Twin test 4 of TWEET-IE project: Scale effects on the flow in an urban street canyon. PTV data from wind tunnel experiments at NTUA and TU Delft.

The present data refers to a twin test, as part of the TWEET-IE project (TWEET-IE : Twin Wind tunnels for Energy and the EnvironmenT - Innovations and Excellence, HORIZON-WIDERA-2021-ACCESS-03-01 / PR# 101079125), carried out in the wind tunnels of the Technical University of Delft (TU Delft) and the National Technical University of Athens (NTUA), using measurement equipment mainly provided by TU Delft. An investigation of the scale effects on flow in the urban environment is carried out. More specifically, this urban environment is a series of five consecutive street canyons perpendicular to the approaching flow, simulating the urban fabric, since the street canyon geometry is usually considered as a fundamental component of contemporary cities. The examined canyon was the fourth one with respect to the direction of the approaching flow. The effect of vegetation (hedges at the pedestrian level or roof greening) on the flow is also examined throughout this study. In the wind tunnel of the National Technical University of Athens, all the former cases were investigated for two different values of ambient turbulence intensity corresponding to two distinct experimental configurations (i.e. with and without a passive grid). The study at NTUA was performed with a 3D-3C Robotic Particle Tracking Velocimetry (3D-PTV) System and at TU Delft with a 3D-3C Volumetric PTV system. Both systems can be categorised as volumetric methods. Additionally, surface pressure measurements were conducted in both wind tunnels whereas hot-film anemometry was employed in NTUA’s wind tunnel to supplement the PTV-extracted dataset. Apart from insight into the application itself, the twin test results provide an opportunity to analyse the effects of the different wind tunnel (WT) configurations (i.e. closed-loop WT vs. open jet WT) on Reynolds number sensitivity.本数据集对应一项双子风洞试验，作为TWEET-IE项目（TWEET-IE：面向能源与环境的双子风洞——创新与卓越，HORIZON-WIDERA-2021-ACCESS-03-01 / 项目编号PR# 101079125）的组成部分，试验分别在代尔夫特理工大学（TU Delft）与雅典国立技术大学（NTUA）的风洞内开展，测量设备主要由代尔夫特理工大学提供。 本研究聚焦城市环境流动的尺度效应问题。具体而言，试验模拟的城市环境为五组连续垂直于来流的街道峡谷，以此还原城市肌理——街道峡谷几何形态通常被视为当代城市的基础组成单元。本次考察的峡谷为沿来流方向的第四座峡谷。此外，本研究还探讨了植被（行人高度绿篱或屋顶绿化）对流动的影响。在雅典国立技术大学的风洞中，针对两种不同的环境湍流强度工况（即分别对应加装与未加装被动格栅的两种实验配置）开展了前述全部工况的试验。 雅典国立技术大学的试验采用三维三分量机器人粒子跟踪测速（3D-PTV）系统完成，代尔夫特理工大学的试验则采用三维三分量体视粒子跟踪测速（Volumetric PTV）系统完成，两类系统均属于体视测量方法。此外，两座风洞均开展了表面压力测量，而雅典国立技术大学还额外采用热膜风速测量法对粒子跟踪测速获取的数据集进行补充。除试验应用本身的研究价值外，双子风洞试验结果还为分析不同风洞配置（即闭环风洞与开口射流风洞）对雷诺数敏感性的影响提供了契机。