Behavior of a horizontal air curtain subjected to a vertical pressure gradient

James Linden; LeEllen Phelps

doi:10.1117/12.925498

17 September 2012 Behavior of a horizontal air curtain subjected to a vertical pressure gradient

James Linden, LeEllen Phelps

Proceedings Volume 8444, Ground-based and Airborne Telescopes IV; 84443S (2012) https://doi.org/10.1117/12.925498
Event: SPIE Astronomical Telescopes + Instrumentation, 2012, Amsterdam, Netherlands

Abstract

We present the details on an experiment to investigate the behavior of an air curtain that is subjected to a transverse pressure gradient. The setup simulates the conditions that will be present in the Advanced Technology Solar Telescope (ATST), a 4-meter solar observatory that will be built on Haleakala, Hawaii. A test rig was built to replicate the region at which the optical path crosses a temperature and pressure boundary between the telescope mount region, which is at the ambient temperature and pressure, and a warmer, pressurized lab space directly below. Use of an air curtain in place of an optically-transmitting window at the interface would allow science observations at a wider range of scientific wavelengths. With the air curtain exhibiting transitional flow behavior across the boundary, and applied pressure gradients of up to 6.5 Pa, we found that the air curtain was able to hold a pressure gradient of 0.25 Pa. As the applied pressure was increased, transient turbulent regions formed at the interface, and predictable flow behavior only occurred in the region closest to the air curtain blower. Computer modeling is used to validate the test data, identify laminar regions of the air curtain where minimal image distortion would occur, and explore the relationship between the applied pressure, effective pressure difference, and air curtain profile.

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James Linden and LeEllen Phelps "Behavior of a horizontal air curtain subjected to a vertical pressure gradient", Proc. SPIE 8444, Ground-based and Airborne Telescopes IV, 84443S (17 September 2012); https://doi.org/10.1117/12.925498

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KEYWORDS

Curtains

Protactinium

Adaptive optics

Telescopes

Fluctuations and noise

Observatories

Space telescopes

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