Flow Control of Tiltrotor Unmanned-Aerial-Vehicle Airfoils Using Synthetic Jets

Flow control using synthetic jets has been computationally investigated to improve aerodynamic performance of tiltrotor unmanned-aerial-vehicle airfoils under various flight conditions. Many features of complex tiltrotor flows were captured, including wing leading-edge and trailing-edge separation and the massive region of separated flow beneath the wing. To control the separation of the leading and trailing edges in hovering and transition-flight modes, synthetic jets were located at suitable positions (0.01c, 0.3c(flap), and 0.95c(flap)). It was observed that the flow structure and rate of drag reduction could be substantially improved, depending on the frequency of synthetic jets in hovering mode. Based on the flow control results in hovering mode, separation control was performed at transition mode. Detailed computations revealed the download could be efficiently reduced by using both the leading-edge and trailing-edge jets in hovering flight mode, and the leading-edge jet only in transition-flight modes. This indicates that the flight performance of tiltrotor unmanned aerial vehicles could be remarkably improved by applying an active flow control strategy based on synthetic jets.