Closed-Loop Flow Control of a Forebody at a High Incidence Angle

Abstract

The flowfield around an axisymmetric forebody at a high angle of attack () produces a significant side force. This side force results from an asymmetric pressure distribution around the body due to an asymmetric vortex configuration. Numerical studies of open-loop control using mass blowing slots near the tip of the model have shown a proportional response of the side force over a range of momentum coefficient amplitudes. From the open-loop simulations, a prediction-error minimization method was employed to formulate a linear time-invariant model, which captured the dynamics of the side force response to different mass flow rates applied to either the port or starboard actuator. Based on the linear time-invariant model, a proportional–integral control law was developed for set-point tracking a prescribed side force. The development of the linear time-invariant model, and corresponding linear time-invariant feedback solution are presented to illustrate the model’s capabilities and limitations. The ability to track a set-point signal based on the linear time-invariant model and corresponding proportional–integral control law are shown. The results indicate that the bandwidth of the controller is limited to frequencies below the convective frequency due to the convective time delay. Finally, the linear time-invariant feedback solutions are compared to Navier–Stokes feedback simulations, which show very good agreement.