The reduction of side force acting on a cone-cylinder slender body using a microballoon array actuator is examined. This microballoon array actuator can be inflated to a height of approximately 1.2 mm on the curve surfaces of the slender body. Experimental results indicate that side forces can be significantly reduced by inflating actuators near the weak and strong separated vortex structures. The mechanism of side force reduction has been investigated via both hot-wire and surface pressure measurements. Interestingly, unlike the conventional methods of changing the vortices from asymmetric to symmetric pairing for side force reduction, a microballoon array actuator makes vortices more asymmetric. It was found that two mechanisms can characterize the reduction of side force. The first mechanism involves that the weak side vortex lifts off prematurely because the microballoon actuation replaces the vortex pair structures with a more asymmetrically positioned pattern, enabling the formation of a new (third) vortex in the near-wall region. The second mechanism involves the strength of the newly generated (third) vortex being able to be effectively controlled via the microballoon actuation. Microballoon actuators can effectively alter the evolution of the new (third) near-wall vortex structure.

An exact analysis of deformation and stress field in a laminated elastic tube under extension and uniform pressuring is presented. The problem of finite laminated tube is considered with emphasis on the end effect. The problem is formulated on the basis of the state space formalism for axisymmetric deformation of transversely isotropic layer. The transfer matrix transmits the state vector in radial direction from inner surface to outer surface and takes into account the interfacial continuity and lateral boundary conditions in a rigorous manner. Upon delineating the symplectic orthogonality relations of the eigenvectors and by using eigenfunction expansion, an exact solution which satisfies the end conditions is determined. The results show that the end effect is significant but confined to a local region near the base where the displacement and stress distributions are remarkably different from those according to the simplified solutions that only satisfy lateral BC.