Flow physics and boundary layer optimization over a NACA airfoil by camber morphing at subsonic speeds

In this paper, the variable camber morphing strategy is adopted in a NACA airfoil through computational investigation to enhance the lift to drag ratio (L∕D) specifically for military UAV applications. The typical mission profile is also focused on enhancing the aerodynamic performance of the UAV during various flight segments by variable camber morphing. The airfoil camber is changed dynamically at different instances based on the mission profile requirements thereby altering the L∕D characteristics. The concept of bio-inspired aerodynamics has received a greater attention in recent years because of the proven nature oriented real-time application. Hence, the concept of bio-inspired variable camber morphing is proposed herein that minimizes the use of unconventional control surfaces to attain the required performance at different segments of flight. MQ9 Reaper UAV model is chosen to implement the proposed variable camber morphing strategy at the mission flight segments. NACA 4412 cambered airfoil has been considered as the baseline model airfoil for the present study because of its higher zero lift angle characteristics. The lower camber of the airfoil section is changed from 1% to 3% at different angles of attack (AoA) for the time instances such as 1s, 2s and 3s, respectively. The lift coefficient (Cl) of the airfoil is also significantly increased through camber morphing at different flight segments during each time step with negligible flow separation as observed through streamline patterns. Hence, the friction drag coefficient is also retained under optimum level as concluded through the boundary layer profiles.