Implementation of a Forth-Order Aeroelastic Coupling into a Viscous-Inviscid Flow Solver with Experimental Validation (for One Degree of Freedom)

The viscous-inviscid flow solver Q$^3$UIC for 2D aerodynamics has recently been developed at the Technical University of Denmark [1]. The Q$^3$UIC solver takes viscous and unsteady effects into account by coupling an unsteady inviscid panel method with the integral boundary layer equations by means of a strong coupling between the viscous and inviscid parts, and in this respect differs from other classic panel codes e.g. Xfoil. In the current work a Runge-Kutta-Nystr\"{o}m scheme was employed to couple inertial, elastic and aerodynamical forces and moments calculated by Q$^3$UIC for a two-dimensional blade section in the time-domain. Numerical simulations are validated by a three step experimental verification process carried out in the low-turbulence wind tunnel at DTU. First, a comparison against steady experiments for a NACA 64418 profile and a flexible trailing edge flap is presented for different fixed flap angles, and second, the measured aerodynamic characteristics considering prescribed motion of the airfoil with a moving flap are compared to the Q$^3$UIC predictions. Finally, an aeroelastic experiment for one degree of freedom --airfoil pitching- is used to evaluate the accuracy of aeroelastic coupling. \\[4pt] [1] A strong viscous--inviscid interaction model for rotating airfoils.~Ramos-Garc\'{\i}a, N\'{e}stor; S{\o}rensen, Jens N{\o}rk{\ae}r; Shen, Wen Zhong. Wind Energy, 2013.