Predictions of the Low-Speed Aerodynamic Characteristics of Generic UCAVs

At low speeds, the leading-edge sweep angle influences the flight performance of swept wings. The flow behavior of the moderate to highly swept wings is affected by the vortex flow structures, which form at low angles of attack because of leading-edge flow separation. This topic of investigation gained momentum recently due to its application to unmanned combat aerial vehicle (UCAV) configurations that are significantly affected by flow separation at high angles of attack. The present work investigates the flowfield and low-speed aerodynamic characteristics of the generic UCAV models with constant and non-constant leading-edge sweep for a wide range of angles of attack. The open-source computational fluid dynamics (CFD) code OpenFOAM 8.0 was employed for the numerical simulations. The present numerical simulation results matched well with the experimental data in the literature. It was found that the lift and drag characteristics of the UCAV are sensitive to the leading-edge sweep angle, and a non-constant leading-edge sweep angle variant exhibited delayed stall and enhanced aerodynamic performance.