Flow simulation and optimal shape design of N3-X hybrid wing body configuration using a body force method

System studies show that NASA's N3-X hybrid wing-body aircraft with a turboelectric distributed propulsion system using a mail-slot inlet/nozzle nacelle can meet the environmental and performance goals of N+3 generation transports (three generations beyond the current air transport technology level). In this paper, we present flow calculations and shape optimization of the integrated N3-X configuration, including the mail-slot propulsor, based on an unstructured-mesh Navier-Stokes solver. To simulate the propulsor fans flow, a novel body force model is suggested for a realistic and efficient representation of flow turning, pressure rise and losses resulting from the fan blades and the inlet-fan interactions for distorted inflow conditions. This work is the first of its kind analysis and design study on boundary layer ingestion inlet and fan interaction problems using the body force method. A mail-slot geometry was generated and installed on the N3-X configuration with an efficient CAD-free method. An optimal shape design of the mail-slot nacelle surface with the adjoint method was successfully conducted to reduce the strength of shock waves and flow separations on the cowl surface.