Flow characteristics around extremely low fineness-ratio circular cylinders
Flow characteristics around extremely low fineness-ratio circular cylinders
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极低细度比圆柱周围的流动特性
DOI：
10.1103/physrevfluids.6.054704
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发表时间：
2021
影响因子：
2.7
通讯作者：
Shigeru Obayashi
中科院分区：
文献类型：
--
作者：
Masahide Kuwata;Yoshiaki Abe;Sho Yokota;Taku Nonomura;Hideo Sawada;Aiko Yakeno;Keisuke Asai;Shigeru Obayashi
在风洞实验中，由于尾流与机械模型支撑之间存在干扰，精确测量海崖体绕流和气动特性一直是一项具有挑战性的任务。本研究的重点是一个自由流对齐的圆柱体具有极低的细度比（轴向长度与直径的比率）范围从0.30到0.50，这从来没有被调查没有干扰的机械模型支持。采用磁悬浮平衡系统消除了模型支架的干扰，测量了雷诺数为~时的阻力场和速度场。当长细比小于1.50时，回流气泡的尺寸增大，气泡内中心轴上的速度分布逐渐向圆盘方向收敛。在雷诺数为的条件下进行了大涡模拟，其阻力系数与实验结果吻合较好。在此基础上，发现阻力系数单调收敛于圆盘的阻力系数，且无局部极大值。这项研究表明，在低长细比制度（0.10-0.50），一个临界的几何形状，在该阻力系数显示局部最大值，不存在于圆柱。随后，进行非定常流分析，其中两个特征频率，即，从阻力系数和俯仰力矩系数的功率谱密度中识别出0.155和0.155。然后通过相位平均法提取了相关的流动结构，其中的相位平均流表示回流泡抽吸，而相位平均流表示回流泡内部的非轴对称结构。
The accurate measurement of flows and aerodynamic characteristics around a bluff body has been a challenging task due to the existence of interference between the wake and mechanical model supports in wind-tunnel experiments. The present study focuses on a freestream-aligned circular cylinder with an extremely low fineness ratio (the ratio of the axial length to diameter) ranging from 0.30 to 0.50, which has never been investigated without interference from a mechanical model support. We employed a magnetic suspension and balance system to eliminate interference from the model support and measured the drag and velocity fields in the diameter-based Reynolds number betweenand. As the fineness ratio decreases below 1.50, the size of the recirculation bubble increases and the velocity distribution on the central axis inside the bubble gradually converges to that of the circular disk. Furthermore, large-eddy simulations were performed in the Reynolds number of, whose drag coefficient agrees well with experiments. Based on those results, it was found that the drag coefficient monotonically converges to that of the circular disk without local maximum. This study revealed that in the low-fineness-ratio regime (0.10–0.50), a critical geometry, at which the drag coefficient shows a local maximum, does not exist in the circular cylinder. Subsequently, unsteady flow analyses were performed, where two characteristic frequencies, i.e.,and 0.155, were identified from power spectral densities of the drag coefficient and the pitching moment coefficient. The associated flow structures are then extracted by a phase-averaging procedure, where the phase-averaged flows withrepresent the recirculation bubble pumping while the phase-averaged flows withshow nonaxisymmetric structures inside the recirculation bubble.
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影响因子：
3.7
作者：
H. Higuchi;H. Sawada;H. Kato
通讯作者：
H. Higuchi;H. Sawada;H. Kato
磁悬浮与平衡系统同步同步测量分析临界几何轴向圆柱周围非定常流动
影响因子：
2.4
作者：
Yokota Sho;Ochiai Taku;Ozawa Yuta;Nonomura Taku;Asai Keisuke
通讯作者：
Asai Keisuke
使用磁悬浮和平衡系统测量的 0.75-2.0 细度比对自由流排列圆柱体气动阻力的影响
影响因子：
2.4
作者：
T. Nonomura;Kei Sato;Keita Fukata;Hayato Nagaike;Hiroyuki Okuizumi;Y. Konishi;K. Asai;H. Sawada
通讯作者：
H. Sawada
长细比为 1.27 至 1.79 的平行于气流的气缸的阻力和背压
DOI：
10.5359/jwe.32.113
发表时间：
2007
期刊：
--
影响因子：
--
作者：
秀夫 澤田;徹也 国益;信一 須田;徹 御簾納;博之 樋口
通讯作者：
博之 樋口
湍流对锐边物体阻力的影响
DOI：
--
发表时间：
1972
期刊：
--
影响因子：
--
作者：
J. Roberson;Chi Lin;Scott G. Rutherford;M. Stine
通讯作者：
M. Stine