Pylon-mounted bottoming cycle

An aircraft propulsion system comprising:

• a core engine comprising a compressor, combustor, and turbine where a cryogenic fuel is mixed with compressed air from the compressor in the combustor and ignited to generate an exhaust gas flow that is expanded through the turbine to generate shaft power;
• a propulsive fan coupled to be driven by the turbine;
• a pylon configured to support the core engine and the propulsive fan, wherein the pylon comprises an interior space;
• a bottoming cycle supported within the interior space of the pylon, where the bottoming cycle comprises a working fluid that is circulated within a closed circuit comprising a bottoming compressor section and a bottoming turbine section, wherein the working fluid is compressed in the bottoming compressor section and expanded through the bottoming turbine section to drive a drive shaft;
• a primary heat exchanger configured to communicate thermal energy from the exhaust gas flow into the working fluid;
• a fuel system comprising a cryogenic fuel storage tank and a fuel flow path for routing a flow of the cryogenic fuel to the core engine;
• and
• a fuel/working fluid heat exchanger configured to transfer thermal energy from the working fluid to the flow of the cryogenic fuel.

A method of operating an aircraft propulsion system comprising:

• communicating thermal energy from a heat source into a working fluid within a primary heat exchanger to generate a heated working fluid flow circulating within a closed circuit of a bottoming cycle supported within an interior space of a pylon;
• generating shaft power with the bottoming cycle by compressing a flow of the working fluid that is communicated through the closed circuit from the interior space of the pylon to the primary heat exchanger and expanding the flow of the heated working fluid flow through a bottoming turbine section to drive a drive shaft;
• and
• cooling the flow of the working fluid with a flow of cryogenic fuel within a fuel/working fluid heat exchanger.