UNSTEADY FLUID FORCES ACTING ON TWO TANDEM CIRCULAR CYLINDERS SUBJECTED TO TWO-PHASE CROSS-FLOW

To understand the excitation and suppression effects of air bubbles on the vibration of two tandem cylinders, experimental investigations were carried out on the characteristics of unsteady fluid force in the lift direction acting on the downstream cylinder having a pitch-to- diameter ratio of 3.0 and subjected to two-phase bubble cross-flow. The average diameter of bubbles is about 3 to 4 mm. Experiments to measure the unsteady fluid force are performed, changing the void fraction at three different reduced velocities (2.15, 4.88, and 7.05) for oscillation amplitudes ranging from 5.0 to 15.0 mm. The downstream cylinder is forced to oscillate sinusoidally at the natural frequency of the upstream cylinder in water. Experiments reveal the following major characteristics of fluid force: 1) at low reduced velocity, almost no difference is observed in the characteristics with respect to void fraction and oscillation amplitude; 2) air bubbles reduce the fluid force in the range of the void fraction 5% and at a small oscillation amplitude for the lock-in state reduced velocity; and 30 at high reduced velocity, unsteady fluid force increases with void fraction.

• Supplemental Notes:
  • JSME Intl J, v 38 n 2, June 1995, p 219 [8 p, 8 ref, 2 tab, 11 fig]
• Authors:
  • Iijima, T
  • Hara, F
  • Nishikubo, K
• Publication Date: 1995

Language

• English

Subject/Index Terms

• TRT Terms: Cylindrical bodies; Flow; Multiphase flow; Vibration
• Old TRIS Terms: Crossflow; Flow induced vibration; Tandem arrangement
• Subject Areas: Marine Transportation; Materials;

Filing Info

• Accession Number: 00717291
• Record Type: Publication
• Source Agency: British Maritime Technology
• Files: TRIS
• Created Date: Mar 4 1996 12:00AM