GMT enclosure wind and thermal study

Arash Farahani; Alexy Kolesnikov; Leighton Cochran; Charles Hull; Matt Johns

doi:10.1117/12.924334

17 September 2012 GMT enclosure wind and thermal study

Arash Farahani, Alexy Kolesnikov, Leighton Cochran, Charles Hull, Matt Johns

Proceedings Volume 8444, Ground-based and Airborne Telescopes IV; 84440U (2012) https://doi.org/10.1117/12.924334
Event: SPIE Astronomical Telescopes + Instrumentation, 2012, Amsterdam, Netherlands

Abstract

The GMT (Giant Magellan Telescope) is a large ground-based telescope for astronomical research at optical and infrared wavelengths. The telescope is enclosed inside an Enclosure that rotates to follow the tracking of the telescope. The Enclosure is equipped with adjustable shutters and vents to provide maximum ventilation for thermal control while protecting the telescope from high wind loads, stray light, and severe weather conditions. The project will be built at Las Campanas Observatory in Chile on Cerro Las Campanas. The first part of this paper presents the wind tunnel test data as well as CFD (Computational Fluid Dynamics) study results for the GMT Enclosure. The wind tunnel tests include simulations for: a) Topography, b) Open Enclosure (all the shutters and vents open), and c) Closed Enclosure (all the vents and shutters closed). The CFD modeling was carried out for a wide range of conditions such as low and high wind speeds at various wind directions, and for the fully open and partially open Enclosure. The second part of this paper concerns the thermal effects of the Enclosure steel members. The wind speed and member sizes have been studied in relation to the required time to reach a defined temperature inside the Enclosure. This is one of the key performance characteristics of the Enclosure that can affect "Dome Seeing" significantly. The experimental data and theoretical predications have been used to identify the areas inside the Enclosure that need to be ventilated. The Enclosure thermal control strategy has been determined and an optimized system has been designed based on the final results.

Citation Download Citation

Arash Farahani, Alexy Kolesnikov, Leighton Cochran, Charles Hull, and Matt Johns "GMT enclosure wind and thermal study", Proc. SPIE 8444, Ground-based and Airborne Telescopes IV, 84440U (17 September 2012); https://doi.org/10.1117/12.924334

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