Numerical aerodynamic simulations of a NACA airfoil using CFD with block-iterative coupling and turbulence modelling

Numerical aerodynamic simulations are presented for a National Advisory Committee for Aeronautics (NACA) airfoil that is stationary and pitching at high Reynolds numbers. A new improved CFD method based on block-iterative coupling is used with a computational scheme for fluid-structure interaction, in which a form of two-equation RANS turbulence model is adopted. Firstly, basic simulations were performed using the proposed CFD method and turbulence model, which provides good prediction of the airfoil force coefficients and flutter derivatives compared with the well-known experimental measurement and analytical formulation. Then, extended airfoil flow simulations were carried out to examine the potentially significant effects on aeroelasticity from several influencing factors, including non-zero equilibrium angles of attack, increased forced vibration amplitudes and large Reynolds number. Both the basic and extended simulations reveal that using the proposed CFD method can provide effective assessment of aerodynamic and aeroelastic performance of airfoils even for operating conditions beyond those a laboratory test can approach, indicating the possibility of extending the methodology proposed for realistic aerodynamic and aeroelastic prediction of 3D full-scale aircraft structures.