There is much current interest in the use of feedback control to control complex fluid flows. This work focuses on using feedback control to stabilize a round turbulent air jet/diffuser undergoing transitory stall at Reynolds number based on the exit throat diameter of Re_D = 20,000 to Re_D = 25,000. Two types of actuation axe used as the control actuators to stabilize the jet/diffuser flow. System identification techniques axe used to model the input-output response of the complex turbulent flow as a simple linear model. The model represents the deterministic input-output response, while the non-deterministic response is treated as noise by the control law. Second order input-output models axe implemented in a model based control law and are effective at lowering the low frequency disturbances corresponding to the transitory stall.

A computer simulation was used in designing the control law and also allows the variation of parameters that cannot easily be varied experimentally. The consequence of time delay, actuator effectiveness, and noise levels on the controller performance are examined both by simulation and experimentally. These effects axe examined from a physical perspective and the results from the jet/diffuser flow are generalized to a larger class of flows.