Experimental Research On Mechanism Of Suction Control On Flows Around Bluff Bodies

With the continuous development of social economy,super high-rise buildings are moving toward a new era of rapid development.With the increment of the height of super high-rise buildings,the structure will become more flexible,and thus more sensitive to wind loads.Therefore,for the wind-resistant design of super high-rise buildings,it is quite important to effectively reduce the wind loads so as to control the wind-induced responses of structure.By continuous suction control method,the wind loads on super high-rise buildings can be reduced effectively,and the wind-resistant performance of structure can be improved.In previous studies,the effects of suction control,together with some major control parameters,on the drag reduction were investigated by the researchers.However,the mechanism of suction control has never been comprehensively studied.Moreover,in previous studies,f inite length models tend to be the major consideration for the suction control.However,due to the existence of numerous disturbance,including the heterogeneity of boundary-layer flow,the three-dimensional effect of flows around bluff bodies and spatial heterogeneity of suction slots arrangement,these studies cannot provide a deep insight into the mechanism of suction control.Therefore,in order to study the mechanism of flows around bluff bodies and the characteristics of aerodynamic force under suction control,refined study should be applied to two-dimensional models.In this study,for the bluff body models with three different kinds of cross-sections,the mechanism of suction control is thoroughly analyzed based on PIV technique.Then,the accuracy of CFD numerical simulation is validated through the comparison with the results obtained by wind tunnel test.The main contents in this paper are given as follows:1.In order to realize uniform suction control,the internal suction pipelines of test models are improved.Besides,eight b luff body test models with three different kinds of sections,including square,circular and ellipse,are designed.And then,the program of wind tunnel test is completed.Based on LES method,for the bluff body with a circular section,the CFD numerical simulation method of suction control is established.Moreover,the grid dependence and validation of the method are also performed in this pap er.2.The pressure measurement and PIV measurement of the bluff bodies with three different cross-sections are accomplished.And then,for these models,the effects of suction slot position and suction flow coefficient on the distribution of wind pressure,the aerodynamic coefficients of test models and the characteristics of flow field around test models are studied.Moreover,based on the visualization of flow field obtained by PIV wind tunnel test,the mechanism of suction control is analyzed deeply.3.For the typical model with a circular section,the quasi-two-dimensional CFD simulation is carried out.And the accuracy of the numerical simulation is evaluated through the comparison with the results obtained by the wind tunnel test.Moreover,for the cylinder models,the effects of suction flow coefficient and suction slot width on the results of suction control are studied from three aspects,including the wind pressure distribution,the aerodynamic coefficients and the characteristics of flow field around test models.