Free v/s forced vibrations of a cylinder at low Re
Free v/s forced vibrations of a cylinder at low Re
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DOI：
10.1080/10618560802055943
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发表时间：
2008-09
影响因子：
1.3
通讯作者：
T. Prasanth;Sanjay Mittal
中科院分区：
文献类型：
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作者：
T. Prasanth;Sanjay Mittal
研究了低雷诺数下低无量纲质量圆柱的自由振动。对5%堵塞进行计算。锁定观察到的范围内的Re，并伴随着滞后在较低以及较高的Re端的同步/锁定区域。众所周知，自由振动的锁定状态取决于振子的无量纲质量。本文计算的结果与Koopmann（Journal of Fluid Mechanics，28，501 - 512，1967）的受迫振动数据在Y max/D与f * 的关系图上进行了比较，其中Y max是最大振幅，f * 是圆柱振动频率与静止圆柱的旋涡脱落频率之比。良好的协议被观察到的临界振幅之间的强迫和自由振动的同步开始所需的。自由振动的结果与线性振子模型的预测进行了比较，假设气缸上的力不受振动的影响。研究发现，对于低质量振子，由于圆柱振荡的涡脱落频率和升力系数的修改导致的锁定制度的增强。
Free vibrations of a circular cylinder of low non-dimensional mass are investigated at low Reynolds numbers. Computations are carried out for 5% blockage. Lock-in is observed for a range of Re and is accompanied with hysteresis at both lower as well as higher Re ends of the synchronisation/lock-in region. It is well known that the lock-in regime for free vibrations depends on the non-dimensional mass of the oscillator. The results from the present computations are compared with the data for forced vibrations from Koopmann (Journal of Fluid Mechanics, 28, 501–512, 1967) on a Y max/D vs. f* plot, where Y max is the maximum oscillation amplitude and f* is the ratio of cylinder vibration frequency to the vortex shedding frequency for a stationary cylinder. Good agreement is observed for the critical amplitude needed for onset of synchronisation between the forced and free vibrations. The results from the free vibrations are compared to the predictions from the linear oscillator model by assuming that the forces on the cylinder are unaffected as a result of vibrations. It is found that, for low mass oscillators, the modification of vortex shedding frequency and lift coefficient due to cylinder oscillations leads to the enhancement of the lock-in regime.