Numerical simulation of ground-based telescope enclosures

Abstract

In order to choose enclosure for the next generation telescopes, numerical simulation method was used. Firstly, the telescope, two general kinds of enclosures structure and the external flow field model were established, Then CFD(Computational Fluid Dynamics) technology was used to analyze the wind speed, static pressure, turbulence kinetic energy distribution and eddy around the telescope, when the telescope at two different pointing gestures and the external wind speed at 10m/s. The simulation results showed that when the telescope adapt the retractable enclosure, the wind speed of the main optical path between 6.1 m/s and 9.3 m/s, and the average static pressure (gauge pressure) on the primary mirror between 42.9268 Pa and 37.5579 Pa, however when telescope adapt the hemispherical enclosure, the wind speed of the main optical path between 3.4 m/s and 6.8 m/s, the average static pressure (gauge pressure) on the primary mirror between 12.1387 Pa and 11.105 Pa. Although the wind resistance of the retractable enclosure was lower than the hemispherical enclosure, no eddy generated near the main optical path, it provided the telescope a uniform flow field and ensured the quality of the image of a star. So the retractable enclosure would have better performance than the hemispherical enclosure.