Sting-free measurements on a magnetically supported right circular cylinder aligned with the free stream
Sting-free measurements on a magnetically supported right circular cylinder aligned with the free stream
复制标题
DOI：
10.1017/s0022112007008956
复制
发表时间：
2008-01
影响因子：
3.7
通讯作者：
H. Higuchi;H. Sawada;H. Kato
中科院分区：
文献类型：
--
作者：
H. Higuchi;H. Sawada;H. Kato
使用磁悬浮和平衡系统检查了与自由流对齐的不同细度比（长度与直径）的圆柱体上的流动，以避免模型支撑干扰。在较宽的长细比范围内，得到了直圆柱的阻力系数变化规律。粒子图像测速仪（PIV）被用来检查流场，特别是前缘分离剪切层的行为及其对尾流的影响。基于圆柱直径的雷诺数范围为5×104至1.1×105，而实验的主要部分在ReD=1.0×105时进行。对于中等大的细长比，剪切层重新附着与随后的边界层的增长，而在较短的圆柱体，剪切层保持分离。尾流回流区和即时唤醒模式的差异澄清的平均速度和湍流场，包括纵向涡结构的横流平面的唤醒。最小阻力对应于分离的剪切层在圆柱体后缘重新附着的细度比。用遥测技术获得基础压力。压力场和气动力脉动也进行了讨论。
The flow over cylinders of varying fineness ratio (length to diameter) aligned with the free stream was examined using a magnetic suspension and balance system in order to avoid model support interference. The drag coefficient variation of a right circular cylinder was obtained for a wide range of fineness ratios. Particle image velocimetry (PIV) was used to examine the flow field, particularly the behaviour of the leading-edge separation shear layer and its effect on the wake. Reynolds numbers based on the cylinder diameter ranged from 5×104 to 1.1×105, while the major portion of the experiment was conducted at ReD=1.0×105. For moderately large fineness ratio, the shear layer reattaches with subsequent growth of the boundary layer, whereas over shorter cylinders, the shear layer remains detached. Differences in the wake recirculation region and the immediate wake patterns are clarified in terms of both the mean velocity and turbulent flow fields, including longitudinal vortical structures in the cross-flow plane of the wake. The minimum drag corresponded to the fineness ratio for which the separated shear layer reattached at the trailing edge of the cylinder. The base pressure was obtained with a telemetry technique. Pressure fields and aerodynamic force fluctuations are also discussed.