Characteristics of In-line Flow-Induced Vibration in Case of Two Circular Cylinders

Abstract

  The author used an experimental method to clarify characteristics of In-line flow-induced vibration of two circular cylinders. Experiments were conducted on (1) an elastic cylinder and a rigid cylinder; (2) two elastic cylinders by changing their positions in water flows and radiusdistance ratios d/a. When the rigid cylinder was in a downstream position, the range of nondimensional flow velocity that can excite hydrodynamic vibration was widened compared to the case of using a single cylinder. When the rigid cylinder was in an upstream position, the bigger d/a grew, the lower peak amplitude became compared to the single cylinder case. When the rigid cylinder was positioned vertical to flows, it had a wider excitation region than the single cylinder case. When the two elastic cylinders were placed in parallel to flows, the peak amplitudes of the upstream and downstream cylinders were higher than the case (1) with a wider range of nondimensional flow velocity. When the two elastic cylinders were placed perpendicular to flows, the peak amplitude was also higher than the case of using a single rigid cylinder. When they were placed diagonally, the vibration amplitude became smaller after they formed a large angle.