Vortex induced vibration of an inclined finite-length square cylinder

This study investigated vortex-induced vibrations of a slender square-section cylinder inclined from the vertical direction by a series of angles experimentally. Both aeroelastic tests and pressure measurements were performed on the cylinder with forward inclinations (inclined to the upwind direction), a vertical attitude, and backward inclinations (inclined to the downwind direction) in a wind tunnel. The cylinder was kept stationary in the pressure measurement tests. The aeroelastic test results show that vortex-induced responses of the cylinder decrease considerably as increasing the forward inclination angle. By contrast, the effect of the backward inclination on the vortex-induced vibration varies. Not all the backward inclined cylinders exhibit crosswind responses smaller than those of the vertical cylinder does. The responses of the cylinder with a small backward inclination are significantly larger, whereas the cylinder with a large backward inclination exhibits lower responses than those of the vertical case. The variation in the vortex-induced vibration response with the inclination is explained by performing power spectral analyses on the pressure data on the side face over the cylinder span, which reveals local vortex shedding characteristics. The findings provide significant guidance to the wind-resistant design of an inclined slender structure.