运动雷暴冲击风水平风速时程分析及现象模型

Time Histories of Horizontal Wind Velocity of Moving Thunderstorms and Pheno menological Model

摘要:

运动雷暴冲击风属于一种非稳态风场.为了研究冲击风射流速度、运动速度、射流高度、射流倾角对该流场的影响，使用壁面射流试验装置进行了运动冲击风流场试验.经过分析提出了相应的现象模型，该模型可被用于获得在不同的冲击风参数下的风速时程.最后，选择多个文献给出的不同冲击风水平风速横廓线模型，并结合矢量合成方法获得水平风速时程，并与该现象模型结果对比.结果表明，对于冲击风到达前的风速时程，现象模型与除了与Holmes和Oliver所提出模型有所区别外，与其他模型均较为吻合；而对于冲击风经过后的风速时程，该现象模型能更好地描述实际试验情况.

Abstract:

A moving thunderstorm downburst is a sort of non stationary flow field. In order to study the effects of inlet velocity, translational velocity of a storm, jet height, and the angle of downburst flow with the ground to the field, an experiment was conducted by an impinging jet device. A phenomenon model was proposed based on the experimental results. Under different parameters of downburst, this model is capable of obtaining various time histories of horizontal wind velocity. Finally, according to the different wind speed profiles, time histories of horizontal wind speed produced by combining vector summation method, were compared with those by phenomenological model. In the duration before the arrival of the downbursts, the comparison states a good agreement between them except the Holmes & Oliver model, whereas it is found that the phenomenological model proposed herein has a stronger capacity of characterizing the variation of horizontal wind velocity in the duration of the departure of the downbursts.