Leading-edge slat is a main contributor to airframe noise. In some cases, intensive tonal noise can be generated. Previous studies assumed that one of the tones shared the same mechanism as the cavity tones. In this experimental research, a two-element wing was tested in the anechoic chamber at the University of Southampton. Results indicated that the most intensive tone was associated with the vortex shedding from the slat cusp. Plasma actuators were employed to suppress the tonal component. Significant reduction of the noise was achieved using the plasma actuator in an open loop setup. In addition, a mathematic model, which described the slat plant, was identified using a system identification technique. Based on this model, a Linear-Quadratic-Gaussian (LQG) servo controller was constructed and tested.
A slat is an aerodynamic device generally employed in multi-element airfoil configurations to increase the maximum lift. The main purpose of the slat is to reenergize the flow above the suction surface of the main element by providing high speed flow through the slat gap. However, employment of the slat leads to an unpleasant side-issue: slat noise. Several approaches which aim to attenuate the slat noise were proposed and verified over the last decade. To attenuate the slat noise without degradation of wing's performance, new techniques are increasingly demanded. Single dielectric barrier discharge (SDBD) actuator has been widely explored over the past decade because of the advantages it offers. The main advantage of a plasma actuator is that it directly converts electric energy into kinetic energy without any moving parts. This renders the actuator structurally simple. Another advantage is that the response time is short and can be employed in a real-time control.