定日镜结构风振响应的时域分析

Heliostat is the key part of Solar Tower power station. It's apt to gust because of its light structure, so the effect of wind load should be taken into account in design. The structure of heliostat is unusual and it often works under several situations, and specialized researches are needed on its response to wind load. Experimenting on rigid model of heliostat using technique of 3-dimensional wind load in wind tunnel, data of surface fluctuating wind pressure's time intervals under 130 phases among which elevation angle varied from 0° to 90° (with step of 10°) and wind direction angle varied from 0° to 180° (with step of 15°) were obtained. A finite element model was constructed to perform mode analysis on heliostat and wind-induced dynamic response calculation, the wind-induced displacement's peak values are given, and moreover, the further research on structure dynamic response law from aspect of cause of the mirror's surface fluctuating wind pressure is developed. The result reveals: when elevation angle is small, background responsive values of mirror's different parts are approximately the same as the multi-phased resonant response occurring at the bottom; as the angle θ increases, airflow separates at the near side and reunite at the other, as forms vortex which enhances dynamic response at the upper part. The paper also analyses some representative phases on their nodes' displacements' response spectrums, compiling heliostat's surface wind pressure wind vibration factors under different phases, as provides groundings for structure design.