FLOW-INDUCED MULTIPLE-MODE VIBRATIONS OF GATES WITH SUBMERGED DISCHARGE
✍ Scribed by P. BILLETER; T. STAUBLI
- Publisher
- Elsevier Science
- Year
- 2000
- Tongue
- English
- Weight
- 320 KB
- Volume
- 14
- Category
- Article
- ISSN
- 0889-9746
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✦ Synopsis
An experimental investigation of #ow-induced vibrations of gates with multiple degrees of freedom is presented. An under#own vertical gate plate with submerged discharge was allowed to oscillate both in the cross-#ow (z-) and in the streamwise (x-) direction. The two purposes of the investigation were to further the insight into the hydrodynamic coupling mechanisms of the two vibration modes and to determine the interaction of the unsteady lift and drag forces. Self-excited vibration tests were run with reduced velocities < PX and < PV from 0)8 to 14, covering a range in which the instability-induced excitation (IIE) due to impinging-leading-edge vortices (ILEV) as well as the transition to galloping (MIE) occurred. The ratio of the natural frequencies of the two vibration modes f V /f X , the gate opening ratio s/d, and the submergence of the gate plate were varied. Depending on the ranges of reduced velocities and frequency ratios, a complex interaction of two di!erent kinds of instability-induced excitation was detected. Furthermore, it was found that streamwise IIE-excitation and cross-#ow galloping coexist. To assess the relevant #uid dynamic ampli"cation and attenuation mechanisms, simultaneous body response and #ow velocity measurements were carried out.
2000 Academic Press