复杂山地风场幅值特性试验研究

复杂山地具有与单个山体完全不同的风场特性,为了研究平均和脉动风速在复杂山地中的空间分布规律,进行了不同山体间隔距离、不同遮挡山体坡度和高度的复杂三维山体模型边界层风洞试验。试验结果表明:随着间隔距离增加,山顶近地平均风速最大加速比迅速减小;背风面山脚加速比迅速由正值减小为负值。随着遮挡山体坡度增大,山顶加速比迅速增大,最后趋于稳定。遮挡山体坡度小于临界坡度时,背风面山脚加速比为负值,反之则为正值。脉动风速均方根加速比随着遮挡距离的增大,逐渐线性向单个山体的结果靠拢;当受扰山体坡度大于遮挡山体坡度时,背风面山脚脉动风加速效应主要由受扰山体控制,反之则由遮挡山体控制。遮挡山体高度对平均风和脉动风速均方根加速比影响都较小。最后根据试验结果提出了复杂山地风场平均及脉动风速均方根计算修正模型。

EXPERIMENTAL RESEARCH ON AMPLITUDE CHARACTERISTICS OF COMPLEX HILLY TERRAIN WIND FIELD

There is a great difference between the wind field characteristics in a complex hilly terrain and that in a single hill.In order to get the distribution of mean and fluctuating wind velocity in a complex hilly terrain,several wind tunnel tests with different interval distances,different slopes and heights have been done.The results indicate that,with the increasing of the interval distance,the mean velocity speed-up ratio at the hilltop reduces quickly and that at the leeward changes from positive to negative quickly.With the increasing of the slope,the mean velocity speed-up ratio at the hilltop increases and then finally keeps stable.There is a critical value of the slope.When the slope is less than the value,the speed-up ratio at the leeward is negative,otherwise it becomes positive.The root mean square speed-up ratio of the fluctuation wind velocity becomes the same as that under the condition of the single hill in the form of the linear model.When the slope of the distributed hill is lager than the obscure hill,the root mean square speed-up ratio mainly depends on the distributed hill,otherwise,it depends on the obscure hill.The effects of the height of the obscure hill are all insignificant.The revised models of the mean velocity and the fluctuation velocity root mean square are proposed according to the wind tunnel test results.