Thermodynamic performance and decoupling characteristics analysis of a dual-shaft hybrid propulsion system integrated solid oxide fuel cell for commercial aircraft

Commercial aircraft today face the challenge of reducing carbon emissions and fuel consumption while ensuring flexible control of propulsion systems under complex flight conditions. This study proposes a dual-shaft fuel cell hybrid aircraft propulsion system (HAPS), which replaces the turbine with a solid oxide fuel cell (SOFC) to power the compressors. The innovative aspect of this system lies in the use of a variable power distribution system that allows for decoupled control of the high-pressure (HP) and low-pressure (LP) spool speed. A mathematical model of HAPS is developed, considering both performance and weight, achieving a thrust of 37.669 kN and a specific fuel consumption of 17.309 g/s/kN at the design point. The main conclusions are as follows: (1) The system demonstrates overall superior performance compared to the turbofan engine, with the exception of a lower propulsion efficiency due to the increased exhaust velocity. (2) By adjusting the power distribution ratio (PDR), the optimal thrust and specific fuel consumption of the HAPS are improved by 0.56 % and 4.20 %, respectively, compared to the HAPS without the variable power distribution system. (3) Despite the relatively large weight of HAPS, 6909.84 kg under the maximum static thrust design, it shows potential for application in commercial aircraft through integrated design approaches. This study lays the foundation for the future application of hybrid propulsion systems in commercial aviation.