The flow development and force generation of a two-dimensional flat plate undergoing a pitch ramp-hold-return motion are reported. Direct force measurements and PIV flow field measurements are described. The experiments were conducted in water at a Reynolds number based on free stream speed and chord of approximately 5,000 and reduced frequency k = 0.2, where the reduced frequency is based on the rate of change of the pitch angle normalized with chord and free stream speed. The maximum pitch angle and the duration of the hold part of the motion were varied and their impact on the force generation and flow evolution were measured. As expected the force and flow evolution during the pitch ramp part of the motion is independent of the hold and return parts and is in agreement with previous work reported in the literature. It is found that the evolution of aerodynamic parameters during the hold part is a function of time and maximum pitch angle but independent of hold duration. However the force and flow evolution during the return part depends on the hold duration and maximum pitch angle. PIV measurements are used to document the evolution of the LEV and TEV vortices.

No abstract