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Experiments on a square-section cylinder fixed and forced to oscillate transversely in a uniform stream were conducted in
a water tank. The Reynolds number of the experiments is in the range of 3·103 to 104, the amplitude to side length ratioA/D is up to 0.7 and the range of reduced velocity is 4.5<V
r
<12. This study aims at investigating the lock-in phenomenon, the fluctuating lift and the phase shift between fluctuating
lift and displacement of the oscillating cylinder. The problems on the aeroelastic instability relating to present experimental
results have been discussed. The flow visualization clearly shows that there are drastic changes of vortex-shedding from cylinder
at the resonance point and the upper end of the lock-in range. The results of the flow visualization give better understanding
of the physical mechanism of the phase shift.
Project supported by National Natural Science Foundation of China 相似文献
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The water flow over a semicircular weir is investigated numerically and experimentally in this paper. The numerical model
solves the Reynolds equation for a mean flow field with thek-ε-turbulent model. To trace the motion of the free surface, the COF method with geometric reconstruction is employed. The
velocity of the flow is measured by means of LDV technique. Four types of flow patterns, the position of the separation and
reattachment point, the distribution of shear stress on the bed at downstream of the weir are presented and discussed. The
numerical results agree well with the experiment data. 相似文献
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圆柱绕流局部冲刷机制的实验研究 总被引:1,自引:0,他引:1
采用粒子图像测速技术和粒子图像识别技术研究了冲刷坑的演化过程及局部冲刷的流体动力机制。首先研究了动床条件下圆柱周围的床面演化过程,给出垂直对称面输沙率随时间变化以及圆柱下游垂直对称面的沙颗粒浓度和泥沙分布规律;其次针对典型冲刷坑形状固定底床,测量了圆柱下游的瞬时流场,并给出平均流场。结果表明尾流区平均剪应力较低,但垂向涡量和湍流强度较高。分析指出平均剪应力较低的尾流区域,局部冲刷的主要动力机制是尾涡和湍流的综合作用。 相似文献
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