Conceptual study of a mechanically integrated parallel hybrid electric turbofan

In the paper, options for mechanically integrated parallel hybrid propulsion are evaluated, and a conceptual sizing and performance study of a mechanically integrated parallel hybrid electric turbofan engine for a short-range aircraft application is presented and discussed. Through a methodical down-selection procedure, a most promising power plant system architectural concept is identified from an initial cloud of concept candidates. The design of the preferred configuration is conceptualized including initial performance analyses, both at the isolated power plant as well as at the integrated aircraft level. Beside the basic power plant definition, the multidisciplinary concept elaboration includes solutions proposed for the electric systems architectural layout, the major electrical components involved as well as important airframe integration aspects. The components of the electrical power management and distribution system are sized, and efficiency and weights are evaluated under special consideration of thermal management requirements. In result, a best and balanced degree of power hybridization is determined for the studied mechanically integrated parallel hybrid power plants taking account of electric system design and weight impacts as well as power plant operational robustness in case of electric system failure. The overall system assessment includes the evaluation of fuel reduction potentials through a parametric aircraft sizing study including the derivation of key technological requirements for onboard electrical energy storage. In the paper, essential design and sizing strategies for mechanically integrated parallel hybrid aero propulsion systems are derived, and a brief characterization of the associated key technological challenges is provided.