An experimental study on galloping of a square prism with a splitter pate through lift response

摘要

To elucidate the aerodynamic mechanism of galloping, the authors attempt another approach in the time domain relative to this oscillatory instability. As a test body, the present study takes up a square-section prism with a stationary longsplitter plate in its wake. A black-box theory of galloping is presented. Wind-tunnel experiments are reported on the indicial pressure responses together with flow visualizations. The corresponding Reynolds numbers were approximately 1.9×10{sup}4 and8.9×10{sup}3, respectively. In addition to the measurement of the indicial pressure responses, the sinusoidal pressure responses are also measured by forcedly oscillating the same model. As a result, the indicial body motion produces theseparation-induced vortices on two sides parallel to the uniform flow, and these vortices are responsible for the lift force related to the onset of galloping. The quantitative agreement between theory and experiment is reasonable for slowly oscillatinggalloping.