Investigating the benefit of aerodynamic shape optimization for a wing with distributed propulsion

Abstract Recent interest in urban and regional air mobility and the need to improve the aviation industry’s emissions has motivated research and development of novel propeller-driven vehicles. These vehicles range in configuration from conventional takeoff and landing designs to complex rotorcraft that transition between vertical and horizontal flight. These designs must be optimized to ensure optimal efficiency throughout their missions, leveraging the tightly coupled nature of propeller-wing interaction. In this work, we study the NASA tiltwing concept vehicle wing with varying numbers of propellers, ranging from no propellers to five propellers evenly spaced along the wing. Using aerodynamic shape optimization, we optimize the wing shapes for each propeller-wing configuration, minimizing the wing drag. These optimizations are carried out with DAFoam, a discrete adjoint implementation of OpenFOAM, embedded within OpenMDAO and the MPhys optimization framework. The optimizations show that the lowest drag configuration is a single propeller mounted at the wing tip. Increasing the number of propellers slightly increases drag compared to the single propeller configuration. However, aerodynamic shape optimization considering propeller-wing interaction yields a negligible benefit compared to aerodynamic optimization of an isolated wing that is subsequently trimmed to a desired flight condition in the presence of a propeller.