Gas turbine engine reverse bleed for coking abatement
A turbine engine includes: a core cowl, a core within the core cowl, the core including a compressor having a bleed port; an undercowl space; a cooling duct at least partially in the undercowl space and having an inlet and an outlet, the inlet communicating with a source of cooling air, the outlet communicating with the compressor bleed port; a valve assembly in the cooling duct; and a cooling blower operable to move air flow from the inlet of the cooling duct towards the outlet of the cooling duct and into the compressor bleed port. A method of cooling an engine having a core cowl and a compressor, combustor and turbine includes: operating the engine; shutting the engine down; after or during engine shutdown, operating a cooling blower internal to the engine cowl, to force air through the compressor by way of a compressor bleed port.
1. A method, comprising:
using an engine comprising a cowl, an undercowl space, a compressor in fluid communication with a downstream combustor and turbine, and a compressor bleed port;
at a time when the engine is operating, substantially preventing airflow from the compressor bleed port to the undercowl space;
at a time when the engine is shut down, permitting airflow from the undercowl space to the compressor and operating a cooling blower located internal to the cowl to cause the airflow from the undercowl space to flow into the compressor bleed port.
2. The method of claim 1 , wherein:
the step of substantially preventing the airflow includes positioning one or more valves in a closed position; and
the step of permitting airflow includes positioning the one or more valves in an open position.
3. The method of claim 2 , wherein the one or more valves are positioned in the closed position in response to fluid pressure generated by the engine during operation, and the one or more valves are positioned in the open position in response to absence of fluid pressure generated by the engine.
4. The method of claim 2 , further comprising, when the engine is operating:
admitting engine bleed air into the cooling duct from the compressor bleed port;
directing some of the engine bleed air out of the cooling duct away from the one or more valves in order to reduce a pressure differential across at least one of the valves; and
admitting cooling airflow from a cooling source into the cooling duct between at least one of the valves and the cooling blower and mixing the cooling airflow with the bleed air so as to reduce the temperature of the engine bleed air prior to it contacting the cooling blower.
5. The method of claim 1 , further comprising, prior to operating the cooling blower, determining that the engine is shut down by reference to at least one sensor signal associated with an aircraft.
6. The method of claim 1 , wherein the cooling blower is operated for a predetermined amount of time after the engine is shut down.
7. The method of claim 6 , wherein the predetermined amount of time is computed using an electronic engine controller of the engine in response to at least one sensor input.
8. The method of claim 7 , wherein:
the engine is mounted in an aircraft;
the predetermined amount of time is communicated to an electronic aircraft controller of the aircraft from the engine controller; and
in response to the communication from the electronic engine controller, the electronic aircraft controller provides power to the cooling blower for the predetermined amount of time.
9. The method of claim 1 , wherein the airflow permitted from the undercowl space to the compressor bleed port flows through at least a portion of a flowpath of the engine.
10. The method of claim 1 , wherein:
the engine is mounted in an aircraft;
a requirement for cooling is communicated to an electronic aircraft controller of the aircraft from an engine controller; and
in response to the communication from the engine controller, the electronic aircraft controller provides power to the cooling blower.
11. The method of claim 1 , further comprising, prior to operating the cooling blower, determining that the engine is shut down by reference to at least one sensor signal associated with the engine.
12. A method, including:
using an engine comprising a core cowl, an undercowl space, and a compressor in fluid communication with a downstream combustor and turbine, the compressor having a compressor bleed port in a casing that defines a compressor flowpath;
operating the engine;
shutting the engine down; and
after or during engine shutdown, operating a cooling blower internal to the core cowl, to force air through at least a portion of a flowpath of the engine by way of the compressor bleed port.
13. The method of claim 12 , wherein the air forced through the flowpath also flows through the undercowl space.
14. The method of claim 13 , wherein the cooling blower is operated for a predetermined amount of time, and the predetermined amount of time is computed using an electronic engine controller of the engine in response to at least one sensor input.
15. The method of claim 14 , wherein:
the engine is mounted in an aircraft;
the predetermined amount of time is communicated to an electronic aircraft controller of the aircraft from an engine controller; and
in response to the communication from the engine controller, the electronic aircraft controller provides power to the cooling blower for the predetermined amount of time.
16. The method of claim 12 , wherein:
the engine is mounted in an aircraft;
a requirement for cooling is communicated to an electronic aircraft controller of the aircraft from the engine controller; and
in response to the communication from engine controller, the aircraft controller provides power to the cooling blower.
17. The method of claim 12 , further comprising:
at a time when the engine is operating, positioning one or more valves in a closed position, so as to block airflow between the cooling blower and the compressor bleed port;
at a time when the engine is shut down, positioning the one or more valves in an open position to permit airflow from the cooling blower to the compressor bleed port.
18. The method of claim 12 , further comprising, prior to operating the cooling blower, determining that the engine is shut down and on the ground by reference to at least one sensor signal associated with an aircraft.
19. The method of claim 18 , wherein one or more valves are positioned in a closed position in response to fluid pressure generated by the engine during operation, and the one or more valves are positioned in an open position in response to absence of fluid pressure generated by the engine.
20. A method, comprising:
using an engine comprising a cowl, an undercowl space, a compressor in fluid communication with a downstream combustor and turbine, and a compressor bleed port in a casing that defines a compressor flowpath;
at a time when the engine is operating, substantially preventing airflow from flowing through the bleed port;
at a time when the engine is shut down, permitting airflow through the compressor bleed port and operating a cooling blower located internal to the cowl to cause air to flow into the compressor bleed port.
21. The method of claim 20 , wherein:
the step of substantially preventing airflow includes positioning one or more valves in a closed position; and
the step of causing air to flow into the compressor bleed port includes positioning the one or more valves in an open position.
22. The method of claim 21 , wherein the one or more valves are positioned in the closed position in response to fluid pressure generated by the engine during operation, and the one or more valves are positioned in the open position in response to absence of fluid pressure generated by the engine.
23. The method of claim 21 , further comprising, when the engine is operating:
admitting engine bleed air into the cooling duct from the compressor bleed port;
directing some of the engine bleed air out of the cooling duct away from the one or more valves in order to reduce a pressure differential across at least one of the valves; and
admitting cooling airflow from a cooling source into the cooling duct between at least one of the valves and the cooling blower and mixing the cooling airflow with the bleed air so as to reduce the temperature of the engine bleed air prior to it contacting the cooling blower.
24. The method of claim 20 , further comprising, prior to operating the cooling blower, determining that the engine is shut down by reference to at least one sensor signal associated with an aircraft.
25. The method of claim 20 , wherein the cooling blower is operated for a predetermined amount of time after the engine is shut down.
26. The method of claim 25 , wherein the predetermined amount of time is computed using an electronic engine controller of the engine in response to at least one sensor input.
27. The method of claim 26 , wherein:
the engine is mounted in an aircraft;
the predetermined amount of time is communicated to an electronic aircraft controller of the aircraft from the electronic engine controller; and
in response to the communication from the electronic engine controller, the electronic aircraft controller provides power to the cooling blower for the predetermined amount of time.