考虑表面粗糙度和坡地地形影响的下击暴流壁面射流段风场特性研究

大量的事故和研究表明下击暴流对输电塔线体系有较大的破坏性，但现阶段的研究水平以及部分国外设计规范并不能满足相关的要求。鉴于当前缺乏关于地表粗糙度及坡地地形对下击暴流出流段风场边界层作用机理的深入认识，项目在传统边界层风洞中加装壁面射流装置，通过设置数控阀门对壁面射流流场进行主动控制，从而实现对下击暴流出流段稳态以及非稳态风场的大尺度风洞试验。选取规范中的几种常见地貌表面粗糙度以及坡地参数，采用风洞试验以及数值模拟方法，结合流体力学边界层理论分析，重点研究不同表面粗糙度对壁面射流的边界层的作用机制，揭示粗糙表面的阻力规律与壁面速度律的关系，提出不同粗糙表面地貌时下击暴流风荷载模型，揭示坡地地形对非稳态下击暴流风场的影响规律，得到坡地地形时的修正方法。预期成果可以加深对不同粗糙地貌下击暴流出流段边界层特性及坡地地形工程风荷载的认识，为下击暴流多发地区输电塔线体系的抗风设计提供理论支撑。

A large number of accidents and studies have shown that downburst has a great destructive effect on the transmission line structures, but the research level of the present stage and the related design codes cannot meet the relevant requirements. In consideration of a lack of deeply understanding the surface roughness and escarpment on the mechanism of the wind field boundary layer of the downburst outflow, a wall jet device has been added in the traditional boundary layer wind tunnel. By setting numerical control valve to control the flow field of wall jet actively, the large-scale wind tunnel experiment of stationary and non-stationary downburst outflow is realized. The surface roughness of several common landforms and escarpment parameters in the codes are selected. Using the wind tunnel test and numerical simulation method, combined with the boundary layer theory, the mechanism of different surface roughness on the boundary layer of wall jet will be studied to reveal the relationship between the resistance law of rough surface and the velocity law of wall. The wind loading model of downburst with different rough surface landforms will be proposed. The influence of escarpment on the wind field of downburst outflow will be revealed to obtain the correction method for escarpment terrain. The expected results will deepen the understanding of the characteristics of boundary layer of the downburst outflow and the wind loading of escarpment terrain under different rough landforms, and then provide guidance for the design of transmission line structures.