Study of the effects of wing sweep on the aerodynamic performance of a blended wing body aircraft

Abstract

This article presents a study of the effects of wing sweep on the aerodynamic performance of a blended wing body (BWB) aircraft that is based on an aerodynamically optimized design with a fixed planform and pitching moment constraint. Sixteen BWB geometries with varying wing sweep angles ranging from −40° (forward sweep) to 55° sweep were evaluated, while keeping the aerofoil profiles and twist distribution unchanged from the original optimized geometry. This gives some insight into the effects of one of the key planform design parameters. Numerical simulations were carried out using Euler solutions of the flow field with adaptive unstructured grids. Grid sensitivity studies were carried out, along with grid adaptation, on all geometries for solution accuracy. Results show that within 10° −55° sweep, there is significant variation in the lift-to-drag ratio ( LID), whereas for sweep values from −40° to 10°, the L/D ratio remained relatively constant. To maintain the design lift for varying wing sweep, the angle of attack of the aircraft needs to be changed. It was found that this variation followed an approximately parabolic curve, with a minimum incidence of 4.91° at 25° wing sweep. Furthermore, it was seen that the coefficient of moments versus the sweep angle varied almost linearly for all geometries under investigation.