Vortex excitation of rectangular cylinders with a long side normal to the flow
Vortex excitation of rectangular cylinders with a long side normal to the flow
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DOI：
10.1017/s0022112087001770
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发表时间：
1987-07
影响因子：
3.7
通讯作者：
Y. Nakamura;T. Matsukawa
中科院分区：
文献类型：
--
作者：
Y. Nakamura;T. Matsukawa
本文在风洞中用自由振荡和强迫振荡的方法，对边长比为0.2，0.4和0.6，长边垂直于流动的矩形柱体在横向平移模态下的涡激进行了实验研究。研究的折合风速范围（3-12）包括涡共振区。强迫振荡实验包括测量振幅高达长边长度10%的波动升力。实验还进行了一个长的固定分流板的气缸。实验结果表明，矩形柱体的涡激强度与柱体的边长比密切相关。研究结果表明，矩形柱在增大侧边比时，其平均底部压力的临界变化与涡激特性密切相关。根据实验结果，提出了涡激作为流体耦合系统气动弹性颤振的概念。涡激耦合颤振的最本质特征是流体子系统可以被物体运动设置为共振。通过涡共振产生的升力中的快速相位角变化产生了大的异相力分量，该分量激发了主体子系统的运动。
The vortex excitation of rectangular cylinders having side ratios of 0.2, 0.4 and 0.6, with a long side normal to the flow, in a mode of lateral translation, is investigated experimentally in a wind tunnel using free- and forced-oscillation methods. The range of reduced wind speeds investigated, 3-12, includes the vortex-resonance regime. The forced-oscillation experiment includes measurements of the fluctuating lift force at amplitudes up to 10% of the length of a long side. The experiments were also performed on cylinders with a long fixed splitter plate. The results of the measurements show that vortex excitation of a rectangular cylinder is strongly dependent on the side ratio. It is suggested that the critical change of the mean base pressure of an oscillating rectangular cylinder with increasing side ratio is closely correlated with the vortex-excitation characteristics. The concept of vortex excitation as aeroelastic flutter occurring in a fluid-body coupled system is proposed on the basis of the experimental results. The most essential feature of vortex excitation as a coupled flutter is that the fluid subsystem can be set into resonance by the body motion. A rapid phase-angle change in the lift force through vortex resonance produces a large out-of-phase force component which excites the motion of the body subsystem.