Modeling of conventional flaps at high deflection-rate

We extend our experiments on a 50%-chord simple trailing edge flap in a NACA0006 airfoil, spanning the test section of a water tunnel, to examine analytical/phenomenological models for lift coefficient for periodic (as opposed to transient) flap-motion. The flap is actuated with a suite of electric linear motors, with period as low as 0.2 convective times. The main element of the wing is kept at 0 □ incidence, while the flap’s motions span a parameter-study of initial and final incidence. We extend the Goman-Khrabrov ordinary different equation for an “internal state” derived from static data, separately for the main-element of the wing, and the flap. This is facilitated by mounting in each wing-element its own force-balance. The ODE’s results are augmented with an added-mass calculation from traditional panel methods, and a parameter-output model to account for super-circulation from entrainment of the flow on the wing’s suction-side, at the higher flap deflection rates. This is compared with similar augmentation of Theodorsen’s attached-flow model.