巨型射电望远镜风荷载特性的数值模拟研究

发布时间：2018-11-29 08:46

【摘要】：巨型全可动射电望远镜项目的建设问题，是当前我国射电天文学领域关注的热点之一。风荷载的作用会降低望远镜反射面的形状拟合精度，影响其观测性能。目前，国内外对于望远镜结构风荷载特性的研究还非常有限。本文基于CFD（计算流体力学）数值模拟方法研究望远镜结构的风荷载特性，对影响风荷载特性的因素进行了参数分析，并基于研究结果对65m口径望远镜在平均风荷载作用下的精度进行了求解。本文主要内容包括： 1.采用不同湍流模型对望远镜球形保护罩和1.5米口径抛物面天线结构的风场进行了数值模拟，并与规范方法和风洞试验结果进行了对比分析，最终确定了采用RSM（雷诺应力）模型对望远镜结构风场进行数值模拟的方案。 2.基于CFD数值模拟方法和RSM湍流模型，对口径110米、焦径比0.32的射电望远镜结构在B类地貌下的风场进行了数值模拟，研究了其风荷载特性（包括风力系数、平均风压分布以及局部极值风压作用），并考虑了俯仰角和风向角的影响。给出了望远镜结构分区平均风压系数和分区风荷载体型系数，以方便工程应用。最后基于流场绕流特性的分析，对望远镜结构最不利受力姿态进行了预测。 3.多因素、多水平的组织正交数值风洞试验，对影响望远镜结构风荷载特性的若干因素进行了参数分析。其中，几何参数-口径选取D=65m、D=90m、D=110m三种情况，几何参数-焦径比选取f/D=0.3、f/D=0.5两种情况；风环境参数选取B类地貌和C类地貌两种情况；工作参数-俯仰角选取0度、30度、60度、90度共四种情况，工作参数-风向角选取0度、30度、60度、90度、120度、150度、180度共七种情况；并就俯仰轴高度和风速（雷诺数）的影响进行了分析。明确了各影响因素的范围和大小，，并给出了风荷载特性的相关规律，为工程实际中有针对性的进行抗风设计提供了参考依据。 4.基于CFD数值模拟结果，对65m口径射电望远镜在风荷载作用下的最佳法向偏差和整体位移进行了计算求解，评估了风荷载作用对望远镜结构精度的影响。
[Abstract]:The construction of giant fully movable radio telescope is one of the hotspots in the field of radio astronomy in China. The effect of wind load will reduce the shape fitting accuracy of the reflector of the telescope and affect its observation performance. At present, the research on the wind load characteristics of telescope structures is very limited at home and abroad. In this paper, based on CFD (computational fluid dynamics) numerical simulation method, the wind load characteristics of telescope structures are studied, and the factors affecting the wind load characteristics are analyzed. Based on the research results, the accuracy of the 65m telescope under the action of average wind load is solved. The main contents of this paper are as follows: 1. Different turbulence models are used to simulate the wind field of the spherical protective cover and 1.5 m paraboloid antenna structure of the telescope, and the results are compared with those of the standard method and the wind tunnel test results. Finally, a numerical simulation scheme for wind field of telescope structure using RSM (Reynolds stress) model is proposed. 2. Based on the CFD numerical simulation method and the RSM turbulence model, the wind field of the radio telescope with a diameter of 110m and a focal diameter ratio of 0.32 is numerically simulated under the B geomorphology, and the wind load characteristics (including wind coefficient) are studied. The distribution of mean wind pressure and local extreme wind pressure) and the influence of pitch angle and wind direction angle are taken into account. The average wind pressure coefficient and the wind load shape coefficient of the telescope structure are given in order to facilitate the engineering application. Finally, based on the analysis of the flow characteristics around the flow field, the most unfavorable attitude of the telescope structure is predicted. 3. Several factors affecting the wind load characteristics of telescope structures are analyzed by multi-factor, multi-level tissue orthogonal numerical wind tunnel test. Among them, there are three kinds of cases: the geometric parameter and caliber are chosen, the geometric parameter and the focal diameter ratio are chosen, the geometric parameter and the focal diameter ratio are chosen, and the wind environment parameter is chosen as the type B geomorphology and the C type geomorphology, and the wind environment parameter is chosen in the following two cases: class B geomorphology and type C geomorphology. The working parameter-pitch angle is 0, 30, 60 and 90 degrees, and the working parameter-wind direction angle is 0, 30, 60, 90, 120, 150 and 180 degrees respectively, and the working parameter-wind direction angle is 0 degrees, 30 degrees, 60 degrees, 90 degrees, 120 degrees, 150 degrees and 180 degrees. The influence of pitch axis height and wind speed (Reynolds number) is analyzed. The range and magnitude of the influencing factors are defined, and the related laws of wind load characteristics are given, which provides a reference for the engineering practice to carry out the wind resistance design. 4. Based on the CFD numerical simulation results, the optimum normal deviation and global displacement of 65m radio telescope under wind load are calculated and solved, and the influence of wind load on the structure accuracy of the telescope is evaluated.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2012
【分类号】：TU312.1;P111.44

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