Numerical Investigation of a Spoiler Effect on the Transonic Flutter Boundary

In this paper, the effect of a statically deflected spoiler on the transonic flutter boundary is investigated by means of numerical airfoil models. For this purpose, a spoiler geometry is added to the NACA64A010 airfoil and a wing cross-section of the NASA’s Common Research Model. The deflection angle and the hinge-line position of the spoiler are varied. Unsteady aerodynamic loads are obtained with a linearized CFD method in the frequency domain. The flutter results show an increase in flutter velocity in the transonic dip region due to the spoiler deflection, which seems to be connected to a change of the aerodynamic loading of the airfoil. However, deterioration in the flutter stability boundary can be found for some specific spoiler deflection angles, especially at high Mach numbers. A careful use of the spoiler and a dedicated scheduling scheme dependent on the Mach number are therefore suggested if the spoiler effect is exploited as part of future flutter suppression technologies.