Aerodynamic Forces on a Bluff Cylinder in Sinusoidal Streamwise Winds with Different Angles of Attack

Abstract

In the present study, multiple-fan active control wind tunnel tests are conducted to investigate the aerodynamic forces on a 5:1 rectangular cylinder in sinusoidal streamwise winds with different angles of attack (AoA). The effects of the frequency, amplitude, and AoA of the sinusoidal flow on the statistical parameters, spectral characteristics, and spanwise distributions of drag, lift, and moment coefficients are analyzed. Results show that each force has two components: the one induced by the approaching velocity oscillation and the one induced by wake vortex-shedding—this is quite different from that in the smooth flows, where the fluctuating forces are totally due to wake vortex-shedding. For each force, changes of the two components and their relationship with the frequency, amplitude, and AoA are presented. The drag fluctuations are generally dominated by the approaching velocity oscillations, whereas the lift and moment are more sensitive to wake vortex-shedding. Therefore, the drag force has better spanwise correlations than the lift and moment forces. Meanwhile, at a non-zero AoA, the inflow amplitude has different effects on the vortex-shedding-induced component as that at a zero AoA. The differences of spanwise distributions between the sinusoidal flow cases and the smooth flow cases are analyzed.

Investigation of the aerodynamic characteristics of single-box girders with different aspect ratios

“…The optimization of the main girder of a bridge can effectively improve the aerodynamic performance of the bridge. For rectangular cross-section structures without wind nozzles, their aerodynamic characteristics and wake characteristics depend largely on the flow characteristics of the separated flow from the leading edge [1][2][3][4][5]. Usually, the aerodynamic characteristics of rectangular structures can be categorized into three states: complete separation, intermittent reattachment, and complete reattachment based on their width-to-height ratios 𝐵/𝐷, where 𝐵 and 𝐷 are the width and height of the rectangular section [6][7][8].…”