Vortex Induced Vibrations of a Square Cylinder in a Wind Tunnel

Abstract : An experimental study of the vortex-induced vibrations of a rigid square cylinder, mounted flexibly, in a wind tunnel is presented. Special attention is paid to keep the structural damping as low as possible. Structural supports are assumed to behave linearly through out the amplitude envelope. Experimental data comprises of amplitude curves and transient slopes. The experimental procedure was repeated to study the cylinder behaviour both under the memory effect and without it. The classical mode switch can be pointed out in both the cases. Hysteresis is however found only in the former case. Measurements consist of the time histories of oscillations using laser displacement sensors. Structural parameters are estimated without airflow. Time evolution of energy of the square cylinder is recorded and later manipulated to calculate the growth rate of oscillation amplitude in the transient regime.