Abstract The effect of geometry on the transverse galloping instability of rectangular cylinders was studied experimentally for Reynolds numbers between 1,000 and 10,000. In particular, a comparison was made between a rectangular cylinder with rounded corners and a smooth surface, and the same baseline geometry with added surface topology synthesized from two-dimensional Fourier-modes. The effects of the topology amplitude and wavelength were investigated. From measurements of the normal (galloping direction) force coefficient variation with angle-of-attack, it was found that the added surface topology generally had a destabilizing effect relative to the smooth cylinder. At the lowest Reynolds number, the smooth cylinder was stable, while the cylinders with added topology were unstable with respect to galloping. For Reynolds numbers from 5,000 to 10,000, the added topology did not cause a similar instability. However, there was a monotonic increase in the slope of the normal force coefficient at zero angle-of-attack with increasing surface height amplitude, thus moving the geometry closer to the instability threshold. This effect diminished as Reynolds number increased. Overall, for the range of parameters investigated herein, whenever the cylinders with topology were unstable to soft or hard galloping, the larger topology exhibited more favorable galloping resistance characteristics than the one with smaller topology. Topology wavelength was found to have no effect on the galloping behavior of the cylinder for Reynolds numbers below 7500, and a moderate increase in the normal force slope at zero angle of attack with decreasing wavelength for larger Reynolds numbers. The latter effect was associated with an increase in the angle of attack at which the cylinder could become unstable to hard galloping.

中文翻译：

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曲面拓扑结构对矩形圆柱飞驰不稳定性的影响

摘要 对于雷诺数在 1,000 和 10,000 之间的几何形状对矩形圆柱横向飞驰不稳定性的影响进行了实验研究。特别是，在具有圆角和光滑表面的矩形圆柱体与具有从二维傅立叶模式合成的附加表面拓扑结构的相同基线几何形状之间进行了比较。研究了拓扑振幅和波长的影响。从法向（驰骋方向）力系数随迎角变化的测量结果可以看出，增加的表面拓扑结构通常会导致相对于光滑圆柱体的不稳定效应。在最低雷诺数下，光滑圆柱体是稳定的，而添加拓扑的圆柱体在飞驰方面不稳定。对于从 5 开始的雷诺数，000 到 10,000，添加的拓扑不会导致类似的不稳定。然而，随着表面高度振幅的增加，零迎角处的法向力系数的斜率单调增加，从而使几何形状更接近不稳定阈值。这种影响随着雷诺数的增加而减弱。总体而言，对于本文研究的参数范围，每当具有拓扑结构的圆柱体对软或硬驰骋不稳定时，较大的拓扑结构比具有较小拓扑结构的圆柱体表现出更有利的驰骋阻力特性。发现拓扑波长对于雷诺数低于 7500 的圆柱体的驰骋行为没有影响，并且在零攻角处的法向力斜率随着较大雷诺数的波长减小而适度增加。