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Dynamic instability of a simply-supported rod subjected to axial-leakage-flow in a finite-length narrow gap support
Heung Seok Kang

Last modified: 2018-04-13


The stability 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 to see if a dynamic instability occurs. For this experiment, a simply-supported tube of 2.5 m length and several finite-length narrow-gap supports have been made considering different gap size and diffuser angles at the downstream of the support. The tube was observed to lose stability by flutter. The critical flow velocity was strongly dependent on the annular gap size and diffuser angle. A perturbation pressure in the finite length gap support and pressure loss at the entrance and exit of the support are the major parameters for the critical flow velocity of the simply-supported tube. Above all thinges, the exit boundary conditiion for pressure recovery is found to be predominant for the dynamic instability. However, flutter instability does not materialize for lossless boundaries such as short-lossless inlet and free-discharge outlet.


cylinder vibration;flow-induced vibration;dynamic instability;flutter;finite-length gap support;gapflow;leakage annular flow

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