Flow visualization of four 8-m telescope-enclosure designs

Walter A. Siegmund; Woon-Yin Wong; Fred F. Forbes; Charles H. Comfort Jr.; Siriluk Limmongkol

doi:10.1117/12.19227

1 July 1990 Flow visualization of four 8-m telescope-enclosure designs

Walter A. Siegmund, Woon-Yin Wong, Fred F. Forbes, Charles H. Comfort Jr., Siriluk Limmongkol

Proceedings Volume 1236, Advanced Technology Optical Telescopes IV; (1990) https://doi.org/10.1117/12.19227
Event: SPIE Astronomical Telescopes and Instrumentation for the 21st Century, 1990, Tucson, AZ, United States

Abstract

The preservation of image quality is one of the most important design criteria for a telescope enclosure. Image quality is adversely affected by the presence of fluctuations of air temperature in the light path. In an ideal telescope enclosure, the air inside the telescope chamber is continually replaced by ambient air before it has the opportunity to be warmed or cooled by the surfaces of the telescope enclosure. In the present study, dye in a water tunnel is used to trace flow around and through four models of 8 m telescope enclosures. The models are constructed of transparent acrylic and are 1:172 scale. Flow attributes are compared for the four enclosure designs under consideration. The enclosure models are oriented at various angles with respect to the flow direction. Additionally, each design contains apertures in the exterior walls which can be opened to improve flushing and other flow characteristics. For the octagonal and rectangular designs, flushing of the telescope chamber through the open vents is good in all orientations. Flushing of the cylindrical concept, which has no vents in its side walls, is poor when the slit is oriented from 60 to 120 deg with respect to the flow direction. Flushing of the hemispherical enclosure is poor at angles larger than 60 deg. With the vents closed, flushing is poor for all designs, especially at angles greater than 60 deg.

Citation Download Citation

Walter A. Siegmund, Woon-Yin Wong, Fred F. Forbes, Charles H. Comfort Jr., and Siriluk Limmongkol "Flow visualization of four 8-m telescope-enclosure designs", Proc. SPIE 1236, Advanced Technology Optical Telescopes IV, (1 July 1990); https://doi.org/10.1117/12.19227

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