Actively controlled transverse gas injection

In general the problem of feedback control for an unsteady fluid flow is nonlinear. Especially challenging is the control of mixing processes in a hot, potentially reactive environment. Because of the high temperatures present, realistic sensors can only operate mainly in cool regions, e.g., away from flames and hot exhaust regions. Consequently, there is often a large time lag between the time at which an actuator would modify, for example, a fuel or dilution air jet´s characteristics in a combustion chamber, and the time at which a sensor would measure the effect of this action on the jet´s mixing and/or reaction processes. During this time lag, flow dynamics, mixing, and combustion chemistry, if present, are dominated by nonlinear effects. A goal of the present study is to develop control strategies to optimize the mixing characteristics associated with the actively driven jet in crossflow. As a consequence of the differences between signal generator input function and jet exit velocity temporal variation (which is the actuation for the flowfield), it becomes necessary to design for the jet actuator a feedback controller which is distinct from the plant controller used for the overall experiment. Moreover, in developing a controller for the transverse jet problem there is an interesting trade-off between the complexity of actuating and sensing