Experimental Studies on Fluctuating Lift Force on a Single Circular Cylinder at High Reynolds Numbers

Vortex shedding vibration is one of the most important problems to consider in the design of circular cylindrical structures such as the thermowell, the thimble tube for the ICIS and the support columns in nuclear reactors. The objectives of this study are to investigate the vibration response of these structures due to cross flaw aver the range of the high Reynolds numbers, and to propose suggestions to guide future designs of these structures. Experimental studies on the fluctuating lift force which acts on a single circular cylinder for the Reynolds numbers from 3x104 to 3x106 were conducted in a MEI waterchannel test apparatus. The tests were carried out by using two types of models with different stiffness characteristics. One was a stationary model which was used to measure the fluctuating lift force and the Strouhal number. The other was an elastic model which wasused to investigate the vibration response. The results obtained using these two models were a lift coefficient of CL rms and a Strouhal number of st. These results were the same values which have previously been reported by many other investigators. The “locked-in” vibration observed with the elastic model for the critical Reynolds number range was the same phenomena found in the subcritical Reynolds number range.