下击暴流移动增大效应及带协同流壁面射流模拟方法  

A study of translational incremental effect of downburst and wall jet method with co-flow

作　　者：钟永力 晏致涛[1,2] 汪之松 方智远[1] ZHONG Yongli;YAN Zhitao;WANG Zhisong;FANG Zhiyuan(School of Civil Engineering,Chongqing University,Chongqing 400045,China;School of Civil Engineering and Architecture,Chongqing University of Science and Technology,Chongqing 401331,China)

机构地区：[1]重庆大学土木工程学院,重庆400045 [2]重庆科技学院建筑工程学院,重庆401331

出　　处：《建筑结构学报》2021年第4期15-24,共10页Journal of Building Structures

基　　金：国家自然科学基金项目(51478069);重庆市科委项目(CSTC2017JCYJB0210)。

摘　　要：目前对移动型下击暴流的研究主要基于冲击射流模型,但研究中通常考虑的平移速度较低且缩尺比较小。为此,通过风洞试验与数值模拟方法,研究移动冲击射流风场中平移速度对出流段平均风场的影响,得到了平移速度对下击暴流出流段最大风速增大效应的经验表达式。同时考虑到采用壁面射流方法能够得到较大尺度的下击暴流出流段风场,但并未考虑下击暴流移动增大效应。因此,改进了壁面射流模型,通过协同流模拟下击暴流雷暴云平动。采用数值模拟方法研究了协同流对壁面射流平均风剖面特征长度以及特征速度的影响,得到了协同流速度对壁面射流最大风速增大效应的经验表达式。结果表明:随着平移速度的增大,冲击射流出流段的最大平均速度的增幅可达13.3%以上,并且最大风速产生的位置更靠近壁面;在壁面射流方法中引入协同流,能够有效地模拟移动增大效应,通过建立协同增大效应与平移增大效应的对应关系,可较为准确地采用壁面射流方法得到下击暴流任意水平移动速度下的最大平均风剖面。The current investigation on moving downburst flow is mainly based on impinging jet model. However, the translation velocity is usually low hence the scale is normally small. The influences of translational velocity on radial velocity of impinging jet wind field were studied experimentally and numerically. The empirical expression of the effect of translational velocity on the maximum wind speed in the downburst outflow was obtained. The current wall jet approach can generate large-scale wind field of downburst outflow, but it does not consider the downburst translation. Hence, the wall jet model was improved to simulate the translation of downburst by co-flow. To this end, the influence of co-flow on the characteristic length and velocity of the average wind profile of a wall jet was numerically investigated. The empirical expression of the effect of co-flow on the maximum wind speed of wall jet was also obtained. The results show that with the increase of translational velocity, the maximum average velocity of the impinging jet outflow increases by more than 13.3%, and the maximum wind velocity is generated closer to the wall. Co-flow is introduced into the wall jet method, which can simulate the influence of translation effectively. Lastly, the relationship between translating velocity of impinging jet and co-flow velocity of plane wall jet can be determined for downburst outflow simulation. This provides a reference to effectively get the maximum mean velocity profile of downburst outflow at arbitrary translation velocity using wall jet method.

关 键 词：下击暴流 冲击射流 壁面射流 计算流体动力学 移动增大效应 

分 类 号：TU312.1[建筑科学—结构工程] TU311.41