Wind Proofing LIGO

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Abstract:: To reduce problematic wind that contributes to ground tilt, LIGO has proposed building a 50% porous fence around End Station X. We employed experimental and computational methods to evaluate the proposed fence. First, we measured different fence materials with a fan and a wind tunnel. Both the Tenax Wind Screen material and the Belton Industries material reduced wind speed by about 50%, so the main differences will arise from cost and material strength. Next, we employed Computational Fluid Dynamics (CFD) modeling to evaluate the wind load on End Station X with and without a porous fence. We found that the porous fence is quite effective in reducing the load on the building. Models show that with a fence, problematic wind speeds could be above 20 m/s, which only occur 1.54% of the time. We then evaluated data from the test fence at LIGO Hanford and compared these data to steady-state and transient CFD models. The Tenax test fence was found to reduce wind speed by 57%, while the steady-state CFD model showed 60% reduction. However, the transient model appears to show more variability than the real data in some areas, suggesting that the fence may smooth wind flow. A 50% porous fence is a well motivated wind proofing measure for End Station X, yet more robust model verification should be completed.

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LIGO Document G1801645-v3