Characterization of Aerodynamic Forces on Wings in Plunge Maneuvers

We present experiments and simulations of plunging maneuvers of large amplitude, for velocity ratios of G=1 and 2, defined as the ratio between the peak plunge velocity and the freestream velocity. We explore the effect of the airfoil shape by considering a NACA 0012 wing and a flat plate. The experiments are performed with wings with aspect ratios of 4 and 4.86, whereas the simulations are performed using a model of an infinite-aspect-ratio wing. We report the time evolution of the force coefficients and flow visualizations. A good qualitative agreement is found between experiments and simulations, with small discrepancies in the maximum and minimum lift coefficients observed during the maneuvers and somewhat larger discrepancies during the postmaneuver phase. It is found that the airfoil shape has a small effect on the lift coefficient but a somewhat larger effect on the drag coefficient. We also perform a force decomposition analysis to relate vortical structures to the force on the wings, providing a quantitative measurement of the effect of the leading-edge vortex and trailing-edge vortex on the peak aerodynamic forces.