Modulated cooled P3 air for impeller
AssigneePratt & Whitney Canada Corp.
InventorXiaoliu Liu
Life of this patent
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Abstract
A method and apparatus using a cooler to selectively cool P3 air directed into an impeller rear cavity of a gas turbine engine during engine high power levels, may include connection of the cooler to a low pressure compressor bleed-off valve apparatus that is modulated to be closed during engine high power levels to create a pressure differential over the bleed-off valve apparatus, to drive a stream of low pressure compressor air as a cooling work fluid under such pressure differential to selectively flow through the cooler.
Claims10
A gas turbine engine comprising a compressor section, including:
- a bleed-off valve connected in a bleed-air flow passage, for selectively bleeding low pressure air from the compressor section through the bleed-air flow passage to an outlet of an exhaust duct when the bleed-off valve is open, the outlet disposed downstream of a turbine section;
- a cooler having a first passage connected to the bleed-air flow passage in parallel with the bleed-off valve to allow a stream of said low pressure air to flow through the cooler and to bypass the bleed-off valve when the bleed-off valve is closed, the cooler having a second passage for directing a stream of high pressure air bled from a plenum around a combustion chamber through the cooler before delivering the stream of said high pressure air to an impeller rear cavity formed behind an impeller hub of the compressor section, the stream of said high pressure air having a higher pressure than the stream of said low pressure air;
- wherein the stream of said low pressure air through the first passage of the cooler is modulated by the bleed-off valve parallel to the first passage of the cooler, so as to selectively cool the stream of said high pressure air flowing through the second passage of the cooler with the stream of said low pressure air;
- and
- a controller configured to control the bleed-off valve such that the bleed-off valve is closed during engine high power and is open during engine low power.
A method of cooling an impeller of a compressor of a gas turbine engine, the method comprising:
- bleeding low pressure air from the compressor of the gas turbine engine through a bleed-air flow passage, the bleed-air flow passage in fluid communication with a first passage of a cooler;
- bleeding a stream of high pressure air from a plenum around a combustion chamber, the stream of said high pressure air having a greater pressure than the low pressure air;
- continuously circulating the stream of said high pressure air through a second passage of the cooler to a cavity adjacent a hub of the impeller;
- and
- modulating a cooling of the stream of said high pressure air in the cooler by modulating a flow of the low pressure air bypassing the first passage of the cooler while flowing through the bleed-air flow passage to exit the bleed-air flow passage downstream of a turbine section of the gas turbine engine, wherein modulating the flow of the low pressure air bypassing the first passage of the cooler while flowing through the bleed-air flow passage includes selectively opening and closing a bleed-off valve of the bleed-air flow passage, the bleed-off valve being connected to the bleed-air flow passage in parallel with the first passage of the cooler, including closing the bleed-off valve during engine high power levels and opening the bleed-off valve during engine low power levels.
Dependencies are inferred from the claim text.