2.16米望远镜圆顶通风技术研究

Dome venting is an essential part in dome design. It could promote the air circulation and improve the dome seeing. Adding a series of large openings, “vents”, in the skin of the dome is one of the effective methods. However, the patterns of the thermal equilibrium and wind loading affected by quantity and size of the vents are still to be solved. In the mean time, preliminary works show that primary baffle will influence the airflow above the primary mirror and decrease the accuracy, which has not been considered in previous research of dome venting. This project will research on dome venting technique, focused on the improvement of the dome seeing of 2.16-meter telescope. We will (1) analyze the dome seeing based on the measured data of temperature inside the dome; (2) utilize the computational fluid dynamics method to make the dome venting model and compare with the temperature data to validate the correctness of the model, to optimize the configuration of the vents by analyzing the relevance between the vents and the thermal equilibrium, wind loading, primary baffle turbulence; (3) analyze the effectiveness of combination of the dome vents and the exhaust fan, to visualize the venting airflow by applying the Schlieren imaging method. The results will provide theoretical bases and experimental data for 2.16-meter telescope and are significant for the dome design of the future large telescopes.

圆顶通风已成为天文望远镜圆顶设计中必不可少的部分，可有效促进圆顶内外的空气流通，改善圆顶视宁度。在圆顶外壁开通风孔是圆顶通风的有效方法之一，但通风孔数量、大小如何影响圆顶内外热平衡及望远镜风载问题仍需解决。前期工作表明主镜遮光筒会引起主镜表面空气湍流，影响观测精度，以往圆顶通风技术研究未考虑此因素。本项目针对2.16米望远镜的圆顶视宁度改善，开展圆顶通风技术研究：(1)实际测量圆顶内各处的温度变化，分析圆顶视宁度变化规律；(2)利用计算流体动力学方法建立望远镜圆顶通风模型并与实测温度数据对比，深入研究通风孔对圆顶内外热平衡、望远镜风载及主镜遮光筒引起湍流的影响，以优化圆顶通风孔配置；(3)分析圆顶通风孔与主动排风共同作用的效果，并采用纹影可视化技术，直观的“看到”到通风效果。本项目为2.16米望远镜圆顶通风改造提供理论基础和实验依据，对提高望远镜观测质量和未来大型望远镜圆顶设计有重要意义。

现代光学天文望远镜朝着大口径的方向发展，望远镜圆顶也随之增大，使得圆顶通风的问题尤为重要。圆顶通风可有效促进圆顶内外的空气流通，改善圆顶视宁度，从而提高望远镜观测精度。本项目针对2.16米望远镜圆顶视宁度改善，开展了圆顶通风技术研究。根据望远镜光机结构建立了2.16米望远镜和圆顶的三维模型。将实测的温度数据和风速数据作为圆顶通风模型的输入条件。根据2.16米望远镜圆顶的结构，设计了不同的通风孔配置并完成了通风效果的对比分析，得到多个小尺寸通风孔的效果优于少量大尺寸通风孔的结论。本项目也搭建了圆顶通风实验平台和纹影成像系统并完成了测试。研究了2.16米望远镜吊装通道改造为主动排风系统的通风效果。通过本项目研究，可为2.16米望远镜和其他望远镜圆顶通风改造提供实验依据，实现圆顶通风效果分析，对提高望远镜观测质量和未来大型望远镜圆顶设计有重要意义。

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