Design of a Morphing Airfoil Using Aerodynamic Shape Optimization
An in-house high-fidelity aerodynamic shape optimization computer program based on a computational fluid dynamics solver with the Spalart-Allmaras turbulence model and a sequential-quadratic-programming algorithm is used to obtain a set of optimal airfoils at the different flight conditions of a light unmanned air vehicle. For this study, the airfoil requirements at stall, takeoff run, climb gradient, rate of climb, cruise, and loiter conditions are obtained. Then, the aerodynamic shape optimization program is used to obtain the airfoil that has the optimal aerodynamic characteristics at each one of these flight conditions. Once the optimal airfoils at each flight condition are obtained, the results are analyzed to gain a better understanding of the most efficient initial airfoil configuration and the possible mechanisms that could be used to morph the single element airfoil. The results show that a very thin airfoil could be used as the initial configuration. Furthermore, a morphing mechanism that controls the camber and leading-edge thickness of the airfoil will almost suffice to obtain the optimal airfoil at most operating conditions. Lastly, the use of the optimal airfoils at the different flight conditions significantly reduces the installed power requirements, thus enabling a greater flexibility in the mission profile of the unmanned air vehicle.