High pressure air source for aircraft and engine requirements

An apparatus for producing cooled air at relatively high, medium, and low pressures for use with components of a vehicle, said apparatus comprising

• a gas turbine engine having in serial flow arrangement a low pressure compressor and a high pressure compressor for compressing ambient air thereby producing compressed air, a combustor section for mixing fuel with said compressed air and igniting said fuel and compressed air to produce combustion products, a turbine section for expanding said combustion products and driving the low and high pressure compressors, an exhaust section for conveying said combustion products from said turbine section and out of said gas turbine engine, said high pressure compressor having an interstage bleed for extracting air therefrom at a bleed pressure significantly greater than the first pressure and significantly less than the second pressure, said high pressure compressor having an exit stage bleed for extracting air therefrom at a bleed pressure essentially equal to the second pressure, and said engine having a bypass duct extending between the low pressure compressor and the exhaust section for bypassing compressed air exiting the low pressure compressor around the high compressor, combustor section and turbine section;
• first and second heat exchangers located in said bypass duct, said first heat exchanger located between said second heat exchanger and said low pressure compressor, each heat exchanger having first and second flow paths extending therethrough, each flow path having an inlet and an outlet, said first flow path of each heat exchanger exposed to the compressed air exiting the low pressure compressor;
• and,
• an auxiliary unit including an auxiliary compressor having a compressor inlet port and a compressor discharge port, a first auxiliary turbine having a first turbine inlet port and a first turbine discharge port, a second auxiliary turbine having a second turbine inlet port and a second turbine discharge port, said first and second auxiliary turbines connected to said auxiliary compressor by a shaft to provide power thereto, a selector valve, a first conduit connecting said exit stage bleed to the selector valve, a second conduit connecting said interstage bleed to the selector valve, a third conduit connecting the selector valve to the inlet of the second flow path of the first heat exchanger, a fourth conduit connecting the outlet of the second flow path of the first heat exchanger to the compressor inlet port, a fifth conduit connecting the compressor discharge port to the inlet of the second flow path of the second heat exchanger, a sixth conduit connecting the outlet of the second flow path of the second heat exchanger to the first inlet port of the first turbine, a seventh conduit connecting the sixth conduit to components that utilize cool, relatively high pressure air, an eighth conduit connecting the first turbine discharge port to the inlet of the second turbine inlet port, a ninth conduit connecting the eighth conduit to components that utilize cool, relatively medium pressure air, and a tenth conduit connecting the second turbine discharge port to components that utilize cool, relatively low pressure air.