Wind tunnel investigation of heliostat field wind loads and load reduction measures

Abstract

Most prior wind tunnel investigations of heliostats have focused on isolated units. However, in real-world engineering scenarios, heliostats are typically arranged in rows to maximize efficiency, and the aerodynamic properties of multiple heliostats differ substantially from those of an independent or single heliostat. In this study, wind loads in a heliostat field were evaluated using a new type of rectangular heliostat model at multiple locations within the field. On the basis of wind tunnel testing of the heliostat field, a commonly used operating elevation angle of 40° was selected as the most representative elevation angle, and the wind loads of heliostats at different positions in the heliostat field as well as load-mitigation strategies were investigated. The test results showed that the heliostat field could be qualitatively decomposed into two regions, namely an interior region and an edge region, and the worst-case-scenario forces and moments for each heliostat in the interior region were largely identical. On this basis, two wind load reduction measures were considered: optimizing array arrangement at a fixed field density and employing wind fences. The heliostat field exhibited a typical “edge high, internal low” trend in its wind load coefficients. At a given heliostat field density, variation of heliostat structure arrangements had a substantial impact on wind effects. Based on the results, the generalized blockage ratio formula proposed by Peterka et al. was improved, thereby allowing wind load reduction through variations in field arrangement at the same density. In addition, it was found that a wind fence reduces wind loads mainly for edge region heliostats, similarly to adding an upstream heliostat row.