FLOW-INDUCED VIBRATIONS OF SINGLE AND TANDEM SQUARE COLUMNS
FLOW-INDUCED VIBRATIONS OF SINGLE AND TANDEM SQUARE COLUMNS
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单方柱和串联方柱的流激振动
DOI：
10.1115/omae2015-41695
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发表时间：
2015
期刊：
影响因子：
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通讯作者：
R. Jaiman
中科院分区：
文献类型：
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作者：
G. Zhao;N. R. Pillalamarri;R. C. Mysa;R. Jaiman
本文报道了一组数值实验，以了解保持在串联布置的方柱的流致振动。耦合的力和响应动力学的结果，提出了一个孤立的列和一对正方形列的串联配置，下游列是弹性安装和自由振荡的直线和横向方向。通过与孤立方柱的比较，我们评估了尾流诱导和尖角对下游柱的驰振效应。众所周知，圆柱体只经历涡激运动，而方柱的运动在低Re下是涡激运动，在高Re下是驰振运动。通过基于Petrov-Galerkin的有限元求解器，使用任意拉格朗日-欧拉技术来计算流体网格运动，来进行模拟。孤立柱的计算结果与文献中已有的数值结果吻合较好。方形柱和区域的尺寸被设置为具有5%的总堵塞面积。分析了折算速度对流体力、尾迹轮廓和相位角的影响。这项工作也是一种尝试，以提高我们的理解的起源尾流诱导振动的串联安排的海崖体。在串联布置的情况下，上游涡将下游柱上的驻点移动到较低的抽吸区。因此，与振动隔离柱相比，下游柱观察到更大的升力。下游柱的横向载荷和速度之间的相位差决定了上游尾流与下游柱相互作用的程度。当柱速度与横向压力载荷分量同相时，尾涡与下游柱的相互作用最小。对于更高的折合速度（Ur > 15），下游尾流非常宽且不规则，相位角始终接近180°。
This work reports a set of numerical experiments to understand flow-induced vibrations of the square columns kept in a tandem arrangement. Results on the coupled force and response dynamics are presented for an isolated column and for a pair of square columns in the tandem configuration where downstream column is elastically mounted and free to oscillate in in-line and transverse directions. We assess the combined wake-induced and sharp-corner based galloping effects on the downstream column by comparing with the isolated square column counterpart. It is known that the circular cylinders undergo vortex-induced motion alone whereas motion of a square column is vortex-induced at low Re and galloping at high Re. The simulations are performed by means of a Petrov-Galerkin based finite-element solver using Arbitrary Lagrangian-Eulerian technique to account for the fluid mesh motion. The predicted results of the isolated column agree well with the available numerical results in the literature. The dimensions of the square columns and the domain are set in order to a have total blockage area of 5 %. The effects of reduced velocity on the fluid forces, wake contours, and the phase angles are analyzed. This work is also an attempt to enhance our understanding on the origin of wake-induced vibrations in a tandem arrangement of bluff bodies. In the case of tandem arrangement, upstream vortex shifts the stagnation point on the downstream column to the lower suction region. Thus a larger lift force is observed for the downstream column as compared to a vibrating isolated column. Phase difference between the transverse load and velocity of the downstream column determines the extent of upstream wake interaction with downstream column. When the column velocity is in-phase with the transverse pressure load component, interaction of wake vortex with the downstream column is minimum. For higher reduced velocities (Ur > 15), the wake downstream is very wide and irregular and the phase angle is consistently close to 180°.Copyright © 2015 by ASME