Wind-Induced Dynamic Responses of Structures with Outrigger Systems
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Determination of the Strouhal number based on the aerodynamic behavior of rectangular cylinders
The Strouhal number is an important nondimensional number which is explanatory of aerodynamic instability phenomena. It takes on the different characteristic constant value depending upon the cross-sectional shape of the body being enveloped by the flow. A number of investigations into this subject, especially on the drag test, surface pressure test and hot-wire test, have been carried out under the fixed state of the body in the past. However, almost no investigations concerning the determination of the St on wind-induced vibration of the body have been reported in the past even though the aerodynamic behavior of the body is very important because the construction of wind-sensitive structures is recently on the sharp increase. Based on a series of wind tunnel tests, this paper addresses a new method to determine the Strouhal number of rectangular cylinder in the uniform flow. The central idea of the proposed method is that the Strouhal number can be obtained directly by the aerodynamic behaviors of the body through wind-induced vibration test. The validity of proposed method is evaluated by comparing with the results obtained by previous studies in three B/Ds at attack angle and a square cylinder with various attack angles. The values and trends of the proposed Strouhal numbers are in good agreements with values of previous studies. And also, the Strouhal numbers of B/D
Frequency selective surface design for blinds applications
In this paper, the reconfigurable blind structure with frequency selective surfaces(FSS) for the building applications are presented. Frequency transmission characteristics for different angles of the proposed blind-FSSs are investigated and verified through simulation and measurement. The simulation results show that we can implement the reconfigurable blind-FSS for multiband wireless applications. To verify the proposed paper, two kinds of blind-FSSs, crossed dipole FSS and circular ring FSS are fabricated and measurements are performed for different angles. The proposed structure in this paper which is very simple, can be easily applied to any planar surface for wireless security applications at low cost.