The Study Of Unsteady Aerodynamics Of Freely Falling Plates

The aerodynamics of freely falling objects is one of the mostinteresting flow mechanics problems. The motions and wakes of freelyfalling plates were studies and it was found that the diverse motions ofthe plates exhibit a systematic dependence on three non-dimensionalparameters, i.e. the thickness-to-width ratio, the dimensionless moment ofinertia I, the Reynolds number Re.We investigate the aerodynamics of freely falling plates in aquasi-two-dimensional unsteady flow. Using particle image velocimetrytechnology，we have dropped a large number of plates, the relationbetween and Re along the boundary separating steady and unsteadyfalling of the plate was determined. In the range of50-180of Re, we getthe relation between Strouhal number and Re，and compare with cylinder.We quantify the trajectories experimentally using high-speed digital videoat sufficient resolution to determine the instantaneous plate accelerations and thus to deduce the instantaneous fluid forces.