Heliostat wind loads: Effects of the aspect ratio and ground clearance ratio

The impact of heliostat aspect ratio (AR) and ground clearance ratio (GR) on static wind load coefficients has been studied in this article. Wind tunnel experiments were undertaken at Thebarton wind tunnel at the University of Adelaide. A high -frequency load cell was used to measure the forces and moments on heliostat models with five AR ranging from 1 to 2, four different pylon hinge heights (0.1 <= GR <= 1) and elevation angles from 0(degrees) to 90(degrees) at a constant azimuth angle of zero degrees. The results show that increasing AR does not have a significant impact on drag and lift coefficients, but increases hinge moment, and the overturning moment coefficient by up to 55 % compared with a square heliostat. The results also indicate that for an approximately constant GR, increasing AR causes a reduction in drag and overturning moment coefficients, and lift coefficients for AR <= 1.5. The effects of GR show that drag coefficient is approximately constant with GR while the lift coefficient increases slightly. It also indicates that increasing GR causes increased overturning moments coefficient and hinge moment coefficients by up to 40 % and 30 %, respectively. Finally, increasing the hinge height of heliostat result in increase in lift coefficient, overturning moment and hinge moment coefficients.