Design Exploration of Compressible Airfoils at Static and Dynamic Conditions

This paper presents a multi-fidelity aerodynamic optimization of airfoils subjected to unsteady kinematics at compressible flow conditions representative of high-speed rotorcraft operation. The study targets the outboard region of rotorcraft blades where the blade sections experience highly compressible speeds and periodic pitching in forward flight. A multi-objective optimization framework is employed, combining a steady Euler solver, MSES, for rapid, mid-fidelity design space exploration and a high-fidelity unsteady Reynolds-averaged Navier--Stokes solver, TURNS2D. Airfoils are parameterized using the class-shape transformation (CST) method and optimized under both steady and oscillatory flow conditions. The results highlight how incorporating unsteady kinematics, transition modeling and compressibility effects in the design loop results in laminar flow airfoils for the static case, and thin, highly cambered airfoils with some degree of laminar flow for the pitching with constant freestream and fluctuating freestream optimizations.