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Journal of ZheJiang University (Engineering Science)  2020, Vol. 54 Issue (12): 2310-2320    DOI: 10.3785/j.issn.1008-973X.2020.12.005
    
Optimization and experiment of heliostat surface shape bracing structure based on plane truss
Song CHENG1(),Zong-feng ZOU2,*()
1. School of Mechatronic Engineering and Automation, Shanghai University, Shanghai 200444, China
2. School of Management, Shanghai University, Shanghai 200444, China
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Abstract  

A technical route of the optimization of heliostat surface bracing structure based on plane truss was proposed because of the complex influence factors of reflector forming. Four key points that included the surface width/height ratio of the 20 m2 heliostat, the cross-section moment of the upper chord, the optimization of the space between the plane truss groups and the quantification of control points in machining stage was analyzed, by simulation, numerical calculation and optimization algorithm. Trial-manufacture and field experiment was conducted that the distribution characteristics of spot sharp and energy flux were the same as that of ideal spherical shape, and their goodness of fit was greater than 0.98. The experimental results showed that when the surface width/height ratios set to 1.2, the cross-section moment of the upper chord set to 40 000 mm4, the truss groups spacing set to 950 mm, the tolerance of upper chord and inclined rod was less than 0.9 mm, and the reflective surface quality was improved. The feasibility of optimization technique route was proved by the principle and practice.



Key wordsheliostats      surface shape      plane truss      bonding mode      spot     
Received: 26 June 2019      Published: 31 December 2020
CLC:  TP 301  
Corresponding Authors: Zong-feng ZOU     E-mail: chengsong@shanghai-electric.com;zfzou@mail.shu.edu.cn
Cite this article:

Song CHENG,Zong-feng ZOU. Optimization and experiment of heliostat surface shape bracing structure based on plane truss. Journal of ZheJiang University (Engineering Science), 2020, 54(12): 2310-2320.

URL:

http://www.zjujournals.com/eng/10.3785/j.issn.1008-973X.2020.12.005     OR     http://www.zjujournals.com/eng/Y2020/V54/I12/2310


平面桁架构建的定日镜面形支撑结构优化及实验

针对反射面成型的复杂影响因素,提出平面桁架构建的定日镜面形支撑结构优化技术路线. 利用模拟仿真、数值计算和优化算法等方法,解析20 m2定日镜面形定义技术路线的4个组成环节:面形规格及宽高比、上弦杆的截面矩、平面桁架组间距的最优值、机加工中工艺控制要点的量化. 试制小型定日镜进行实验,分析光斑形状和能流密度分布特性,并与理想球面形光斑比较,两者的拟合优度大于0.98. 实验结果表明,当反射镜宽高比取1.2,上弦杆截面矩取40 000 mm4,桁架组间距取950 mm,上弦杆和斜杆的开孔公差小于0.9 mm时,反射面形的质量提升. 研究从原理和实践上证明了该优化技术路线的可行性.


关键词: 定日镜,  面形,  平面桁架,  粘接方式,  光斑 
Fig.1 Map of typical position of heliostat field
编号 x y z
1 200 0 3
2 141 141 3
3 0 200 3
4 ?141 141 3
5 ?200 0 3
6 ?141 ?141 3
7 0 ?200 3
8 141 ?141 3
9 1 200 0 0
10 849 849 3
11 0 1 200 3
12 ?849 849 3
13 ?1 200 0 3
14 ?849 ?849 3
15 0 ?1 200 3
16 849 ?849 3
Tab.1 Heliostat coordinate table
Fig.2 Curve of aspect ratio of heliostat and spot size
Fig.3 Curve of heliostat ratio and average optical efficiency
Fig.4 Whole machine diagram
Fig.5 Force diagram of upper chord
材料 E/Pa μ ρm /(kg·m?3
200×109 0.30 7 800
反射镜 7×1010 0.20 2 500
双面胶带 60 000 0.49 710
Tab.2 List of material parameters of heliostat bracing structure
Fig.6 Flow chart of section parameter optimization algorithm
Fig.7 Error curve between section moment and deflection
Fig.8 Upper chord section
Fig.9 Standard error under different layouts
Fig.10 Standard error for different pitch angle
Fig.11 Supporting diagram of mirror thin plate
Fig.12 Comparison chart of central stress of mirror between two kinds of ways
Fig.13 Bending alignment error of upper chord with hinge hole
Fig.14 Curve of hole position deviation and surface profile standard error
Fig.15 Technical route of surface bracing structure design
宽/mm 高/mm 面形
半径/m
弦杆
材料
上弦杆截
面矩/mm4
上弦杆
间距/mm
双面
胶宽/mm
800 1 400 74 铝型材 3 000 380 20
Tab.3 Main parameters of trial-manufacture heliostat
Fig.16 Heliostat and its graph of surface standard error
地理位置 时间 距离 朗伯靶方位 朗伯靶尺寸
北纬31.25东经121.47 2019-03-15 37 m 正南高4 m 1.5 m×1.5 m
Tab.4 Filed experimental conditions
Fig.17 Distribution diagram of PillBox model
Fig.18 Diagram of slope error of mirror
Fig.19 Spot contrast between experiment and simulation mode
Fig.20 Energy ratio of simulated and experimental spots along radial direction
Fig.21 Flux density of simulated and experimental spots along uv direction
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