Automated terrain generation for precise atmospheric boundary layer simulation in the wind tunnel
Automated terrain generation for precise atmospheric boundary layer simulation in the wind tunnel
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DOI：
10.1016/j.jweia.2020.104276
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发表时间：
2020-12-01
影响因子：
4.8
通讯作者：
Matyas, C. J.
中科院分区：
文献类型：
--
作者：
Catarelli, R. A.;Fernandez-Caban, P. L.;Matyas, C. J.
本文提出了一个两阶段的框架来描述部分大气边界层（ABL）模拟中在网格粗糙度上自然形成的边界层风洞（BLWT）接近流。第一阶段将曲线拟合技术应用于一系列全面的高分辨率空间平均速度剖面测量，以估计大范围均匀（即等高度）粗糙度元件配置的气动粗糙度参数（ARPs）。在这项研究中，使用一种名为Terraformer的自动化（即计算机控制的）62 x 18粗糙度元素阵列来生成33个独特的粗糙度元素场。平均流动结构被捕获到地形变形器的顺风处，其中关键的arps -即。计算了城市冠层衰减系数、零面位移高度、剪切（摩擦）速度、粗糙度长度和Coles尾迹强度系数。与以往的ABL建模方法主要侧重于惯性子层（ISL）的曲线拟合不同，该方法采用粗糙度子层（RSL）内的城市冠层指数廓线、ISL中的对数规律和外尾流层中的尾迹规律来模拟全深度（即从地板到自由流）粗壁湍流边界层。此外，该方法明确捕获了ISL中雷诺兹剪切应力和外层尾迹强度的潜在变异性，从而概括了传统隧道设计产生的自然发展的BLs的特征。第二阶段对每个arp应用形态测量模型，并根据第一阶段的估计进行校准，以预测各种粗糙度元件配置的流动特性，目标是为选择元件配置提供确定性解决方案，以满足用户指定的进近流气动目标。校正后的模型可以有效地在估计之间进行插值，例如，开放地形和郊区地形的arp估计可以应用于第二阶段的模型校准，以预测“粗糙开放”条件下的arp，而无需进一步的实验。本研究的结果表明，将所提出的框架与机械化粗糙度单元网格相结合，可以显著减少BLWT调试所需的试错次数，同时提高流动表征的质量。
This study presents a two-stage framework to characterize boundary layer wind tunnel (BLWT) approach flows naturally developed over grid roughness for partial atmospheric boundary layer (ABL) simulation. The first stage applies curve fitting techniques to a comprehensive series of high-resolution spatially-averaged velocity profile measurements to estimate aerodynamic roughness parameters (ARPs) for a wide range of homogeneous (i.e., equal height) roughness element configurations. For this study, an automated (i.e., computer-controlled) 62 x 18 roughness element array called the Terraformer was used to generate 33 unique roughness element fields. The mean flow structure was captured downwind to the Terraformer, where key ARPs-i.e., the urban canopy attenuation coefficient, zero-plane displacement height, shear (friction) velocity, roughness length, and Coles' wake strength coefficient-were estimated. In contrast to previous ABL modeling methods that primarily focused on curve fitting of the inertial sublayer (ISL), the proposed approach applies the urban canopy exponential profile within the roughness sublayer (RSL), the log law in the ISL, and the law of the wake in the outer wake layer to model full-depth (i.e., floor to freestream) rough-wall turbulent boundary layers. Further, the method explicitly captures potential variability of Reynolds shear stress in the ISL and the wake strength in the outer layer to generalize characterization of naturally-developed BLs produced by traditional tunnel designs. The second stage applies a morphometric model for each ARP-calibrated with estimates from Stage 1-to predict flow characteristics for a wide range of roughness element configurations, with the goal of producing a deterministic solution for selecting an element configuration to satisfy user-specified aerodynamic objectives for the approach flow. The calibrated models effectively interpolate between estimates, e.g., ARPs estimated for open and suburban terrains can be applied in the second stage model calibration to predict ARPs for a "rough-open" condition without further experimentation. The findings of this study demonstrate that coupling the proposed framework with a mechanized roughness element grid can significantly reduce the trial-and-error required to commission a BLWT, while improving the quality of flow characterization.