Flow control of a circular cylinder by self-adaptive furry microfibers

Abstract

In the present study, two columns of self-adaptive furry microfibers (nylon wires) are placed near the separation points of a cylinder to manipulate the wake vortex shedding and improve its aerodynamics performances. The effect of extension length on the control efficiency of the self-adaptive nylon wires is experimentally investigated at a subcritical Reynolds number of Re = [Formula: see text]. The unsteady aerodynamic forces of the cylindrical model with and without control are estimated by the pressure distributions around the model surface, and the flow structures are visualized by the high-speed particle image velocimetry measurement system and the smoke-wire technique. The results demonstrate that the nylon wires can significantly suppress the fluctuating lift forces acting on the cylindrical model and modify the wake-flow dynamics. The instantaneous results show that the nylon wires can stretch the unsteady shear layer with both sides of the cylindrical model, thus increasing the vortex formation length and pushing the vortex structure further downstream. Furthermore, the nylon wires with an appropriate length are found to suppress completely the wake vortex shedding pattern of the von Kármán vortex street.