Transient Fluid Force on an Impulsively Rotated Circular Cylinder in a Uniform Flow

Experiments were carried out to study the transient lift produced on a circular cylinder, which started to rotate impulsively about its axis in a uniform flow. Since the lift was influenced by the strength and position of the shedding vortex, special care was taken to select the initial condition of rotation which is expressed by the lift coefficient and its derivative at t=0. Tests were performed for various acceleration rates of rotation and final rotational speeds in two representative initial conditions. As a result of this study, it has become clear that the higher acceleration results in a bigger shift of the transient lift from the steady state characteristics.