Low-Speed Performance Analysis of Double Swept Waverider with Wing Dihedral

Abstract

The double swept waverider offers superior performances in subsonic states while retaining a high lift-to-drag (L/D) ratio in hypersonic state, thus overcoming some deficiencies of the traditional waverider. However, it still has some flaws such as poor stability. In this study, the waverider design given a three-dimensional (3D) leading edge was developed from the osculating-cone treatment. Consequently, the double swept waveriders with wing dihedral and anhedral were generated by customizing the leading-edge curves, which shared the same planform shape. Using computational fluid dynamics (CFD) techniques, the low-speed performances of these waveriders were analyzed, including the lift and drag characteristics and vortex structure. The effect of the wing with positive and negative dihedral angles, namely the wing dihedral and wing anhedral, on stability was also studied. Results show that the configurations with wing dihedral and anhedral had nearly an identical L/D ratio to the configuration whose projection in the front-view direction was horizontal. These configurations were all unstable in longitudinal static stability with similar pitching moment. With wing anhedral, the aerodynamic center moved backward, increasing longitudinal stability to a slight extent. The wing dihedral improved the lateral stability, while wing anhedral decreased it. Wing dihedral improved the directional stability with a stronger effect at higher dihedral angles. Wing dihedral raised the lateral-directional dynamic stability of the waveriders obviously, while wing anhedral decreased it, and the effects were positive correlation to the extent of wing tips going up and down. According to these results, wing dihedral and anhedral are feasible to improve the low-speed stability of a waverider, providing a novel approach to design wide-speed hypersonic vehicles.