Experimental Investigations On Active Flow Control Of The Wind Load On High-rise Building

:Due to the wide application of new high-strength lightweight materials, modern high-rise buildings become higher and higher, but their stiffness and damping ratio is getting smaller, they become more sensitive to the wind. Appropriate local flow control measures have been shown to significantly enhance the wind resistance of high-rise buildings. Based on wind tunnel test, aerodynamics and wake characteristics of a typical high-rise building model are investigated, on this basis, local steady suction and blowing methods are implemented. Several main results obtained are as follows:(1) Under uniform flow conditions, the aerodynamics and wake characteristics of a square cross-section high-rise building model are systematically investigated, average drag, fluctuating lift, surface pressure characteristics, vortex shedding frequency and other parameters are obtained for the evaluation of the effect of active control. The investigations found that under the effects of free-end downwash flow, the near wake of the high-rise building model is highly three dimensional. Two typical statuses are observed in the aerodynamic forces on the model: first, the lift fluctuates in large amplitude occurs, corresponding to a higher drag; second, the lift fluctuates without distinct periodicity, corresponding to a lower drag. These two typical statuses occurred alternately.(2) Four control methods are implemented:suction control in the top of model, suction control in the two sides of model, blowing control in the back and suction control in the back, the control effect of the wake and aerodynamic of the model is studied. The investigations found that the first three methods can effectively weaken the wind load on high-rise building model, in typical conditions, the average drag coefficient of the model is reduced by5.4%、30.6%、5.4%, fluctuating lift coefficient is reduced by37.8%、22.4%、68.4%, but the last method plays the opposite effect.(3) By measuring the wake structure of the model under control conditions, the mechanism of each control method is revealed. The investigations found that:suction control in the top can significantly weaken the strength and size of the wake vortex when compared with the natural case; suction control in the two sides of the cylinder reduces the flow separation of the crosswind surface and promotes the flow reattachment, thus reduces the width of the wake; blowing control in the back weakens the interaction between the separated shear layer of the wake, contributing to a narrower wake width and an increase in the length of the recirculation zone.