New approach to enclosure design for large telescopes

An enclosure design concept is proposed for a large ground-based optical telescope in the 20- to 30-metre class. The proposed configuration differs from the enclosures for existing large telescopes. Current large telescope enclosure designs have inherent inefficiencies which may be substantially magnified if these designs are scaled. Dynamic analysis studies show that motion requirements for the mechanical components of existing enclosures may be too stringent for next-generation enclosures and that these requirements should be revisited. The proposed enclosure design uses a spherical base structure with a rotating inclined cap. This design improves upon some of the mechanical, structural and operational inefficiencies of current spherical enclosures with conventional shutters. The design also offers potential advantages in the protection of the telescope from wind buffeting forces. Wind loading is expected to be one of the most significant factors governing the design of a next-generation large telescope. The enclosure design includes features which are expected to improve the air flow characteristics in and around the enclosure. Preliminary computational fluid dynamics (CFD) studies have been performed in order to analyze the effect of various enclosure details and components on the flow patterns. Future comparative and detailed CFD studies on the enclosure and telescope are proposed. A plan for practical validation of the results of CFD analysis is presented, in order to better understand the benefits of CFD in predicting the effects of wind buffeting on next-generation large telescopes.