下击暴流作用下定日镜表面风压数值模拟研究

为了研究下击暴流作用下塔式太阳能定日镜表面的风压分布特征,文章采用计算流体动力学方法对下击暴流作用下,不同径向位置和不同工作俯仰角的定日镜表面风压进行了数值模拟,并将模拟结果与大气边界层近地风作用下定日镜表面的风压特性进行了比较分析。分析结果表明:当定日镜正常工作时,下击暴流作用下,迎风面风压呈现出中间高两边低的分布趋势,风压峰值位于定日镜中部,背风面风压中间低两边高;随着俯仰角逐渐增大,下击暴流作用下,定日镜迎风面压力峰值中心从定日镜下边缘逐渐上移,最大压力值和高压区范围也逐渐增大,背风面负压值逐渐减小且谷值中心逐渐下移;与常规风相比,下击暴流作用下,定日镜表面风压受径向距离影响明显,当镜面垂直于地面时,定日镜迎风面和背风面表面风压随着定日镜与下击暴流风暴中心之间径向距离的增大而减小;在定日镜抗雷暴下击暴流强风的设计过程中,须要考虑下击暴流和常规风的速度场、气压场的不同,及其所导致的定日镜表面风压分布特征的变化。

Numerical simulation wind pressure of heliostat under downburst

In order to study the wind pressure characteristics of heliostat under downburst,the wind pressure of heliostat with different pitch angles at different radial positions in downburst wind field was numerically simulated by computational fluid dynamics method in this paper,and the simulation results are compared with wind pressure characteristics under the action of normal wind.The results show that,when the heliostat works normally,the wind pressure on the windward side appears to be higher in the middle and lower on both sides under the action of the downburst,and the wind pressure on the leeward side is higher on both sides.With the increasing pitch angles,the peak pressure on the windward side gradually moves up from the lower edge of the heliostat,and the maximum pressure value and the area of the high pressure area also gradually increase,the negative pressure on leeward side gradually decreases and the valley center moves down.Compared with the atmospheric boundary layer wind,the wind pressure on the heliostat is significantly affected by the radial distance under the downburst.When the mirror is perpendicular to the ground,the wind pressure both windward and leeward sides decreases as the radial distance of the storm center increases.As designing of heliostat anti-downburst wind,it is necessary to consider the variation in the characteristics of wind pressure distribution on the heliostat caused by the difference between the velocity field and the pressure field of the downburst and normal wind.