Aerodynamic Flow Control of Axisymmetric Bluff Body by Coupled Wake Interactions

摘要

The stability and steering of nonspinning airborne bodies of revolution have traditionally relied on stationary or moving fins that affect controlled interactions with the oncoming flow to modify the inherent aerodynamic loads. An alternative approach for manipulation of these loads in the absence of external control surfaces can be realized by exploiting the reciprocal coupling between a moving bluff body and its near wake by either breaking or restoring the natural azimuthal near-wake symmetry using segmented fluidic actuation. The present paper reviews fluidic actuation of the near-wake dynamics by using an azimuthally segmented four-quadrant array of aft-facing synthetic jet modules around the tail end of an axisymmetric bluff-body model. Each actuator controls a segment of the aft separated vorticity layer using a hybrid configuration with a passive Coanda surface. The actuation allows for controlled suppression or enhancement of near-wake asymmetries and consequently of the associated aerodynamic forces and moments on a stationary model and in rigid-body motion. It is shown that the effects of actuation on the near-wake and aerodynamic loads of the static body are comparable to the effects of its combined pitch and yaw motions in the absence of actuation. The actuation provides significant suppression and augmentation of the motion-induced aerodynamic loads with concomitant controlled deflection or decoupling between the motions of the body and its near wake. It is anticipated that controlled manipulation of these fundamental coupling mechanisms can lead to active control of the motion and stability of flight platforms.