| Square cylinders have a wide range of applications in practical projects,such as high-rise buildings,piers and pylons.Due to the small spacing,there is a phenomenon of aerodynamic interference between the two coaxial square cylinders,and the wind pressure distribution,aerodynamic force and vortex shedding characteristics are significantly different from those of the single square cylinder.At present,the research on the two coaxial square cylinders is often only for the tandem and parallel states,and the research on the oblique state is less,and the interference effect of the aerodynamic characteristics has not been studied clearly.In view of this,a new device has been designed and developed for studying the aerodynamic characteristics of the two coaxial square cylinders in this paper.The aerodynamic characteristics of the two coaxial square cylinders have been studied by using this device.The main work of this paper is as follows:?1?A new device for studying the aerodynamic characteristics of the two coaxial square cylinders was designed and developed.This device not only can easily adjust the spacing between the two coaxial square cylinders,but also can easily change the wind direction angle,which greatly improves the test efficiency.?2?Using the developed new device,the aerodynamic characteristics of the two coaxial square cylinders at 14 different intervals between the range of 0°90°wind direction is studied.The results show that the critical spacing is closely related to the wind direction angle.Among them,the critical spacing at 0°and 5°wind direction angle is 3??L/D?cr?3.5;the critical spacing at 10°wind direction angle is3.5??L/D?cr?4;the critical spacing at 80°and 85°wind direction angle is 2??L/D?cr?3;the critical spacing at 90°wind direction angle is 1.8??L/D?cr?2.5;the critical spacing within the 15°75°wind direction angle is not obvious.?3?The time average wind pressure coefficient and the fluctuating wind pressure coefficient of the single square cylinder and the two square cylinders arranged in a line are compared and analyzed,and the interference effect of the wind pressure distribution of the upstream and downstream square cylinder is revealed when the wind direction angle and spacing are different.?4?The time average drag coefficient,time average lift coefficient and the fluctuating lift coefficient of single square cylinder and the two square cylinders arranged in a line are compared and analyzed,and the interference effect of upstream and downstream square cylinder aerodynamic forces is revealed when different wind direction angles and spacings are obtained.?5?The strouhal number of the single square cylinder and the two coaxial square cylinders had been contrasted and analyzed,revealing the interference effect of the vortex shedding characteristics of the upstream and downstream square cylinders at different wind direction angles and spacings. |
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