Closed-loop control of forebody flow asymmetry

A closed-loop digital control system was designed for a tangent-ogive forebody model to control the flow asymmetry during an unsteady pitching maneuver using suction ports located at the tip of the forebody. A feedback control system was also developed to control the coning angle phi of a coning motion model. The performance of both linear and nonlinear control laws was studied and evaluated. The controllers designed for the pitching forebody model were most effective for angles of attack less than 50 deg. For alpha > 50 deg, the controllers had difficulty in maintaining the pressure coefficient near the desired value of zero, which corresponded to a symmetric vortex configuration. The control system designed for the coning motion model enabled the model to perform a variety of different maneuvers. Experiments demonstrated the ability of the system to control the coning angle of the model, its rotation rate, and the direction of rotation.