Wind tunnel tests on in-line oscillation of a two-dimensional circular cylinder

Flow-induced in-line oscillation of a two-dimensional circular cylinder model was experimentally investigated in a wind tunnel by the free-oscillation method in order to understand some of the fundamental characteristics of the system. The response amplitude was measured over a wide range of the mass-damping parameter. The discussion is focused primarily on the effects of model aspect ratio and on the number of degrees of freedom of the dynamic system on the response amplitude. As a result of the tests, it was found that the response amplitude of a model with aspect ratio of 6.8 is larger than that of the model with aspect ratio of 1.8. It was also determined that in the region of reduced velocity corresponding to the 1st peak of in-line oscillation, the response amplitude of the model in one degree of freedom is larger than that of the model in two degrees of freedom.