Wind loads on sparse meshes used in antennae of large telescopes

Sivaramakrishnan, K and Yajnik, KS and Jayaraman, V (1988) Wind loads on sparse meshes used in antennae of large telescopes. Technical Report. National Aeronautical Laboratory, Bangalore, India.

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    Abstract

    Tests were conducted in the NAL 0 .9 m wind tunnel to determine the drag on five sparse, meshes of solidity ratios ranging from 0 .054 to 0 .175 . These meshes are being considered for the antennae of the Giant Meterwave Radio Telescope (GMRT) to be constructed near Pune . The present series of tests were specially designed for low incidence range upto 15 degree to supplement the results obtained earlier for larger incidences (V. Jayaraman, 1987). The apparatus for the experiment was specially designed so that the meshes were held in tension, the support interference was eliminated, and the incidence was controllable . Load cells were used to measure the forces acting on the meshes and the data were acquired using HP 9000/300 computer .The variation of the drag coefficient Cd with incidence e and solidity ratio is described approximately by the cerrelation13; Cd a P 1 + b613; where a and b were found to have values 0 .1 and13; 0 .02 for freestream speeds of 15 and 20 m/sec, that is13; for freestream speeds of 15 and 20 m/sec, that is13; for Reynolds numbers (based on the wire diameter) of 4500 - 6000 .

    Item Type: Proj.Doc/Technical Report (Technical Report)
    Uncontrolled Keywords: Sparse meshers;Drag coefficient;Incidence;Wind loads; Antennae;Telescope
    Subjects: ENGINEERING > Instrumentation and Photography
    ENGINEERING > Fluid Mechanics and Thermodynamics
    Division/Department: Flight Mechanics and Control Division, Flight Mechanics and Control Division, Flight Mechanics and Control Division
    Depositing User: Poornima Narayana
    Date Deposited: 06 Dec 2006
    Last Modified: 24 May 2010 09:45
    URI: http://nal-ir.nal.res.in/id/eprint/2118

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