Examination of different wall jet and impinging jet concepts to produce large-scale downburst outflow
Examination of different wall jet and impinging jet concepts to produce large-scale downburst outflow
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DOI：
10.3389/fbuil.2022.980617
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发表时间：
2022-09
影响因子：
4.8
通讯作者：
Alvaro Danilo Mejia;A. Elawady;Krishna Sai Vutukuru;Dejiang Chen;A. Chowdhury
中科院分区：
文献类型：
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作者：
Alvaro Danilo Mejia;A. Elawady;Krishna Sai Vutukuru;Dejiang Chen;A. Chowdhury
雷暴下击暴流是建筑物和其他基础设施严重受损的主要原因。NSF-NHERI风墙（WOW）实验设施的设计和开发下击暴流模拟器的倡议是为了通过扩展设施的现有能力来模拟非天气风，从而为多灾害工程研究开辟新的视野。五种不同的下击暴流模拟器设计已经在WOW的1：15小比例复制品中进行了测试，以确定最佳设计。本文测试的设计概念考虑了2-D冲击射流和2-D壁射流模拟方法。基本的设计方法包括通过在气流管理箱的出口处添加外部修改装置，将现有的大气边界层（ABL）风模拟器转换成下击暴流风。五个竞争的下击暴流模拟器之间的流动特性比较，沿着与比较真实的下击暴流和以前的文献研究结果，已经进行。表面粗糙度长度对峰值风速高度影响的研究表明，二维平面壁射流的实施可以实现具有高雷诺数的大规模外流（更高的峰值速度高度），这在减少尺度效应方面是有利的。总的来说，目前的研究工作表明，四个下击暴流模拟方法是适合采用的，但是，只有一个下击暴流模拟器的基础上，在设施建设的可行性建议。所选的下击暴流模拟器由靠近底部的两个板条系统组成，顶部有一个阻塞物。这种配置能够产生一个大的滚动涡流通过测试部分，这将足以在湍流特性的进一步研究和更大规模的测试模型的测试。
Thunderstorm downburst winds are a major cause of severe damage to buildings and other infrastructure. The initiative of the NSF-NHERI Wall of Wind (WOW) Experimental Facility to design and develop a downburst simulator was established to open new horizons for multi-hazard engineering research by extending the current capabilities of the facility to enable the simulation of non-synoptic winds. Five different downburst simulator designs have been tested in the 1:15 small-scale replica of the WOW to identify the optimal design. The design concepts tested herein considered both the 2-D impinging jet and the 2-D wall jet simulation methods. The basic design methodology consists of transforming the available atmospheric boundary layer (ABL) wind simulator into downburst winds by adding an external modification device to the exit of the flow management box. A flow characterization comparison among the five contending downburst simulators, along with comparisons to real downbursts and previous literature findings, has been conducted. The study on the effect of surface roughness length on the height of the peak wind velocity showed that the implementation of a 2-D plane wall jet enables large-scale outflows (higher peak velocity height) with high Reynold numbers, which is advantageous in terms of reducing scaling effects. In general, the current research work showed that four downburst simulation methods were suitable for adoption; however, only one downburst simulator was recommended based on the feasibility of construction in the facility. The chosen downburst simulator consisted of a two louver slat system near the bottom, with a blockage at the top. This configuration enables producing a large rolling vortex passing through the testing section, which would serve adequately in the further study of turbulent flow characterization and testing of larger scale test models.