Plunge Instability of a Square Bluff Body in Crossflow

Flow-induced vibration tests were performed on a beam with a square cross section. The test article was induced into a plunge mode self-excited vibration by forcing air across the beam while it was suspended by leaf springs. The natural frequency and the damping were varied during these tests to alter the variables that contribute the onset of flow-induced vibration. Additionally, cantilevered beams were tested in the same wind tunnel and results proved to be consistent with results from the leaf spring supported beam. The slope of the vertical force coefficient was determined from this testing; this coefficient was determined to be approximately unity, which was roughly 1/3 of the value found in other published data.