Reducing the drag on a circular cylinder by upstream installation of a small control rod
Reducing the drag on a circular cylinder by upstream installation of a small control rod
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DOI：
10.1016/j.fluiddyn.2004.01.001
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发表时间：
2004-04
影响因子：
1.5
通讯作者：
Sang-joon Lee;Sang-Ik Lee;C. Park
中科院分区：
文献类型：
--
作者：
Sang-joon Lee;Sang-Ik Lee;C. Park
实验研究了在圆柱上游安装小控制棒对圆柱绕流的阻力特性和尾流结构的影响。基于主圆柱直径（D= 30 mm）的雷诺数约为Re= 20 000。对直径d在d/D= 0.133 ~ 0.267范围内的控制棒进行了试验。尾流速度和表面压力分布的测量与变化的间距L（即，中心到中心的距离）之间的主圆柱和控制棒。形状阻力系数是通过对圆柱表面的表面压力进行积分得到的。涡从控制圆柱开始脱落的临界俯仰距离Lc满足关系式Lc/D= 1.5+ 0.083d。在临界俯仰距离处，诸如压力和拖曳力的特征流量基本上改变。当直径d= 7 mm（d/D= 0.233）的控制棒以接近临界值Lc/D= 2.081的节距比安装时，主圆柱的阻力系数减小约29%。然而，在螺距比L/D= 1.833，控制棒直径d/D= 0.233时，观察到包括控制棒在内的总系统阻力的最大减小（约25%）。
The effects of installing a small control rod upstream of a circular cylinder are investigated experimentally, with a focus on the drag characteristics and the wake structure behind the cylinder. The Reynolds number based on the main cylinder diameter (D= 30 mm) is about Re= 20 000. Control rods with diameters d ranging from d/D= 0.133 to 0.267 are tested. Wake velocity and surface-pressure distributions are measured with varying the pitch distance L (ie, center-to-center distance) between the main circular cylinder and the control rod. The form drag coefficient is obtained by integrating the surface pressure on the cylinder surface. The critical pitch distance L c at which vortices start to shed from the control cylinder is found to obey the relation L c/D= 1.5+ 0.083d. Characteristic flow quantities such as pressure and drag force change substantially at the critical pitch distance. The drag coefficient of the main circular cylinder decreases about 29% when a control rod of diameter d= 7 mm (d/D= 0.233) is installed at a pitch ratio close to the critical value of L c/D= 2.081. However, the maximum reduction of the total system drag including that of the control rod (about 25%) is observed at a pitch ratio of L/D= 1.833 with a control rod diameter of d/D= 0.233.