Nonlinearity Analysis of Increase in Lift of Double Swept Waverider

Abstract

The double swept waverider is a classic example of the planform-customized osculating-cone waveriders, delivering satisfactory performances over a wide range of velocities. The nonlinear increase in the lift of double swept waveriders at high angles of attack is of vital interest. In this paper, the aerodynamic performance of the double swept waverider is calculated and compared with single swept waveriders. The results suggest that the nonlinear increase in the lift of the double swept waverider is stronger than that of the equal-planform-area single swept waverider, and it increases with the Mach number. Some scholars have proposed the “vortex lift” to explain the nonlinear increase in lift, but it is controversial because the main lift of the waverider comes from the lower rather than the upper surface. This paper proposes that this nonlinear increase is related to the attachment of the shock wave influenced by the leading-edge sweep angle. The shock wave is more inclined to attach under the lower surface at a smaller sweep angle than a larger one as the angle of attack increases. When the shock wave attaches, the increase in pressure via the angle of attack is nonlinear, leading to a nonlinear increase in lift. When the shock wave detaches, the increase in lift is approximately linear.