Flutter Characteristics of a Rolling Wraparound Fin Projectile Considering Aeroelastic Deflections

Abstract

The aeroelastic stabilities of rolling wraparound fins are investigated in the supersonic flow region. The aerodynamic forces are computed by solving the Euler equations in a body-fixed rotating coordinate frame. Aerodynamic influence coefficients are calculated using a transient pulse method. The nonlinear static and normal mode analyses for a rotating structure are performed using MSC/NASTRAN. To provide consistent analyses, nondimensionalized aeroelastic equations are derived and solved. The computational fluid dynamics/computational structural dynamics-coupled flutter analysis techniques, which can consider the initial aeroelastic deflections produced by the centrifugal and aerodynamic forces, are presented. A modal analysis and V-g method are used for more efficient computations. From the flutter analyses, it is observed that the flutter characteristics of rolling wraparound fins can be altered by considering the aeroelastic (or static) deflections that result from the rolling motion. Furthermore, wraparound fins, due to their geometrical shape, have different deformation shapes and dynamic characteristics depending on the rolling direction. Therefore, the aeroelastic deflections that result from the rolling motions should be considered to predict the flutter stability accurately.