Numerical study on crosswind stability of spherical structures. Issue 1 (July 2021) - Zhou, Yu
Abstract: Karman Vortex Street will be formed when steady incoming flow flows around square cylinder under a certain Reynolds number. The alternate shedding of Karman Vortex Street will affect the structure of the object which will cause structural vibration, and may even cause structural damage in severe cases. The "world's largest artificial moon" located in Hongguo, Panzhou City, Guizhou Province was selected as the research object in this paper, the flow around characteristics under different crosswind velocity of which are numerically studied by computational fluid dynamics, and then the crosswind stability of the structure is analyzed. Results shows that the vortex shedding mainly occurs in the cylindrical structure, while there is no obvious vortex shedding in the spherical structure and the natural frequency of the artificial moon is much higher than the vortex shedding frequency. There are 3 low-speed regions at different heights on the central section. The lowest velocity appears at the lower part of the leeward side of the spherical structure, and there is even a backflow phenomenon, resultsing in a local vortex. Under the same Reynolds number, Karman vortex street is more likely to appear in cylindrical structure than in spherical structure. In addition, as the Reynolds number increases from 8.1×10 5 to 1.6×10 7, except to the increase in overall wind velocity, the characteristics of flow around structure at the rear of the building change little under steady-state condition. The natural frequency of the artificial moon is much higher than the vortex shedding frequency. It means that the crosswind stability of the artificial moon investigated is satisfactory.