Experimentally Investigation on the Vortex-Induced Vibration of Circular Cylinders: Effect of end conditions on the response of the Structure

In recent decades, experimental studies of the vortex-induced vibration (VIV) became one of the interesting fields of science. However, variety of assumptions and methods of experiments have led to different results in various researches. Several parameters such as mass ratio, aspect ratio, degrees of freedom, and boundary conditions affect the VIV response of a simple circular cylinder. The current paper reports and discusses the results of in-water VIV experiments on an elastically mounted rigid cylinder with various types of end conditions. This paper focusses on the effects of the end condition by attaching an endplate to a circular cylinder and the results compared with those from a cylinder with no endplate. The Reynolds number ranges from 5.8×103 to 6.6×104. Experimental setup have also been compared and verified with some classical results of VIV. Results of current study was favorably compatible with previous researchers’ results.
The experimental results show that, the end condition noticeably changes the VIV amplitude especially in the lock-in area. Moreover, non-dimensional amplitudes shift to the higher reduced velocities when the endplate is removed. In the frequency responses, the cylinder with no endplate has lower quantities rather than the cylinder with an attached endplate. Evaluation of lift force coefficients also shows a similar pattern of effects on the non-dimensional amplitude. Consequently, the excitation of the structure in the lock-in region increases, when the endplate from the cylinder’s end is removed.