Slope-Seeking Control for Stall Mitigation of a NACA0015 Airfoil
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This paper aims to investigate the response of the slope seeking with extended Kalman filter (EKF) deployed in a closed-loop system for airfoil aerodynamics control. A novel dielectric barrier discharge (DBD) sawtooth plasma actuator is used to manipulate the flow around the NACA 0015 airfoil. The sawtooth plasma actuator leads to a delay in the stall angle by 5° and an increase in the maximum lift coefficient by about 9 %, appreciably better than that with the “traditional” DBD plasma actuator of the same input power. For the closed-loop control, the convergence time t c of the lift force F L is investigated for two control algorithms from Re = 4.4 × 104 to 7.7 × 104. The t c is about 70 % less under the slope seeking with EKF than that under the slope seeking with high-pass (HP) and low-pass (LP) filters at Re = 7.7 × 104. The slope seeking with EKF shows excellent robustness over a moderate Re range; that is, the voltage amplitude determined by the control algorithm promptly responds to a change in Re, much faster than that of the conventional slope seeking with HP and LP fliters.
KeywordsFlow control Closed-loop control Slope seeking Plasma actuator
CW WONG wishes to acknowledge support given to him from Research Grants Council of Shenzhen Government through grants JC201105160543A and JCYJ20130402100505796.