Flutter analysis of a wraparound fin projectile considering rolling motion

Abstract

The aeroelastic stabilities of curved fins (or wraparound fins) in rolling motion are investigated in the supersonic flow region. Because of their inherent roll, wraparound fins are subjected to both aerodynamic and centrifugal forces. The aerodynamic force is computed by solving Euler equations in a body-fixed rotating coordinate frame. The normal mode analyses of the spinning structure are performed by using a multipurpose finite element code. For the consistent analysis a nondimensionalized aeroelastic equation considering the rolling motion is derived and aeroelastic parameters, such as velocity index and mass ratio, are devised. From the flutter analyses for wraparound fins, it is observed that the flutter characteristics with roll are very different from those without roll. It indicates that the consideration of the rolling motion must be made to predict the flutter stability accurately. Because of the geometric asymmetry of the wraparound fin, the flutter characteristics in each roll directions are different from each other. Flutter analyses indicate that there exists a more stable roll direction for flutter.