Development of an aerodynamic analysis tool for boundary layer ingestion concept design

The methods incorporated in an aerodynamic analysis tool are introduced to support aircraft conceptual designs, where a boundary layer ingestion (BLI) propulsion system is deployed. In order to integrate the BLI model to a generic tool for aircraft designs, two methods of approximating boundary layer profiles along the airframe/fuselage have been examined. For an airfoil-shaped wing/body configuration, the airfoil analysis program XFOIL is used and, alternatively, the flat plate boundary layer theory may be adopted. With the boundary layer characteristics approximated from these methods, the fan performance in terms of pressure ratio and efficiency is corrected considering the inflow distortion incurred by the boundary layer ingested, based on a simplified parallel compressor method. Given the corrected fan pressure ratio and efficiency, an equivalent velocity bookkeeping method is used for predicting the BLI fan performance in terms of power requirement and thrust generation. A validation against the boundary layer approximation is also presented in comparison with the RANS-based CFD simulations for a blended wing body (BWB) aircraft