Optimization of burst frequency using extremum-seeking method for flow control by PSJA

Abstract

In this paper, we study the optimization of the burst frequency applied to the plasma synthetic jet actuator (PSJA) using extremum-seeking method. Experiments were performed to detect the optimum frequency that maximizes the effect of reducing flow separation around an NACA0015 airfoil. The burst input is expected to improve the effect of flow control and to reduce the power consumption. The optimality is determined based on the correlation of the modulation frequency and the wake velocity. The optimum frequency was searched in the interval from 30Hz to 310Hz and was detected within few seconds. The main flow velocity was set from 5m/s to 10m/s and the angle of attack was fixed at 10deg and 15deg. For 15deg angle of attack, the multiple frequencies were detected as local maximums under each main flow velocity. We found that the flow velocity is maximized at around 50Hz burst frequency for 9m/s main velocity and 15deg angle of attack. At this frequency, the flow velocity is approximately 37% higher than the minimum velocity over the search region of the modulation frequency. The optimum non-dimensional frequencies are in the range from 0.3 to 2.5. For 10deg angle of attack, the flow velocity monotonically increases with respect to the modulation frequency at all main flow velocities.

Keywords

• flow control
• extremum seeking
• plasma synthetic jet actuator
• burst wave
• optimum frequency