Gas turbine engines with a fuel cell assembly

An aircraft engine comprising:

• a compressor section comprising a compressor;
• a turbine section downstream of the compressor section, the turbine section including a turbine having turbine blades arranged in counter rotating stages, the turbine blades including one or more stages of first-direction turbine blades and a single stage of second-direction turbine blades located downstream of the first-direction turbine blades, wherein the single stage of second-direction turbine blades is directly downstream of the first-direction turbine blades and is the only stage of second direction turbine blades of the turbine, and wherein a first shaft couples the one or more stages of first-direction turbine blades to a gearbox and a second shaft couples the single stage of second-direction turbine blades to the gearbox;
• and
• one or more fluid supply lines;
• a fuel cell assembly fluidly coupled to the one or more fluid supply lines for receiving one or more input fluids, wherein the fuel cell assembly is in fluid communication with the turbine section to provide one or more output products to one of the turbine section;
• and
• a heat recovery system comprising:
• a thermal transfer bus;
• a heat source exchanger disposed in fluid communication on the thermal transfer bus and positioned downstream of the counter rotating stages;
• and
• a heat sink exchanger disposed in fluid communication on the thermal transfer bus and positioned upstream of the fuel cell assembly, wherein the heat sink exchanger is thermally coupled to the one or more fluid supply lines of the fuel cell assembly.