Next-generation aircraft and missile are required to have extreme maneuverability, which should maintain stability at high angle of attack. However, the unsteady flow field surrounding the air vehicle would affect the aerodynamics loads and induce unwanted nonlinear motions, of which the rolling motions are usually generated. In order to investigate the unsteady rolling characteristics of a cruciform-finned slender body, the free-to-roll and force measurement tests including particle image velocimetry measurement have been conducted comprehensively. Different types of rolling motion, trimming at equilibrium positions, self-excited rolling oscillation, and self-excited spinning are observed during the free-to-roll experiment depending on the different angles of attack. The force measurement results show that the rolling motions are related to both the static and dynamic stabilities of the rolling moment at balance points. The stabilities of the rolling moment would change as the angle of attack for the model increases. At last, the flow field results from particle image velocimetry measurement indicate that the unsteady rolling motions may be induced by the interaction between the asymmetry vortices and strake wings, fins.
Particle-image velocimetry measurement errors when imaging through a transparent engine cylinder
