EFFECT OF DIHEDRAL WING ON LOW SPEED PERFORMANCE OF DOUBLE SWEPT WAVERIDER

The double swept waverider has advantageous performances in subsonic characteristics and nonlinear vortex lift, while maintaining the high lift-to-drag ratio in hypersonic state, overcoming some deficiencies of the traditional waverider. However, it still has some defects such as poor low-speed stability. The waverider design given a 3D leading edge is developed from the osculating-cone treatment, and the double swept waveriders with wing dihedral and anhedral were generated by customizing the leading edge curves, which shared the same planform shape. Using CFD techniques, the low speed performances of the waveriders were evaluated, the lift drag characteristic and vortex structure were analyzed, and the effect of the wing with positive and negative dihedral angles, namely wing dihedral and wing anhedral, on stability was also studied. Results show that compared with the configuration whose projection in the front-view direction was a horizontal line, the configurations with wing dihedral and anhedral had nearly the identical lift-to-drag ratio. Different configurations were all unstable in longitudinal static stability, and the pitching moment of these configurations were similar. With wing anhedral, aerodynamic center moved backwards, increasing longitudinal stability; the wing dihedral improved the directional stability, while wing anhedral decreased it; wing dihedral improved the lateral stability, and the effect was stronger with higher wingtips. The dynamic directional stability of the waveriders can be improved by the wing dihedral obviously, while wing anhedral decreased it, and the effects was positive correlation to the distance of wingtips went up or down. According to the results, it was feasible to improve the low-speed stability of waverider by wing dihedral and anhedral, and the method provides a novel way to design the wide-velocity-range hypersonic vehicles.