Abstract The stability behavior of a simply-supported tube subjected to narrow annular flow in a finite-length gap support at the mid-length of the tube is experimentally investigated. For the experiments, a simply-supported tube and several finite-length gap supports were made considering different gap sizes. Several diffuser angles at the downstream of the support were also tested, since it is believed that the pressure recovery at the exit of the support is much more important than pressure loss at the entrance of the support. In this study, we observed that the tube lost its stability by flutter, and that the critical flow velocity at which the tube lost stability was dependent on the annular gap size and the diffuser angle. Interestingly, the tube with the diffuser angle of 10° lost stability at a lower flow velocity than with the diffuser angle of 20°, for relatively narrow gaps that are in the range of 0.018 to 0.042 gap-to-tube diameter. Differently, for the largest gap of 0.138 gap-to-tube diameter, the diffuser angle of 20° resulted in a lower instability flow velocity. We concluded that there may be different instability mechanisms depending on diffuser angle and related to the narrowness of the gap.

中文翻译：

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有限长度窄间隙支撑中简支管的环流引起的振动

摘要 通过实验研究了简支管在管中段有限长间隙支撑下承受窄环流的稳定性行为。对于实验，考虑到不同的间隙尺寸，制作了一个简支管和几个有限长度的间隙支撑。还测试了支撑件下游的几个扩散角，因为据信支撑件出口处的压力恢复比支撑件入口处的压力损失重要得多。在这项研究中，我们观察到管由于颤振而失去稳定性，并且管失去稳定性的临界流速取决于环形间隙尺寸和扩散器角度。有趣的是，对于在 0.018 到 0.042 间隙到管直径范围内的相对较窄的间隙，扩散器角度为 10° 的管在比扩散器角度为 20° 的情况下在更低的流速下失去稳定性。不同的是，对于 0.138 间隙到管直径的最大间隙，20° 的扩散器角度导致较低的不稳定流速。我们得出结论，根据扩散器角度和间隙的狭窄程度，可能存在不同的不稳定机制。