Vortex-Induced Vibration of a Cantilever Circular Cylinder in Super-Critical Reynolds Number Flow and Its Suppression by Structure Damping

抄録

Experimental validation of the design criteria for preventing the failure of a thermometer well by vortex-induced vibration is presented, clarifying the effects of Reynolds number and structure damping. An existing avoidance criterion for the vortex-induced vibration in the flow direction, which is given in terms of the reduced velocity V_r as V_r<1.0, has been developed based on the experimental data mainly in the sub-critical range. The applicability of this criterion in the super-critical range is examined in this paper based on the results of experiments performed in the Reynolds number region from 7.8×10⁴ up to 1.1×10⁶ at V_r=1.0. On the other hand, an existing suppression criterion of vortex-induced vibration in the flow direction is given in terms of the reduced damping C_n as C_n>1.2 (or 2.5) under the condition of V_r<3.3 in design guidelines. This criterion, however, has been proposed based on very limited available data The appropriateness of the suppression criterion is also examined in this paper based on the results of experiments in realistic thermometer well conditions, i.e. cantilever cylinders with varied structure damping in a pipe water flow. As a result, it becomes clear that V_r<1.0 is applicable in the super-critical range up to 1.1×10⁶ and that the criteria of V_r<3.3 and C_n>1.2 are reasonably applicable to a cantilever cylinder in a pipe water flow.