The effect of the chamfered-corner ratio on the characteristics of the wake behind a square and a 2:1 rectangular section model: PIV measurements and POD analysis

IF 2.8 2区工程技术 Q2 ENGINEERING, MECHANICAL

Experimental Thermal and Fluid Science Pub Date : 2025-03-09 DOI:10.1016/j.expthermflusci.2025.111470

Chin-Chen Chou, Kuan-Zu Lee, Cheng-Yang Chung, Kung-Ming Chung

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引用次数: 0

Abstract

Corner-chamfering influences flow characteristics around a 2-dimensional prism to mitigate wind load and wind-induced responses; the side ratio is also an important parameter. This study determines the effect of a corner chamfer on the wake from a 2-dimensional prism (B/D = 1) and a rectangular cross-sectional model for which B/D = 2, where B is the width and D is the height. The effect of the chamfer ratio (C/D, where C represents the length of the chamfer corner) on the leading edge of a models is determined in terms of flow characteristics. The wake strength and the structural integrity of the model are also affected by the chamfer corner ratio.

Velocity and vortex fields are created using Particle Image Velocimetry (PIV) measurements in a wind tunnel for Re = 1.05 × 10⁴. The results show that the mean and the root-mean-square (RMS) velocity coefficients and the turbulent kinetic energy (TKE) in wake region are affected by the value of C/D. The Strouhal number (St) increases as the value of C/D increases for a model for which B/D = 2. The formation length (L_F) increases for a model for which B/D is 1 if corners are chamfered and L_F decreases for a model for which B/D is 2. Chamfered corners can increase vortex shedding frequency for a model for which B/D is 1 and 2.

The velocity component is the input data for proper orthogonal decomposition (POD). POD mode analysis shows that, for a model for which B/D = 1, the energy of the dominant modes increases with C/D but for a model for which B/D = 2, the energy of the dominant modes decreases as C/D increases. The distribution of temporal coefficients (

a_{1}

and

a_{2}

) for a model for which B/D = 1 that has no chamfered corners resembles a sine wave, which is more stable than the distribution for a model with chamfered corners. As C/D increases, the distribution for a₁ and a₂ for a model for which B/D = 2 gradually become stable, so vortex shedding is symmetrical.

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倒角比对正方形和2:1矩形模型后尾迹特性的影响：PIV测量和POD分析

角倒角影响二维棱镜周围的流动特性，以减轻风荷载和风致响应；边长比也是一个重要的参数。本研究从二维棱镜（B/D = 1）和矩形截面模型（B/D = 2，其中B为宽度，D为高度）确定角倒角对尾迹的影响。倒角比（C/D，其中C表示倒角长度）对模型前缘的影响是根据流动特性来确定的。模型的尾迹强度和结构完整性也受倒角比的影响。在Re = 1.05 × 104的条件下，利用粒子图像测速技术（PIV）在风洞中建立了速度场和涡场。结果表明，平均速度系数和均方根速度系数以及尾迹区湍流动能均受C/D值的影响。对于B/D = 2的模型，Strouhal数（St）随着C/D值的增加而增加。当角的B/D为1时，角的长度增大，当角的B/D为2时，角的长度减小。对于B/D为1和2的模型，倒角可以增加旋涡脱落频率。速度分量是正交分解（POD）的输入数据。POD模态分析表明，当B/D = 1时，优势模态能量随C/D的增加而增加，而当B/D = 2时，优势模态能量随C/D的增加而减少。对于B/D = 1且没有倒角的模型，时间系数（a1和a2）的分布类似于正弦波，这比有倒角的模型的分布更稳定。对于B/D = 2的模型，随着C/D的增加，a1和a2的分布逐渐趋于稳定，因此涡脱落是对称的。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Experimental Thermal and Fluid Science 工程技术-工程：机械

CiteScore

6.70

自引率

3.10%

发文量

159

审稿时长

34 days

期刊介绍： Experimental Thermal and Fluid Science provides a forum for research emphasizing experimental work that enhances fundamental understanding of heat transfer, thermodynamics, and fluid mechanics. In addition to the principal areas of research, the journal covers research results in related fields, including combined heat and mass transfer, flows with phase transition, micro- and nano-scale systems, multiphase flow, combustion, radiative transfer, porous media, cryogenics, turbulence, and novel experimental techniques.