【作者】 刘岩；

【导师】 范峰； 钱宏亮；

【作者基本信息】 哈尔滨工业大学 ， 结构工程， 2013， 博士

【摘要】 中科院、国家发改委及新疆自治区将在奇台建造一口直径为110m的地面全可动射电望远镜。建成投入使用后，其口径将成为世界之最，性能将达到国际领先水平。然而建造如此超大跨度的望远镜，从结构技术角度最为突出的问题如下：传统结构方案存在若干不合理之处，仅自重作用就显著降低了主反射面精度（也称主反射面RMS），制约了其性能的发挥；同时迎风姿态多样造成主反射面风压分布复杂以及日照作用引起的非均匀温度场，均严重影响了主反射面RMS值；此外，电磁波在副反射面聚焦而产生的“太阳灶”效应也应引起重视。围绕上述关键科学问题，以控制主反射面RMS值为主线，提高主反射面精度为目标，本文拟从如下四方面展开研究：1、射电望远镜结构总体方案改进与优化以提高主反射面精度为目标，首先对全可动望远镜结构工作原理及反射面RMS拟合方法进行介绍；其次分析了传统结构方案精度较低的本质原因为：主反射面存在集中荷载作用、背架结构支承方案不合理、背架结构体系空间受力性能不佳。基于此，分别对其进行改进或创新，提出了一种新型高效的全可动望远镜结构总体方案，有效的提高了反射面精度。2、背架结构截面优化、几何参数分析与最佳安装角度的确定以主反射面精度为优化目标，引入遗传算法并进行改进，对背架结构进行截面优化，获得了一组较优的截面尺寸；在此基础上，对除截面尺寸以外的其它几何变量进行参数分析，探讨了它们对反射面RMS的影响程度。同时，仍以提高反射面精度为目标，利用梯度法的基本思想对望远镜背架结构的最佳安装角度进行了优化确定。3、反射面结构风荷载特性及其对精度的影响采用风洞试验和CFD数值模拟相结合的研究方案，对一类典型反射面（焦径比为0.3）结构展开各迎风姿态下的风荷载及风振响应特性分析，获得了适用于该类结构设计的风荷载取值。基于此，对既定的望远镜结构分别进行了生存风速和工作风速下的结构性能分析，评估了望远镜结构的力学可靠性，探讨了各类荷载对反射面RMS的影响，为后续反射面促动器的变形调控提供参考依据。4、日照非均匀温度场特性及其对反射面精度的影响以主、副反射面为研究对象，采用瞬态传热有限元分析方法，建立了综合考虑太阳辐射、空气对流换热、阴影遮挡等因素的望远镜整体结构日照温度场精细化数值模型。并选取最不利工况对其进行日照作用分析，获得了望远镜变位中该作用对主反射面RMS的全过程影响，以及电磁波聚焦在副反射面产生的“太阳灶”效应的时间及空间分布特性。更多还原

【Abstract】 Chinese Academy of Sciences, National Development and Reform Conmmissionand the Xinjiang Uygur Autonomous Region will unite together to construct a largeall-movable radio telescope which has an aperture of110m diameter in the county ofQitai. It will be the largest all-movable radio telescope on the groud to achieve the mostadvanced level in the world after it is put into use.Yet if such large radio telescope is built, the most prominent problems from thestructure techniques are listed as follows. There are several improper points in theconventional structure style. Only the gravity load seriously destroyes the reflectorsurface precision (which is called as RMS for short afterwards) and forbids itsperformance. Meanwhile, many kinds of upwind profiles cause complicated windpressure distribution to reflector surface. Moreover non-uniform temperaturedeformation caused by solar effect inevitably affects the suface RMS. Espesically solarcooker problem in the sencondary reflector because of the electromagnetic wavefocusing also should be paid attention to.Based on the scientific problems above, in order to control the surface RMS, thepaper will carry out the corresponding research work in the following four aspects.1. Improvement and optimization of the overall radio telescope structure schemeIn order to improve the main reflector surface RMS, firstly the working principleof the telescope and the surface precision fitting method are introduced. Then the natureof surface precision decline is analyzed and as follows：the main reflector hasconcentrated loads, the back frame support structure is not reasonable and back framestructure has a poor performance of stress. Based on these problems, a series ofimprovements and innovations are put into effect to the structure. Finally a newstructure scheme and several connections are put forward.2. Back frame structure optimization, geometric parameters analysis and the bestinstalled angle confirmationAdopting the main reflector surface RMS as the optimization object, the geneticalgorithm is introduced and improved to optimize the cross section of each bar for theback frame structure and a better set of cross section is acquired. On the basis of resultsabove, other parameters analysis is carried out to the back frame structure. And theinfluence on the surface RMS of these geometric variables is investigated. Afterward inorder to pursue the best precision, the gradient method is utilized to obtain the bestinstalled and adjusted angle of the back frame structure.3. Wind load characteristics of the reflector and its influence on the surface RMS Aiming at open parablolic reflector，wind tunnel and CFD adopted, a commonlyused type of reflector (F/D=0.3) is selected as research object to carry out the windtunnel test and numerical simulation for various kinds of upwind profiles. Its wind loaddistribution characteristics, wind vibration response characteristics and a huge mass ofwind resistance design data is obtained. Based on it, the mechanics performance and isanalyzed respectively at the survival wind speed and working speed to the establishedstructure. The analysis results assess the reliability of its mechanics performance,discuss the different effect on surface RMS of several kinds of loads and provide thevaluable references for deformation control of the actuators in the future.4. Sunshine non-uniform temperature field charateristics and its influence on thesurface RMSAdopting the main and secondary reflector structure as the analysis objects, thefinite element model of the all-movable telescope for structural temperature fieldanalysis is established, with the factors of solar radiation, shadow in surroundingenvironment, periodic air temperature and etc taken into consideration at the same time.The worst-case weather condition is selected to make the solar effect for them. Themain reflector surface RMS by the time course is acquired during the change of pitchand azimuth angle. At the same time the solar oven effect combined the time and spatialdistributions in the secondary reflector is presented.更多还原