Investigations of aerodynamic effects on streamlined box girder using two-dimensional actively-controlled oncoming flow

The aerodynamic behavior of a streamlined box section model is characterized in an actively controlled wind tunnel with multiple fans and vibrating airfoils in Miyazaki University, Japan. A series of single pseudo harmonic fluctuating wind flows with discrete frequencies are generated. The aerodynamic admittance components obtained via a cross-spectral identification method for different incoming flows present obvious deviations between each other. This indicates the probable dependence of aerodynamic admittance on the characteristics of oncoming flow, which implies the limitation of conventional buffeting theory. More attention is focused on the relationship between aerodynamic forces and wind turbulence components, along- and across-wind cross-wind, in pseudo sinusoidal flow conditions. It is found that the across-wind turbulence has dominant influences on lift and pitching moment forces. With the strengthening of along-wind turbulence, the lift force increases, while the drag and pitching moment forces vary with different trends in different frequency ranges. Moreover, the contribution of along-wind turbulence to lift and pitching moment forces is considered to be negligible compared with that of the cross-wind turbulence, while for the drag force, the two turbulence components present comparative contributions.