Flutter Suppression using Synthetic Jet Actuators: the Typical Section

摘要

Synthetic jet actuators (SJA) are among the most promising devices for adaptive flow control. These zero net mass flux actuators periodically force fluid through an orifice in and out of a cavity located inside the body close to surface. Typical applications of SJA are in boundary layer control through momentum exchange improving boundary layer stability, delaying transition, and separation. A less recognised effect of SJA on the flow field also is that momentum exchange with the flow leads to a rearrangement of the streamlines around the airfoil modifying the aerodynamic forces and moments. This phenomenon is called dynamic virtual shaping. In spite of the complexity of the flow fields generated by synthetic jet actuators, reduced order models (ROMs) capable of accurately predicting the unsteady aerodynamic forces and moments generated by the actuators have been developed and verified. In this paper, flutter suppression using SJAs is investigated employing these ROMs. The study considers a typical airfoil section in incompressible flow and feedback control is used to stabilise the airfoil at airspeeds higher than its flutter speed, thus increasing the stable flight range. Numerical calculations indicate that the flutter boundary can be successfully moved to higher airspeeds and that the required control authority is sensitive to the tuning of the SJA eigenfrequency to the flutter eigenfrequency. In addition, preliminary investigation of the performance of SJA control for load alleviation is performed indicating limited capability in rejecting disturbances due to atmospheric turbulence.