Closed-Loop Control of Separation in Subsonic and Transonic Flows

Clear Science Corp. and Syracuse University propose to design and demonstrate a closed-loop system for controlling flow separation on lifting surfaces over the transonic flight regime---offering the potential of significantly higher mission effectivenessin weapons like LOCAAS. Reduced-order models of the flow are required for control in real time, and these models must reflect the critical dynamics. Output to the feedback system must be physically measurable in realistic applications. Minimizing thepower requirements of an active flow control system means exploiting physical mechanisms that amplify the effects of small-scale input. Through open-loop experiments and simulations conducted by our team, we have demonstrated technology that utilizeswall-mounted sensors and pulsed jets to produce large-scale effects with small-scale input. In Phase I, we will integrate our proven technologies into candidate closed-loop control systems. We will evaluate controllers that combine low-dimensionalmodels, optimal design, and feedback control. We will evaluate sensor, actuator, and signal processor hardware based on performance, size, weight, cost, and power requirements. Controller evaluation willbe based on robustness over a range of conditions and adaptability to sensor noise, data latency, and model uncertainties. We will downselect components and a controller design for Phase II hardware-in-the-loop demonstrations at subsonic and transonicconditions.Increased performance requirements and tighter constraints on volume and weight force airframes closer to their design limits. Jet engine manufacturers must reduce surge margins for the same reasons. Airframe and propulsion system designers neednewtools for these new challenges and all stand to gain from an experimentally validated computational environment for designing systems for closed-loop control of flow separation.