Suppression of Resonance Tones in Shallow Cavities: A Case Study in Aerodynamic Flow Control

Systems Conversation with Andrea Serrani, Department of Electrical and Computer Engineering, The Ohio State University

Andrea summarizes the research activity of the Gas Dynamics and Turbulence Lab at The Ohio State University that has been devoted to the design and experimental evaluation of model-based feedback controllers for suppressing subsonic cavity resonance. Proper orthogonal decomposition and Galerkin projection techniques were used to obtain a reduced-order model of the flow dynamics from experimental data. The model was made amenable to control design by means of an optimization-based control separation technique, which makes the control input appear explicitly in the equations. An adaptive feedback controller was then employed to suppress the cavity tones from pressure measurements. Experimental results, in qualitative agreement with the theoretical analysis, showed that the controller achieves a significant attenuation of the resonant tone with a redistribution of the energy into other frequencies. The benefits of parameter adaptation over controllers of fixed structure under varying or uncertain flow conditions were also demonstrated experimentally. Finally, an outlook into application of closed-loop strategies for jet noise mitigation is offered.