchanger in thermal communication with an airflow through the annular cooling passage.