Wind loading of large telescopes

Myung K. Cho; Larry M. Stepp; George Z. Angeli; David R. Smith

doi:10.1117/12.458191

4 February 2003 Wind loading of large telescopes

Myung K. Cho, Larry M. Stepp, George Z. Angeli, David R. Smith

Proceedings Volume 4837, Large Ground-based Telescopes; (2003) https://doi.org/10.1117/12.458191
Event: Astronomical Telescopes and Instrumentation, 2002, Waikoloa, Hawai'i, United States

Abstract

Wind loading is a critical issue for large telescopes and will be even more problematic for proposed future giant telescopes. As the current-generation telescopes were being designed in the 1980s and 1990s, numerous studies were made to understand airflow through the enclosures and wind loading of the telescopes. Now that these telescopes are in operation, it is important to consider what can be learned from them to: (1) verify the assumptions and predictions of previous studies; (2) establish procedures to optimize telescope operation; and (3) guide the design of future extremely large telescopes. With these goals in mind, Gemini Observatory conducted a campaign during the integration of the southern Gemini telescope to simultaneously measure wind velocities inside and outside the enclosure and pressure variations on the (dummy) primary mirror. The data collected in this campaign have been analyzed and results are presented that address these three goals. This paper points out several results that are different from the assumptions of previous studies. It presents a rule of thumb for allowable wind speed around the Gemini primary mirror. Results are shown indicating that the average pressure pattern on the Gemini mirror is primarily produced by airflow around the telescope structure, but that much of the dynamic pressure variation at the mirror comes from turbulence generated by the enclosure. Also described is a strategy for developing realistic wind loading input for simulating the performance of an extremely large telescope, including the spatial and temporal variation of pressure on the primary mirror.

Citation Download Citation

Myung K. Cho, Larry M. Stepp, George Z. Angeli, and David R. Smith "Wind loading of large telescopes", Proc. SPIE 4837, Large Ground-based Telescopes, (4 February 2003); https://doi.org/10.1117/12.458191

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