Aerodynamic Design of Exo-Skeletal Engine Fan Blades

The aerodynamic feasibility of fan rotor blades for the revolutionary Exo-Skeletal Engine (ESE) is assessed for a subsonic mission using the NASA Engine Structures Technology Benefit Estimator (EST/BEST) computational simulation system. The ESE calls for the elimination of the shafts and disks completely from the engine center, and places the attachment of the rotor blades in spanwise compression to a rotating casing. The preliminary aerodynamic design of the fan rotor blade estimated an overall adiabatic efficiency of 91.8%. The flow is supersonic near the blade leading edge but quickly transitions into a subsonic flow without any turbulent boundary layer separation on the blade. The performance map for the fan rotor blade is calculated using a 2D off-design code. The results show that the ESE fan blade has reasonable stall and choke margins. It will be demonstrated in this paper that a computational simulation capability is readily available to evaluate new and revolutionary technology such as the ESE.