Model of image degradation due to wind buffeting on an extremely large telescope

Padin, S.; Davison, Warren B.

doi:10.1364/ao.43.000592

Cited by 13 publications

(17 citation statements)

References 4 publications

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“…While the enclosure surrounding the telescope provides a significant reduction in wind speeds, the residual wind loads that result from large-scale flow structures and turbulence inside the enclosure may still lead to significant vibration. 1,2 Estimates of the wind loads are required early in the design process, influencing the design of the enclosure, telescope structure, and control system. The wind parameterization herein reflects our best current understanding of the wind environment inside a roughly hemispherical telescope enclosure, informed by three separate sources of data.…”

Section: Introductionmentioning

confidence: 99%

“…Although the crosssectional area of M2 is small compared to that of M1, the structure around the mirror is exposed to higher wind speeds, and thus the resulting forces are also a significant contributor to image degradation, 1 resulting in the motion of M2 and the deformation of M1 through structural coupling. Steady forces can be compensated by active control of the mirror surfaces.…”

Section: Introductionmentioning

confidence: 99%

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Wind loads on ground-based telescopes

et al. 2006

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One of the factors that can influence the performance of large optical telescopes is the vibration of the telescope structure due to unsteady wind inside the telescope enclosure. Estimating the resulting degradation in image quality has been difficult because of the relatively poor understanding of the flow characteristics. Significant progress has recently been made, informed by measurements in existing observatories, wind-tunnel tests, and computational fluid dynamic analyses. We combine the information from these sources to summarize the relevant wind characteristics and enable a model of the dynamic wind loads on a telescope structure within an enclosure. The amplitude, temporal spectrum, and spatial distribution of wind disturbances are defined as a function of relevant design parameters, providing a significant improvement in our understanding of an important design issue.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Wind loads on ground-based telescopes

et al. 2006

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“…12,13 Finally, computational fluid dynamics (CFD) [13][14][15] is an ideal design tool, and can take advantage of the experimental data for validation, so that CFD can be used with confidence in future design work. The parametric model of wind forces herein builds on earlier efforts 3,4 by incorporating new information from recent computational and wind tunnel studies. The structural model is not yet parameterized; future efforts will include some parameterization of the structural finite element model (FEM) node geometry by using an input file as was done with VLOT.…”

Section: -8mentioning

confidence: 99%

“…Several studies have analyzed the wind-induced buffeting of the telescope structure that results from turbulence inside the telescope enclosure [3][4][5] and concluded that this vibration must be taken into account in the design process, affecting the design of the telescope enclosure, the telescope structure and the active control system. Estimating the degradation in image quality that results from the wind-induced vibration requires understanding the wind inside the enclosure, coupling these forces to a structural model, estimating the achievable reduction in vibration using active control, and computing the optical consequences of the residual vibration.…”

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confidence: 99%

Parametric modeling and control of telescope wind-induced vibration

et al. 2004

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A parametric model of the dynamic performance of an optical telescope due to wind-buffeting is presented. The model is being developed to support the design of next generation segmented-mirror optical telescopes through enabling rapid design iterations and allowing a more thorough exploration of the design space. A realistic performance assessment requires parametric descriptions of the wind, the structural dynamics, active control of the structure, and the optical response. The current model and its assumptions are presented, with the primary emphasis being on the parameterization of the wind forces. Understanding the temporal spectrum and spatial distribution of wind disturbances inside the telescope enclosure is one of the most challenging aspects in developing the overall parametric model. This involves integrating information from wind tunnel tests, computational fluid dynamics, and measurements at existing observatories. The potential and limitations of control to mitigate the response are also discussed, with realistic constraints on the control bandwidth obtained from the detailed structural model of a particular point design. Finally, initial results are presented on performance trends with a few key parameter variations.

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“…Padin and Davison [11] added both structural dynamic amplification and the response of M1 due to loads on the top end structure. Neither of these latter effects should be significant for a well-designed structure, although their analysis was essential to ensuring that this is true for future telescopes.…”

Section: Introductionmentioning

confidence: 99%

Wind buffeting of large telescopes

MacMynowski

Andersen

2010

Appl. Opt.

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Unsteady wind loads due to turbulence within the telescope enclosure are one of the largest dynamic disturbances for ground-based optical telescopes. The desire to minimize the response to the wind influences the design of the telescope enclosure, structure, and control systems. There is now significant experience in detailed integrated modeling to predict image jitter due to wind. Based on this experience, a relatively simple model is proposed that is verified (from a more detailed model) to capture the relevant physics. In addition to illustrating the important elements of the telescope design that influence wind response, this model is used to understand the sensitivity of telescope image jitter to a wide range of design parameters.

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Model of image degradation due to wind buffeting on an extremely large telescope

Cited by 13 publications

References 4 publications

Wind loads on ground-based telescopes

Wind loads on ground-based telescopes

Parametric modeling and control of telescope wind-induced vibration

Wind buffeting of large telescopes

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