Flow Separation Control Using Slope Seeking With Extended Kalman Filter

Plasma actuator for flow control is a new technique developed in last decades. Inthis thesis, experimental study has been conducted to determine the controleffectiveness of a3-dimensional plasma actuator on a NACA0015airfoil section forflow separation control in an open-loop and closed-loop control system.Firstly, the characteristic of the NACA0015at two different Reynolds numberswas studied by measuring the time–average force of the airfoil at different AOA and theflow visualization technique. Based on these data, a brief understanding of the flowcharacteristic was achieved.Secondly, the novel design of the3-D plasma actuator consists of anarrangement of two serrated electrodes, with the peaks on each electrode facingopposite each other, horizontally separated by a dielectric material. In order tounderstand the control effectiveness of the3-D plasma actuator, both lift and dragmeasurements on a NACA0015airfoil were performed at two Reynolds numbers Re(0.77×105and1.54×105). The3-D plasma actuator showed effective controlperformance at Re=0.77×105: the stall angle is delayed for5degrees; the maximumlift coefficient is increased by6.26%; the total drag is reduced48%at AOA=15degrees;the maximum lift-to-drag ratio is increased by109.5%. At Re=1.54×105, themaximum drag reduction is44%at AOA=15degrees but the maximum lift coefficientjust have a little improvement. The mechanism of the control performance is discussed.Lastly, a closed loop control system is constructed using extended Kalman filter(EKF) based slope seeking and classical slope seeking algorithms at Re=0.77×105tocontrol the applied voltage of the3-D plasma actuator. It is found that both of thealgorithms can stabilize the applied voltage near the optimal voltage. The controlauthorities of the two methods are compared, which shows that the EKF based slopeseeking method has a shorter settling time compared with the classical slope seekingmethod.