FAST馈源舱结构气动力特性及耦联系统风振响应研究

RESEARCH ON THE AERODYNAMIC CHARACTERISTICS OF FAST FEED CABIN STRUCTURE AND THE WIND-INDUCED RESPONSES OF THE COUPLED SYSTEM

  • 摘要: 500 m口径球面射电望远镜的馈源舱工作在140 m高空,对风荷载敏感,过大风振响应可能影响馈源舱的正常工作。该文利用CFD数值模拟方法研究了馈源舱结构的气动力特性,确定了表面凸起部分对馈源舱结构气动力特性有极大影响,并发现240°风向是气动力系数最大的风向,180°为潜在涡激振动的风向,进而针对180°风向进行参数分析,计算了不同风速下的旋涡脱落频率和斯托罗函数。随后建立了完整的馈源舱-索塔耦联体系精细化有限元模型,模态分析结果表明:该结构体系的基频很小,且模态密集;在常遇风速内可依次激发结构的多阶模态。针对气动力系数最大的240°风向进行风振响应分析,计算了馈源舱-索塔耦联体系在工作风速和设计风速下的动力响应,结果表明:馈源舱在工作风速下的位移不会影响其工作精度,且在设计风速下整体结构处于安全水平;在开启和关闭二次精调平台时,最大工作风速分别可以达到9.3 m/s、4.3 m/s。

     

    Abstract: The feed cabin of the five-hundred-meter aperture spherical radio telescope operates at an altitude of 140 meters, which is sensitive to wind load. Excessive wind-induced response may affect the normal operation of the feed cabin. The aerodynamic characteristics of the feed cabin structure are studied by CFD numerical simulation. The research results confirm that the surface bulge has a great influence on the aerodynamic characteristics of the feed cabin structure. According to the research results, the wind direction with the largest aerodynamic coefficient is 240 degree and the wind direction of potential vortex-induced vibration is 180 degree. Then the parametric analysis is presented for the 180 degree wind direction. The vortex shedding frequency and Strouhal number are calculated under different wind speeds. Besides, a complete refined simulation model of the feed cabin-cable-tower coupled system is established. The results of modal analysis show that the fundamental frequency of the structure is very low and the modes are dense. Multiple modes of the structure can be successively excited in normal wind speed. The wind response analysis is carried out for 240 degree wind direction with the largest aerodynamic coefficient. The dynamic responses of the feed cabin-cable-tower coupled system are calculated under the working wind speed and the design wind speed. The results show that the displacement of the feed cabin under the working wind speed will not affect its working accuracy, and the whole structure is in a safe level under the design wind speed. When the secondary fine-tuning platform is turned on and off, the maximum working wind speed can reach 9.3 m/s and 4.3 m/s, respectively.

     

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