Experimental study on the avoidance and suppression criteria for the vortex-induced vibration of a circular cylinder

Sakai, Takaaki; not registered ; not registered; not registered 

Experimental validation of the design method to prevent the failure of a thermometer well by the vortex-induced vibration has been performed for the effect of structure damping of a cylinder. The available experimental data in piping were very limited for the high damping region in water flow, because of the difficulty to increase the structure dumping for the one-side supported cylinder in experiments. ln this experiment, high viscosity fluid was charged into the tested cylinders to control the cylinder's damping. Resulting values of the reduced damping are 0.49, 0.96, 1.23, 1.98, 2.22 in the experiments. Reduced velocity(Vr) was increased gradually in the range of 0.7 Vr 5(Reynolds number at Vr=1 is 810). The displacements of the cylinder by the vortex-induced vibration were measured. As the results, Tested cylinders of reduced damping 0.49 and 0.96 showed vortex-induced vibration in flow direction at Vr 1 region. However, in case of reduced damping of 1.23, 1.98 and 2.22, the vortex-induced vibrations in flow direction were suppressed lower than the 1% displacement of the cylinder diameter. ln conclusion, it is confirmed that the suppression criteria of the "Vr 3.3 and Cn 1.2" for vortex-induced vibration in flow direction, which is used in ASME code; "Boiler and Pressure VesseI Code Sec.III Appendix N-1300" and the "FIV design guide in JNC", is reasonably applicable to the one-side supported cylinder in water flow piping.