A summary of experimental studies on heliostat wind loads in a turbulent atmospheric boundary layer

The aerodynamic loads on heliostats have been investigated through an extensive range of experimental studies at the University of Adelaide in association with the Australian Solar Thermal Research Institute (ASTRI). Applied modelling techniques using spires and roughness elements were adopted for generation and characterisation of the temporal and spatial turbulence fluctuations, matching those in the lower region of the atmospheric boundary layer (ABL) where full-scale heliostats are positioned. Heliostat wind loads were found to be highly dependent on the critical scaling parameters of the heliostat and the turbulence intensities and scales in the ABL flow. The peak drag and lift coefficients on heliostats followed a similar variation with elevation and azimuth angles to those previously reported in the literature at a similar turbulence intensity. However, the current study revealed a linear increase of the peak drag and lift coefficients on heliostats in operating and stow positions with a parameter defined by the product of the turbulence intensity and the ratio of the turbulence length scales to the heliostat chord length.