Journal of the Korean Solar Energy Society ISSN:1598-6411(Print) 2508-3562(Online) 한국태양에너지학회 논문집

The concentration performance of a heliostat field consisting of hundreds to thousands of reflectors allows for a deformation-based focus deviation of only 3 mrad or less. The most problematic aspect is the wind load; hence, in this study, the extreme wind speed condition was analyzed. Preceding studies such as field experiments, wind tunnel tests, or Reynolds-averaged Navier–Stokes (RANS) simulations were limited to a single heliostat or a single row, such that the characteristics of vortex shedding from the heliostat field could not be practically understood. In this study, the wind flow over the heliostat field in northern Daegu for Concentrating Solar Power (CSP), consisting of 450 reflectors, was analyzed using large eddy simulations with 33 million cells, in order to identify the characteristics of vortex shedding. In the heliostat field, the windward front and the left and right sides received the peak wind load, and the characteristics of vortex shedding were different depending on the position in the field. A fast Fourier transform analysis of the time-series wind pressure confirmed that the vortex shedding frequency ranged from 0.09 to 0.32 s^-1; it was determined that the vortex shedding from the upper and lower sides dominated that of the left and right sides of the heliostat. After predicting the wind load by Large Eddy Simulations (LES), structural analysis was performed to calculate the maximum displacement of the reflector. It was confirmed that the maximum displacement angle of the heliostat at the windward front, which receives the largest wind load at extreme wind events, satisfies the performance requirement of 1 mrad or less.