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Wind and Structures
  Volume 14, Number 2, March 2011 , pages 167-186
DOI: https://doi.org/10.12989/was.2011.14.2.167
 


Autorotation of square plates, with application to windborne debris
P. Martinez-Vazquez, M. Sterling, C.J. Baker, A.D. Quinn and P.J. Richards

 
Abstract
    This paper presents the results of measurements relating to the aerodynamic forces on flat square plates which were allowed to rotate at different speeds about their horizontal axis, by modifying the velocity of the incoming flow. A 1 m square test-sheet and a 0.3 m square test-sheet were fitted with a number of pressure sensors in order to obtain information relating to the instantaneous pressure distribution acting on the test-sheet; a compact gyroscope to record the angular velocity during the rotational motion was also implemented. Previous work on autorotation has illustrated that the angular velocity varies with respect to the torque induced by the wind, the thickness and aspect ratio of the testsheet,any frictional effects present at the bearings, and the vorticity generated through the interaction between the plate and the wind flow. The current paper sets out a method based on the solution of the equation of motion of a rotating plate which enables the determination of angular velocities on autorotating elements to be predicted. This approach is then used in conjunction with the experimental data in order to evaluate the damping introduced by the frictional effects at the bearings during steady autorotation.
 
Key Words
    autorotation; aerodynamic forces; windborne debris.
 
Address
P. Martinez-Vazquez, M. Sterling, C.J. Baker, A.D. Quinn : School of Civil Engineering, University of Birmingham, UK
P.J. Richards :Department of Mechanical Engineering, University of Auckland, New Zealand
 

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