地基望远镜风载数值分析

Numerical analysis of wind load on ground-based telescope

风载是影响地基望远镜性能的主要因素之一,为了研究风载荷的作用以及对望远镜性能的影响程度,首先建立了望远镜、圆顶和流场的几何模型。然后利用CFD(Computational Fluid Dynamics)分析了在外界风速为10 m/s的情况下,3种不同高角(30°、60°、120°)流场中截面空气速度、压力、湍流动能以及主镜面的静压力的瞬态分布,最后通过有限元方法获得了主镜去除刚体位移后的面形。仿真结果表明,望远镜以不同高角观测时主镜面静压力功率谱密度与Gemini望远镜的实测结果接近,真实模拟了风载荷的作用。由风载引起的镜面变形RMS值分别为3.74E-1 nm,2.5E-2 nm,1.71E-1 nm,满足面形精度要求。

Wind load is one of the main factors that affects the performance of ground- based telescopes, in order to investigate the function of wind load and the influence degree on the telescope, firstly, the telescope, dome, and exterior flow field geometry were established. Secondly, Computational Fluid Dynamics （CFD） was used to analyze the instantaneous distribution of the air＇s velocity, pressure and static pressure on primary mirror, at three different altitude angular（30°, 60°, 120°）, when the wind at the speed of 10 m/s. Finally, the primary mirror surface accuracy was gotten after removed the rigid body displacement through the finite element method. The simulation results show that static pressure power spectral density of the primary mirror is close to the measured data of Gemini telescope, better simulate the practical effect of the wind load. The RMS values of the mirror surface deformation caused by wind load are 3.74E- 1 nm, 2.5E- 2 nm, 1.71E- 1 nm meet the surface accuracy requirement.