CROSS-FLOW VIBRATIONS OF CYLINDER IN IRREGULAR OSCILLATORY FLOW

This study presents the results of an experimental work with a spring- supported cylinder exposed to irregular oscillatory flow. The steady c urrent and regular-oscillatory-flow cases are also included for refere nce purpose. The oscillatory-flow conditions are created by the so-cal led carriage technique. The cross-flow response of the cylinder has be en investigated for the Keulegan-Carpenter numbers equal to 10, 20, an d 36, and for the reduced velocity from 0 to 11.5. The effect of the w idth of the flow-velocity spectrum on the cylinder response was studie d. The results show that the cylinder vibrations under irregular-oscil latory-flow conditions differ considerably from the response in the re gular oscillatory flow. First of all, the cylinder responds mostly wit h its natural frequency. Second, vibration amplitudes are considerably reduced. Third, the vibrations are initiated earlier (i.e., at smalle r values of the reduced velocity) than in regular oscillatory flow.