Aerodynamic Analysis of a Transport Aircraft with a Boundary Layer Ingesting Aft-Propulsor at Cruise Flight Conditions

The implementation of advanced propulsion systems to ensure aviation meets the increasingly stringent environmental and economic pressures is a key building block in the development of future transport aircraft. A promising technology is the utilization of boundary layer ingesting (BLI) propulsion concepts, which are seen to offer an improvement of the engine propulsive efficiency in tandem with a reduction of the overall aircraft wake dissipation losses. In a collaborative study between the DLR Institute of Aerodynamics and Flow Technology, the DLR Institute of Propulsion Technology and industrial partners, a comprehensive study of the potential of implementing BLI concepts for future single-aisle short-to-medium range transport aircraft has been conducted. The present paper presents the result of an overall aircraft aerodynamic study, in which an aft BLI propulsor, specifically designed for this particular application, is investigated in its installation on the tail of a single aisle aircraft configuration at cruise flight conditions. A detailed aerodynamic analysis is presented, with a focus on comparing the results achievable through various BLI engine modeling approaches, which include the use of a classical engine boundary condition, a body force model as well as a full representation of the fan and OGV stage in a uRANS simulation approach. In addition to the study of the mutual aerodynamic interactions between the airframe and propulsor, some key aspects of the highest fidelity uRANS simulation approach are also discussed